Category: Vaccine

Prevalence of fear and toxicity in YouTube comments

Our objective was to assess the effects of trolling comments on anti-vaccine videos, specifically examining whether toxicity in comments for a video is associated with the level of fear expressed in the comments for the same video on YouTube. We first analysed the relationship between toxicity and fear at the video level. We employed a machine learning approachGoogles Perspective API and a RoBERTa-based modelto quantify fear and toxicity levels in each comment, and wecomputed their mean for each video (see Methods). Our results demonstrate that highly fearful and highly toxic comments only constitute a portion of all comments. As depicted in Fig.1a, the top 20th percentile comments have fear and toxicity scores of 0.03 and 0.29, respectively, on a 01 scale. These scores illustrate highly skewed distributions, with a narrow dynamic range for fear and a wide dynamic range for toxicity.

We then investigated the temporal dynamics of fear and toxicity within comment sections. Figure1b provides an example of the absence of evident temporal patterns for fear and toxicity, where highly toxic and highly fearful comments appeared sporadically and abruptly. We also analysed the temporal intermittency of such highly toxic and highly fearful comments and found a heavy-tailed distribution for the intervals between highly toxic and highly fearful comments (Fig.1c)30.

One may question whether fear and toxicity are inherently correlated within an individual comment. By analysing the scatter plot of fear and toxicity scores for each comment (Fig.1d), we found that this is not the case. To summarise the findings thus far, both toxicity and fear in comments exhibit burst-like dynamics; however, they do not have a one-to-one correspondence and are not the same signal.

Fear and toxicity in YouTube comments at the comment and video levels. (a) Distribution of fear and toxicity scores for each comment, with the top 20th percentile thresholds indicated by vertical lines. Both distributions exhibit strong skewness, suggesting that many comments possess low values. (b) Time series of fear and toxicity scores for the first 100 comments on a specific video. The horizontal lines correspond to the 20th percentile thresholds from (a), and the data points surpassing these thresholds are marked. (c) A log-log plot of CCDFs indicating the probability of the interval time between all highly fearful and highly toxic comments at the comment level, which indicates that this interval time adheres to a heavy-tailed distribution. (d) Scatterplot of fear and toxicity scores per comment. (e) Distribution of average fear and toxicity scores per video. (f) Scatter plots of average fear and toxicity scores per video. The red line shows a regression line. The Pearson correlation coefficient between toxicity and fear was 0.10 ((p=0.00)), the coefficient of the single regression analysis was 0.06, and the distance correlation was 0.16.

We quantified the distributions of fear and toxicity and their correlation in comments at the video level. Figure1e shows the distribution of average fear and toxicity scores for comments on each video. These distributions differ from those at the comment level (Fig.1a) and more closely resemble a Gaussian distribution. Figure1f shows a scatter plot of fear and toxicity scores, indicating a weak correlation between average fear and toxicity scores at the video level. Based on these findings, we decided to focus on the average fear and toxicity scores compiled across entire or partial comment sections as significant metrics31.

Next, we examined the features associated with fear at the video level. To account for potential covariates, we conducted an ordinary least square (OLS) regression analysis with the videos as data points and the average fear of comments per video as the dependent variable. The independent variables in the regression analysis include the videos base features (e.g., view counts), the videos emotion-related features (e.g., fear score in a title), the videos topics, and the comment features (e.g., fear, toxicity), all detailed in Methods.

Figure2 shows the results of the regression analysis at the video level. Notably, the analysis identified that average toxicity is a significant variable even when controlling for other variables, implying a strong association between toxicity and fear in comments aggregated at the video level. Since the fear and toxicity scores are all on a scale from 0 to 1, the coefficients of the regression indicate how much fear increases when the toxicity score increases from 0 to 1. Alarge and significant cofficient indicates that the variable is correlated with the degree of toxicity in the comment section of the video. Additionally, we found that fear in comments was significantly associated with the topics of viruses and childrens diseases, which aligns with previous research linking these topics to fear among anti-vaccine groups5,32. Furthermore, fear in the title, description, and transcript is positively associated with fear in comments, which supports previous research indicating that the emotional content of videos can be associated with viewers emotions33. By contrast, the analysis revealed the toxicity of video content is only minimally related to fear in comments. The analysis did not reveal any significant relationship between pseudoscience and fear in comments, suggesting that the scientific nature of the content does not significantly affect fear in comments. See Supplementary Information for models with some features ablated.

Results for video-level regression. (a) The coefficient of variables with 95% CIs. The stars indicate the p values of the t-test: *** for (p < 0.001), ** for (p < 0.01), and * for (p < 0.05). The model intercept parameter is not shown.

Lastly, we explored the impact of early toxic comments on subsequent comments, focusing on emotional aspects. Based on previous research that demonstrated a connection between early comment features and later sentiments in comments34, we employed a similar approach. A key factor to consider is the window size of comments, which sets the threshold for determining the number of early comments (Fig.3). We compared various window sizes, with (k={10,20,30,40,50}) to gauge their effects. The objective was to calculate the average toxicity and fear in comments within these window sizes (see Methods), and subsequently incorporate the variable groups 1, 2, and 3 features used in the previous regression analysis to estimate the average fear in comments following the threshold k (Model 4 in Fig.3a).

Considering thatYouTube comments are not necessarily arranged in chronological order, we included not only the recency of comments but also their engagement, specifically the number of likes, which highly affects the order of comments. The number of likes is crucial when assessing the impact of toxic comments because the higher the value, the more likely a comment is to appear at the top of the comment list and, consequently, has a greater likelihood of influencing other comments19,35. In this study, we aimed to account for the effect of highly liked comments. Therefore, we used the average toxicity of comments within window k that have a like count in the top 20th percentile or higher, as the explanatory variable (i.e., the toxicity of highly liked comments, see Methods) (Model 5 in Fig.3a). This approach replaced the use of the average toxicity of comments within window k in Model 4.

Figure3b shows the coefficients for all comments (top) and highly liked comments (bottom) across thewindow sizes (k={10,20,30,40,50}) in the regression analysis. For all comments and after controlling for fear in early comments, the toxicity of early comments is slightly positively related to fear in later comments across all window sizes (k) (but not significant), after controlling for fear in early comments. This result suggests that early toxicity is associated with later fear independently of early fear. Note that early fear is strongly associated with later fear, confirming the contagion of homogeneous emotions. Looking at the toxicity of highly liked comments at the bottom of Fig.3b, we can also see that only the coefficients for the toxicity of highly liked comments are significant (4 out of 5 cases). Moreover, the toxicity of highly liked comments has a particularly large coefficient (about 1.3 times), indicating that the association of the liked comments is stronger than all comments. It should also be noted that in the regression analysis, the other video-related variables were controlled, as described in Factors that elicit fear in YouTube comments, suggesting that emotional contagion was likely to occur between comments.

Measuring the association of toxicity of early comments with the fear in later comments. (a) Illustration of the problem setting. N comments in chronological order for a given video are divided into early and later halves, separated by k. Then, the average fear of comments in the comment range is predicted by the variables noted in Model 4 and Model 5, respectively, and the coefficients are obtained. (b) Forest plots showing the coefficients of average toxicity of comments and highly liked comments across window size (k={10,20,30,40,50}). Both are positive regardless of k, but only the mean toxicity of highly liked comments is largely significant. The average toxicity of highly liked comments has a high coefficient compared to the average toxicity of all comments (1.3 times higher in the average value in the five windows).

One might wonder whether there is the opposite direction of the effect, i.e., is early fear associated with later toxicity in comments? To answer this question, we examined two more modelsmodel 6 and model 7. In both models, we assigned the mean toxicity of later comments as a dependent variable, and in model 7, we modified model 5 by replacing the average toxicity of highly liked early comments with the mean fear of highly liked early comments in the independent variable (Fig.4a). Figure4b suggests that the coefficients for fear in early comments are all positive. Also, the coefficients for fear of highly liked comments are largely significant (4 out of 5 cases). These findings indicate that in the comment section of anti-vaccine YouTube videos, the influence of the toxicity and fear in comments is bidirectional, with the toxicity of early highly liked comments having an influence on the fear in subsequent comments and vice versa.

Measuring the association of the fear of early comments with the toxicity in later comments. (a) Illustration of the problem set. N comments in chronological order for a given video are divided into early and later halves, separated by k. Then, the mean fear in comments in the comment range is inferred by the variables noted in Model 6 and Model 7, respectively, and the coefficients are obtained. (b) Forest plots showing the coefficients of the fear in comments and the fear in highly liked comments, for (k={10,20,30,40,50}). Only the coefficients for fear in highly liked comments are largely significant (3 out of 5 cases).

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The impact of toxic trolling comments on anti-vaccine YouTube videos | Scientific Reports - Nature.com

Busting myths you may have heard about the flu and cold

This season's influenza vaccines have been 42% effective so far, according to a new interim estimate from the Centers for Disease Control and Prevention, amounting to protection against the virus that appears as good or better than seasons going back to 2016.

First previewed Wednesday at a meeting of the CDC's Advisory Committee on Immunization Practices, details of the latest vaccine effectiveness, referred to as VE, estimates werepublished Thursday in the agency's Morbidity and Mortality Weekly Report.

"We're right in the range that we typically see when the vaccine is a good match with the viruses that are circulating. Good VE, and it's working consistent with past years," said Sascha Ellington, head of the CDC's influenza prevention and control team.

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The exact strains selected to be targeted by flu vaccines are tweaked each year based on what health authorities project will be the best match to the circulating viruses each season. In recent years, vaccines have been designed to target four different subtypes of flu: two from the influenza A group of viruses and two from influenza B.

The estimates are from four ongoing studies backed by the agency which put together actively test patients and draw on records from immunization registries, clinics, urgent care services, emergency rooms, hospitals and health insurance claims around the U.S.

Estimates show vaccines this season were between 52% and 61% effective in protecting children against influenza hospitalization. In adults, the shots were estimated to be 41% to 44% effective.

While effectiveness looks good for this season, Ellington warned that declining vaccination rates means the U.S. could still see fewer hospitalizations and deaths prevented by vaccines this season.

"To prevent flu hospitalizations and deaths on the population level, we need both good vaccine effectiveness and we need people to get vaccinated," she said.

Ellington said the agency continues to recommend that people get a flu vaccine if they have not yet this season. The CDC says significant flu activity can last until May.

Some regions of the country have reported renewed increases in flu activity for recent weeks, after a slowdown from a peak during the winter holidays.

Effectiveness looked especially high so far this season for influenza B infections, Ellington said.

This season marked the first since before 2020 with significant amounts of influenza B cases, after the COVID-19 pandemic upended the usual spread of the virus.

Based on data from outpatient settings, like urgent care clinics and emergency rooms, the vaccines were 78% effective in adults and at least 64% in kids for cutting the risk of a visit from influenza B.

"We really have to go back a number of years to look at influenza B effectiveness. And when you go back for those older years, you do see it ranging usually in the 40 to 60 percent range," said Ellington.

Effectiveness estimates for influenza A, which typically makes up the lion's share of cases, looked similar to previous years overall: from 46% to 59% in kids and 27% to 46% in adults for outpatient settings.

Overall, a majority of tests reported so far this season from public health labs have been from a subtype of influenza A known as A(H1N1)pdm09, the descendant of the swine flu virus that drove a flu pandemic in 2009. That is different from last year, when the influenza A(H3N2) virus dominated cases.

Ellington said that experts sometimes see vaccine effectiveness trend higher during seasons dominated by H1N1. But she cautioned that other factors, like changes to the virus and what strains were selected to be in the season's shots, muddy the picture.

"I think the general consensus is that they would expect perhaps a little higher VE when it's an H1N1 season, but that doesn't always come to fruition," she said.

The new estimates come as the Food and Drug Administration is set to vote on the recipe used for next season's influenza vaccines, at a meeting of its Vaccines and Related Biological Products Advisory Committee.

A major change could be in store. FDA and World Health Organization panels have called on flu manufacturers to strip out an obsolete component of the vaccines targeted at the influenza B Yamagata subtype, which disappeared during the COVID-19 pandemic.

That could effectively open up one of the seats in the vaccines, dropping them next season from quadrivalent formulations targeting four different antigens in a single shot to trivalent.

"As a result, it is likely that in the United States, all influenza vaccines in the 20242025 season will be trivalent," wrote committee member Dr. Arnold Monto Wednesday, in an article published by the New England Journal of Medicine co-authored by officials from the FDA and the U.K. Health Security Agency.

Removing influenza B Yamagata could make room for new components in the flu vaccine recipe that might boost effectiveness, though these additions could be years away.

"Replacing the B/Yamagata component with another component or formulation will require further stepwise planning and is more of a long-term goal for improving vaccine effectiveness," they wrote.

Alexander Tin is a digital reporter for CBS News based in the Washington, D.C. bureau. He covers the Biden administration's public health agencies, including the federal response to infectious disease outbreaks like COVID-19.

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CDC finds flu shots 42% effective this season, better than some recent years - CBS News

Jennifer DeCuir, MD, PhD1; Amanda B. Payne, PhD1; Wesley H. Self, MD2; Elizabeth A.K. Rowley, DrPH3; Kristin Dascomb, MD, PhD4; Malini B. DeSilva, MD5; Stephanie A. Irving, MHS6; Shaun J. Grannis, MD7,8; Toan C. Ong, PhD9; Nicola P. Klein, MD, PhD10; Zachary A. Weber, PhD3; Sarah E. Reese, PhD3; Sarah W. Ball, ScD3; Michelle A. Barron9; Allison L. Naleway, PhD6; Brian E. Dixon, PhD7,8; Inih Essien, OD5; Daniel Bride, MS4; Karthik Natarajan, PhD11,12; Bruce Fireman10; Ami B. Shah, MPH1,13; Erica Okwuazi, MSc1,13; Ryan Wiegand, PhD1; Yuwei Zhu, MD2; Adam S. Lauring, MD, PhD14; Emily T. Martin, PhD14; Manjusha Gaglani, MBBS15,16; Ithan D. Peltan, MD17,18; Samuel M. Brown, MD17,18; Adit A. Ginde, MD9; Nicholas M. Mohr, MD19; Kevin W. Gibbs, MD20; David N. Hager, MD, PhD21; Matthew Prekker, MD22; Amira Mohamed, MD23; Vasisht Srinivasan, MD24; Jay S. Steingrub, MD25; Akram Khan, MD26; Laurence W. Busse, MD27; Abhijit Duggal, MD28; Jennifer G. Wilson, MD29; Steven Y. Chang, MD, PhD30; Christopher Mallow, MD31; Jennie H. Kwon, DO32; Matthew C. Exline, MD33; Cristie Columbus, MD15,34; Ivana A. Vaughn, PhD35; Basmah Safdar, MD36; Jarrod M. Mosier, MD37; Estelle S. Harris, MD18; Jonathan D. Casey, MD2; James D. Chappell, MD, PhD2; Carlos G. Grijalva, MD2; Sydney A. Swan2; Cassandra Johnson, MS2; Nathaniel M. Lewis, PhD38; Sascha Ellington, PhD38; Katherine Adams, MPH38; Mark W. Tenforde, MD, PhD38; Clinton R. Paden, PhD1; Fatimah S. Dawood, MD1; Katherine E. Fleming-Dutra, MD1; Diya Surie, MD1; Ruth Link-Gelles, PhD1; CDC COVID-19 Vaccine Effectiveness Collaborators (View author affiliations)

What is already known about this topic?

In September 2023, CDCs Advisory Committee on Immunization Practices recommended updated 20232024 (monovalent XBB.1.5) COVID-19 vaccination for all persons aged 6 months to prevent COVID-19, including severe disease. Few estimates of updated 20232024 vaccine effectiveness against medically attended COVID-19 are available.

What is added by this report?

Receipt of an updated COVID-19 vaccine dose provided increased protection against COVID-19associated emergency department and urgent care encounters and hospitalization compared with no receipt of an updated vaccine dose among immunocompetent U.S. adults during a period of multiple cocirculating SARS-CoV-2 Omicron lineages.

What are the implications for public health practice?

These findings support CDC recommendations for updated 20232024 COVID-19 vaccination. All persons aged 6 months should receive updated 20232024 COVID-19 vaccine.

In September 2023, CDCs Advisory Committee on Immunization Practices recommended updated 20232024 (monovalent XBB.1.5) COVID-19 vaccination for all persons aged 6 months to prevent COVID-19, including severe disease. However, few estimates of updated vaccine effectiveness (VE) against medically attended illness are available. This analysis evaluated VE of an updated COVID-19 vaccine dose against COVID-19associated emergency department (ED) or urgent care (UC) encounters and hospitalization among immunocompetent adults aged 18 years during September 2023January 2024 using a test-negative, case-control design with data from two CDC VE networks. VE against COVID-19associated ED/UC encounters was 51% (95% CI = 47%54%) during the first 759 days after an updated dose and 39% (95% CI = 33%45%) during the 60119 days after an updated dose. VE estimates against COVID-19associated hospitalization from two CDC VE networks were 52% (95% CI = 47%57%) and 43% (95% CI = 27%56%), with a median interval from updated dose of 42 and 47 days, respectively. Updated COVID-19 vaccine provided increased protection against COVID-19associated ED/UC encounters and hospitalization among immunocompetent adults. These results support CDC recommendations for updated 20232024 COVID-19 vaccination. All persons aged 6 months should receive updated 20232024 COVID-19 vaccine.

On September 12, 2023, CDCs Advisory Committee on Immunization Practices recommended updated 20232024 COVID-19 vaccination with a monovalent XBB.1.5derived vaccine for all persons aged 6 months to prevent COVID-19, including severe disease (1). Although 1 updated vaccine dose is recommended for most persons aged 5 years, vaccination coverage with updated vaccines has remained low,* including among those at highest risk for severe disease, such as adults aged 65 years. Thousands of persons in the United States continue to be hospitalized with COVID-19 each week, including approximately 31,000 during January 713, 2024, despite endemicity and increased population immunity to SARS-CoV-2. This analysis estimated updated COVID-19 vaccine effectiveness (VE) during September 2023January 2024 among immunocompetent adults aged 18 years against COVID-19associated emergency department (ED) or urgent care (UC) encounters in one CDC VE network and VE against COVID-19associated hospitalization in two CDC VE networks.

Methods for Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network (VISION) and Investigating Respiratory Viruses in the Acutely Ill (IVY) VE analyses have been described (2,3). VISION is a multisite, electronic health records (EHR)based network including 369 EDs and UCs and 229 hospitals in eight states that uses a test-negative, case-control design to estimate COVID-19 VE. Eligible patients must receive molecular testing (e.g., real-time reverse transcriptionpolymerase chain reaction [RT-PCR] testing) for SARS-CoV-2 during the 10 days preceding or up to 72 hours after a COVID-19associated ED/UC encounter or hospital admission.** COVID-19 vaccination history is ascertained from state or jurisdictional registries, EHRs, and, in a subset of sites, medical claims data.

IVY is a multisite, inpatient network including 26 hospitals in 20 U.S. states that uses a test-negative, case-control design to prospectively enroll patients with COVID-19like illness (CLI) who receive testing for SARS-CoV-2 within 10 days of illness onset and 3 days of hospital admission. Nasal swabs are collected for central RT-PCR testing for SARS-CoV-2 at Vanderbilt University Medical Center (Nashville, Tennessee), and SARS-CoV-2positive specimens are sent to the University of Michigan (Ann Arbor, Michigan) for whole genome sequencing to identify SARS-CoV-2 lineages. Demographic and clinical data are collected through EHR review and patient or proxy interview. COVID-19 vaccination history is ascertained from state or jurisdictional registries, EHRs, and self-report.

The VISION and IVY networks conducted separate VE analyses. In both analyses, immunocompetent adults aged 18 years who 1) had a medical encounter at an ED/UC (VISION only) or 2) were hospitalized (VISION and IVY) at a participating facility with CLI were included. Case-patients were those who received a positive SARS-CoV-2 molecular test result, and control patients were those who received a negative SARS-CoV-2 test result. Participants were excluded if they 1) received a COVID-19 vaccine dose <7 days before their eligible ED/UC encounter or hospitalization; 2) received an updated COVID-19 vaccine dose <2 months after receiving a previous COVID-19 vaccine dose (to align with current Advisory Committee on Immunization Practices recommendations); 3) received a bivalent COVID-19 vaccine dose after September 10, 2023; 4) received an updated COVID-19 vaccine dose before September 13, 2023; or 5) received >1 updated COVID-19 vaccine dose.*** Case-patients were also excluded if they had received a positive influenza or respiratory syncytial virus (RSV) molecular test result at the time of their CLI encounter. Because of potential confounding caused by the association between COVID-19 and influenza vaccination behaviors, control patients who received positive or indeterminant influenza test results were excluded from the primary analysis (4). A sensitivity analysis including these control patients was also conducted.

Odds ratios (ORs) and 95% CIs were estimated using multivariable logistic regression comparing persons who received an updated COVID-19 vaccine dose with those who did not, irrespective of the number of previous original or bivalent COVID-19 vaccine doses received (if any), among case-patients and control patients. VE models were adjusted for age, sex, race and ethnicity, calendar time, and geographic region. VE was calculated as (1 adjusted OR) 100%. In the VISION network, VE was estimated for adults aged 18 years and by age group (1864 and 65 years). In the IVY network, statistical power was limited among younger adults because of lower vaccination coverage and fewer COVID-19associated hospitalizations among persons aged 1864 years; therefore, VE against hospitalization was estimated only for adults aged 18 years and 65 years.

Analyses were conducted using R software (version 4.3.2; R Foundation) for the VISION analysis and SAS software (version 9.4; SAS Institute) for the IVY analysis. This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.**** This activity was reviewed and approved as a research activity by one VISION site.

Among adults aged 18 years in the VISION network, 128,825 ED/UC encounters met inclusion criteria, including 17,229 case-patients and 111,596 control patients (Table 1). A total of 1,297 (8%) case-patients and 13,378 (12%) control patients had received an updated COVID-19 vaccine dose. VE against COVID-19associated ED/UC encounters was 51% (95% CI = 47%54%) in the first 759 days after an updated dose (median interval since updated dose = 33 days) and 39% (95% CI = 33%45%) in the 60119 days after an updated dose (median interval since updated dose = 74 days) (Table 2). Among adults aged 18-64 years, VE against COVID-19associated ED/UC encounters was 52% (95% CI = 45%58%) in the first 759 days after an updated dose (median interval since updated dose = 31 days) and 45% (95% CI = 34%55%) in the 60119 days after an updated dose (median interval since updated dose = 73 days). Among adults aged 65 years, VE against COVID-19associated ED/UC encounters was 49% (95% CI = 44%54%) in the first 759 days after an updated dose (median interval since updated dose = 33 days) and 37% (95% CI = 29%44%) in the 60119 days after an updated dose (median interval since updated dose = 74 days).

VISION network. Among adults aged 18 years in the VISION network, 37,503 hospitalizations met criteria for inclusion in analyses, including 4,589 case-patients and 32,914 control patients (Table 3). A total of 395 (9%) case-patients and 4,199 (13%) control patients had received an updated COVID-19 vaccine dose. VE against COVID-19associated hospitalization was 53% (95% CI = 46%59%) in the first 759 days after an updated dose (median interval since updated dose = 32 days) and 50% (95% CI = 40%59%) in the 60119 days after an updated dose (median interval since updated dose = 73 days). Among patients aged 65 years, VE against COVID-19associated hospitalization was 54% (95% CI = 47%60%) in the first 759 days after an updated dose (median interval since updated dose = 32 days) and 50% (95% CI = 39%59%) in the 60119 days after an updated dose (median interval since updated dose = 73 days).

IVY network. Among adults aged 18 years in the IVY network, 4,117 met criteria for inclusion in analyses, including 1,194 case-patients and 2,923 control patients. A total of 94 (8%) case-patients and 353 (12%) control patients had received an updated COVID-19 vaccine dose. VE of an updated dose against COVID-19associated hospitalization was 43% (95% CI = 27%56%, median interval since updated dose = 47 days) among adults aged 18 years and 48% (95% CI = 31%61%, median interval since updated dose = 48 days) among adults aged 65 years.

Including control patients who received positive or indeterminant influenza test results added 1,819 control patients to the VISION hospitalization analysis and including control patients who received positive or indeterminant influenza test results or had missing influenza test results added 511 control patients to the IVY hospitalization analysis (Supplementary Table 1, https://stacks.cdc.gov/view/cdc/148434). VE estimates in supplementary analyses including control patients who received positive or indeterminant influenza test results did not differ meaningfully from those in the main analyses for ED/UC encounters (Supplementary Table 2, https://stacks.cdc.gov/view/cdc/148435) or hospitalization (Supplementary Table 3, https://stacks.cdc.gov/view/cdc/148436).

Whole genome sequencing data were available for SARS-CoV-2positive specimens collected in the IVY network during September 21December 15, 2023. Among 952 sequenced specimens, 154 (16%) had XBB.1.5like spike proteins, 550 (58%) had EG.5like spike proteins with an F456L substitution compared with XBB.1.5, 189 (20%) had HK.3like spike proteins with L455F and F456L substitutions compared with XBB.1.5, 57 (6%) had JN.1like spike proteins with more than30 substitutions compared with XBB.1.5, and two (<1%) had other spike proteins. Similarly, among 18,316 SARS-CoV-2positive specimens collected during the same period and sequenced by CDC as part of national genomic surveillance, 2,624 (14%) had XBB.1.5like spike proteins, 9,649 (53%) had EG.5like spike proteins, 3,700 (20%) had HK.3like spike proteins, 2,302 (13%) had JN.1like spike proteins, and 41 (<1%) had other spike proteins.

During September 2023January 2024, in two multisite VE networks, updated 20232024 COVID-19 vaccination provided significant protection against COVID-19associated ED/UC encounters and hospitalization among immunocompetent adults, compared with not receiving an updated vaccine. The comparison group included both unvaccinated persons and persons who had received original monovalent or bivalent doses only; thus, these results support current CDC recommendations for updated COVID-19 vaccination, including among persons who have previously received original monovalent or bivalent COVID-19 vaccines and those who have never been vaccinated, irrespective of previous infection history (1).

Updated COVID-19 vaccines contain the spike antigen from the SARS-CoV-2 Omicron XBB.1.5 virus, which was the predominant variant circulating in the United States during the first half of 2023. Many other XBB lineages cocirculated during fall 2023 that had amino acid substitutions associated with increased escape from neutralizing antibodies, such as EG.5 and HK.3 (5). The JN.1 lineage, a descendent of Omicron BA.2.86, was first detected in the United States in September 2023 and accounted for approximately 65% of circulating lineages by the 2-week period ending January 6, 2024.***** As noted, JN.1 contains more than 30 substitutions in the spike protein compared with XBB.1.5, some of which might be associated with immune escape (5). Although studies have found that updated COVID-19 vaccines elicit broadly cross-protective neutralizing antibodies, including against XBB lineages and JN.1 (57), the pace and frequency with which new SARS-CoV-2 lineages have displaced predecessors underscores the need for ongoing monitoring of COVID-19 VE and for periodic COVID-19 vaccine antigen updates. These analyses include periods when XBB lineages and JN.1 cocirculated to varying degrees in the United States, indicating that receipt of updated vaccines provided protection against COVID-19associated ED/UC encounters and hospitalization due to the variants cocirculating during this period.

Despite different populations, methods, and outcomes, estimates of the effectiveness of updated COVID-19 vaccines were aligned across the VISION and IVY analyses. VE estimates were also similar to those recently published from another CDC VE platform, which measured VE against symptomatic SARS-CoV-2 infection (8), and to a United Kingdom report, which measured VE against hospitalization among patients aged 65 years. Earlier estimates of the effectiveness of updated COVID-19 vaccines against hospitalization in older adults from Denmark (9) and the Netherlands (10) were somewhat higher than those observed in this analysis; however, this is likely due to a shorter interval since updated dose receipt among patients included in the European studies or to differences in study methods. Whereas the maximum interval since receipt of an updated dose was 25 days in the Danish report and 2 months in the Dutch report, persons in the VISION and IVY analyses could have received an updated dose up to 4 months earlier.

In the VISION analysis, there was evidence of waning effectiveness of updated COVID-19 vaccines against ED/UC encounters; however, COVID-19associated hospitalization rates during the analysis period were relatively low compared with previous years, limiting the evaluation of waning VE against hospitalization and precluding estimation of VE against critical illness. Analyses from VISION and IVY during 20222023 showed substantial waning of COVID-19 VE against ED/UC encounters and hospitalization, with VE not significantly different from zero in some strata by 6 months after vaccination, although VE was more sustained against critical illness (2,3) (defined as receipt of invasive mechanical ventilation, intensive care unit admission, or death), with protection lasting well over 1 year after the most recent dose. Continued monitoring of the effectiveness of updated COVID-19 vaccines for expected waning against hospitalization and to determine the durability of VE against critical illness is needed.

The findings in this report are subject to at least five limitations. First, although case-patients were required to meet a CLI definition and to receive a positive SARS-CoV-2 test result, they might have visited EDs or UCs or been hospitalized for reasons other than COVID-19, which could have lowered VE estimates. Second, misclassification of vaccination status was possible, because state registries, EHRs, medical claims data, and self-report might not identify all updated COVID-19 vaccine doses administered, which would likely result in underestimation of VE. Third, analyses did not account for previous SARS-CoV-2 infection, which might provide protection against future COVID-19. VE should therefore be interpreted as the incremental benefit of an updated dose in a population with high levels of infection-induced immunity, vaccine-induced immunity, or both. Fourth, although analyses were adjusted for relevant confounders, residual confounding from other factors, including behavioral modifications to prevent SARS-CoV-2 exposure and outpatient antiviral treatment for COVID-19, is possible. Finally, sample size limitations precluded estimation of lineage-specific VE and stratification of VE by interval since updated dose receipt in the IVY analysis.

In this analysis of the effectiveness of updated COVID-19 vaccines, receipt of an updated COVID-19 vaccine dose provided protection against COVID-19associated ED/UC encounters and hospitalization among immunocompetent adults. CDC will continue monitoring VE of updated COVID-19 vaccines. These results support CDC recommendations for updated 20232024 COVID-19 vaccination. All persons aged 6 months should receive updated 20232024 COVID-19 vaccine.

Monica Dickerson, Abby L. Martin, Ralph D. Whitehead, Jr., CDC; Marcia A. Blair, Shanice L. Cummings, Rendie E. McHenry, Laura Short, Vanderbilt University Medical Center.

Shekhar Ghamande; Robert Gottlieb; Tresa McNeal; Catherine Raver; William Bender; Linda Fletcher; Phillip Heaton; Sheryl Kane; Charlene McEvoy; Sunita Thapa; Gabriela Vazquez-Benitez; Anne Frosch; Lois E Lamerato; Mayur Ramesh; Julie Arnofer; Harith Ali; Johns Hopkins; Bradley Crane; Padma Dandamudi; Kristin Goddard; John Hansen; Julius Timbol; Ousseny Zerbo; Katie Allen; Thomas Duszynski; William Fadel; Colin Rogerson; Nida Qadir; Catia Chavez; Bryant Doyle; David Mayer; Suchitra Rao; Carolina Rivas; Nicholas J. Johnson; Adrienne Baughman; Cara T. Lwin; Jillian P. Rhoads; Kelsey N. Womack; Margaret Dunne; Allison Ciesla; Josephine Mak; Morgan Najdowski; Caitlin Ray

1Coronavirus and Other Respiratory Viruses Division, National Center for Immunization and Respiratory Diseases, CDC; 2Vanderbilt University Medical Center, Nashville, Tennessee; 3Westat, Rockville, Maryland; 4Division of Infectious Diseases and Clinical Epidemiology, Intermountain Healthcare, Salt Lake City, Utah; 5HealthPartners Institute, Minneapolis, Minnesota; 6Kaiser Permanente Center for Health Research, Portland, Oregon; 7Indiana University School of Medicine, Indianapolis, Indiana; 8Regenstrief Institute Center for Biomedical Informatics, Indianapolis, Indiana; 9University of Colorado School of Medicine, Aurora, Colorado; 10Kaiser Permanente Vaccine Study Center, Kaiser Permanente Northern California Division of Research, Oakland, California; 11Department of Biomedical Informatics, Columbia University Irving Medical Center, New York, New York; 12New York-Presbyterian Hospital, New York, New York; 13General Dynamics Information Technology, Falls Church, Virginia; 14University of Michigan, Ann Arbor, Michigan; 15Baylor Scott & White Health, Texas; 16Baylor College of Medicine, Temple, Texas; 17Intermountain Medical Center, Murray, Utah; 18University of Utah, Salt Lake City, Utah; 19University of Iowa, Iowa City, Iowa; 20Wake Forest School of Medicine, Winston-Salem, North Carolina; 21Johns Hopkins University School of Medicine, Baltimore, Maryland; 22Hennepin County Medical Center, Minneapolis, Minnesota; 23Montefiore Medical Center, Albert Einstein College of Medicine, New York, New York; 24University of Washington, Seattle, Washington; 25Baystate Medical Center, Springfield, Massachusetts; 26Oregon Health & Science University, Portland, Oregon; 27Emory University, Atlanta, Georgia; 28Cleveland Clinic, Cleveland, Ohio; 29Stanford University School of Medicine, Stanford, California; 30Ronald Reagan UCLA Medical Center, Los Angeles, California; 31University of Miami, Miami, Florida; 32Washington University in St. Louis, St. Louis, Missouri; 33The Ohio State University, Columbus, Ohio; 34Texas A&M University College of Medicine, Dallas, Texas; 35Henry Ford Health, Detroit, Michigan; 36Yale University School of Medicine, New Haven, Connecticut; 37University of Arizona, Tucson, Arizona; 38Influenza Division, National Center for Immunization and Respiratory Diseases, CDC.

Abbreviations: ED=emergency department; HHS=U.S. Department of Health and Human Services; IVY=Investigating Respiratory Viruses in the Acutely Ill; NH=non-Hispanic; UC=urgent care; VE = vaccine effectiveness; VISION=Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network. * The no updated dose group included all eligible persons who did not receive an updated 20232024 COVID-19 vaccine dose, regardless of number of previous (i.e., original monovalent and bivalent) doses (if any) received. For VISION, Other, NH race includes persons reporting NH ethnicity and any of the following for race: American Indian or Alaska Native, Asian, Native Hawaiian or other Pacific Islander, other races not listed, and multiple races; because of small numbers, these categories were combined. For IVY, Other, NH race includes Asian, Native American or Alaska Native, and Native Hawaiian or other Pacific Islander; because of small numbers, these categories were combined. For VISION, Unknown includes persons with missing race and ethnicity in their electronic health records. For IVY, Unknown includes patients who self-reported their race and ethnicity as Other and those for whom race and ethnicity were unknown. Regions are defined by HHS. States included in each region are available at https://www.hhs.gov/about/agencies/iea/regional-offices/index.html. VISION network sites included were located as follows. Region 5: HealthPartners (Minnesota and Wisconsin) and Regenstrief Institute (Indiana); Region 8: Intermountain Healthcare (Utah) and University of Colorado (Colorado); Region 9: Kaiser Permanente Northern California (California); and Region 10: Kaiser Permanente Northwest (Oregon and Washington). IVY network sites were located as follows: Region 1: Baystate Medical Center (Springfield, Massachusetts), Beth Israel Deaconess Medical Center (Boston, Massachusetts), and Yale University (New Haven, Connecticut); Region 2: Montefiore Medical Center (New York, New York); Region 3: Johns Hopkins Hospital (Baltimore, Maryland); Region 4: Emory University Medical Center (Atlanta, Georgia), University of Miami Medical Center (Miami, Florida), Vanderbilt University Medical Center (Nashville, Tennessee), and Wake Forest University Baptist Medical Center (Winston-Salem, North Carolina); Region 5: Cleveland Clinic (Cleveland, Ohio), Hennepin County Medical Center (Minneapolis, Minnesota), Henry Ford Health (Detroit, Michigan), The Ohio State University Wexner Medical Center (Columbus, Ohio), and University of Michigan Hospital (Ann Arbor, Michigan); Region 6: Baylor Scott & White Medical Center (Temple, Texas) and Baylor University Medical Center (Dallas, Texas); Region 7: Barnes-Jewish Hospital (St. Louis, Missouri) and University of Iowa Hospitals (Iowa City, Iowa); Region 8: Intermountain Medical Center (Murray, Utah), UCHealth University of Colorado Hospital (Aurora, Colorado), and University of Utah (Salt Lake City, Utah); Region 9: Stanford University Medical Center (Stanford, California), Ronald Reagan UCLA Medical Center (Los Angeles, California), and University of Arizona Medical Center (Tucson, Arizona); and Region 10: Oregon Health & Science University Hospital (Portland, Oregon) and University of Washington (Seattle, Washington). ** VISION underlying condition categories included pulmonary, cardiovascular, cerebrovascular, musculoskeletal, neurologic, hematologic, endocrine, renal, and gastrointestinal. IVY underlying condition categories included pulmonary, cardiovascular, neurologic, hematologic, endocrine, renal, gastrointestinal, and autoimmune. The JN.1 predominant period was considered to have started December 24, 2023.

Abbreviations: Ref=referent group; VE=vaccine effectiveness; VISION=Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network. * VE was calculated as (1 odds ratio) 100% with odds ratios calculated using multivariable logistic regression. For VISION, the odds ratio was adjusted for age, sex, race and ethnicity, geographic region, and calendar time (days since January 1, 2021). The no updated dose group included all eligible persons who did not receive an updated 20232024 COVID-19 vaccine dose, regardless of number of previous (i.e., original monovalent and bivalent) doses (if any) received.

Abbreviations: IVY=Investigating Respiratory Viruses in the Acutely Ill; Ref=referent group; VE=vaccine effectiveness; VISION=Virtual SARS-CoV-2, Influenza, and Other respiratory viruses Network. * VE was calculated as (1 odds ratio) 100% with odds ratios calculated using multivariable logistic regression. For VISION, the odds ratio was adjusted for age, sex, race and ethnicity, geographic region, and calendar time (days since January 1, 2021). For IVY, the odds ratio was adjusted for age, sex, race and ethnicity, calendar time in biweekly intervals, and U.S. Department of Health and Human Services region. The no updated dose group included all eligible persons who did not receive an updated 20232024 COVID-19 vaccine dose, regardless of number of previous (i.e., original monovalent and bivalent) doses (if any) received. Some estimates are imprecise, which might be due to a relatively small number of persons in each level of vaccination or case status. This imprecision indicates that the actual VE could be substantially different from the point estimate shown, and estimates should therefore be interpreted with caution. Additional data accrual could increase precision and allow more precise interpretation.

Suggested citation for this article: DeCuir J, Payne AB, Self WH, et al. Interim Effectiveness of Updated 20232024 (Monovalent XBB.1.5) COVID-19 Vaccines Against COVID-19Associated Emergency Department and Urgent Care Encounters and Hospitalization Among Immunocompetent Adults Aged 18 Years VISION and IVY Networks, September 2023January 2024. MMWR Morb Mortal Wkly Rep 2024;73:180188. DOI: http://dx.doi.org/10.15585/mmwr.mm7308a5.

MMWR and Morbidity and Mortality Weekly Report are service marks of the U.S. Department of Health and Human Services. Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services. References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

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Interim Effectiveness of Updated 20232024 (Monovalent XBB.1.5) COVID-19 Vaccines Against COVID-19Associated ... - CDC

The new vaccines that protect older adults against respiratory syncytial virus, or RSV, may be linked to a small increased risk of developing Guillain-Barr syndrome, new data from the Centers for Disease Control and Prevention and the Food and Drug Administration suggest.

At a meeting Thursday of the Advisory Committee on Immunization Practices, vaccine safety experts from the two agencies presented data that showed what appears to be an elevated rate of GBS, as the condition is called, among people who got the Pfizer vaccine, although there were also cases detected among people who got the GSK product.

But the experts cautioned that it is too early to determine if there is a true increased risk of developing GBS after RSV vaccination, or to quantify the size of that risk, if it exists.

Were still in the early uptake phase of these new RSV vaccines, Tom Shimabukuro, the former director of the CDCs immunization safety office, told STAT in an interview after the meeting. Shimabukuro, who recently took a job as deputy director of the CDCs influenza division, presented the GBS data to the ACIP meeting.

Some of these data and findings are based on small numbers of cases and relatively small numbers of doses administered, he said in the interview. And due to uncertainties and limitations, based on these early data we cant establish if there is an increased risk for GBS after RSV vaccination in these individuals 60 and older.

Shimabukuro said the CDC would begin a more in-depth analysis using a different vaccine safety database in March. Better risk estimates will be forthcoming in the coming weeks and months, he said.

GBS is a neurological condition involving muscle weakness and sometimes paralysis. Most people fully recover over time, but some sustain permanent nerve damage. About two-thirds of people who are diagnosed with GBS develop the condition shortly after infection with a virus or a bacterium that causes diarrhea or a respiratory illness. GBS is more common in people aged 50 and older.

Some vaccines appear to increase the risk that a recipient will develop GBS. But teasing out whether there is a true link between a vaccine and GBS can be tricky. And in some cases, even if there is an increased risk of GBS following vaccination, that information has to be assessed in a broader context. For example, while it is thought that there is a small increased risk of developing GBS after flu vaccination among 1 million people who get vaccinated, there may be one or two more cases than one would normally see in a similarly sized group of unvaccinated people its known that contracting flu also increases the risk of developing GBS.

There have been concerns the new RSV vaccines, which were first brought to market last fall, might carry an increased risk of GBS after three cases were detected among people in the vaccine arms of the clinical trials Pfizer and GSK conducted to persuade the FDA to license the products.

The Pfizer vaccine is sold under the brand name Abrysvo while the GSK vaccine is sold as Arexvy.

Vaccine safety analysts at both the CDC and the FDA have been monitoring vaccine safety databases primarily one known as the Vaccine Adverse Events Reporting System, or VAERS looking for safety signals following the initial rollout of the RSV vaccines.

The VAERS database is where doctors and the pharmaceutical companies are supposed to report health events that happen in the hours or days after a person receives a vaccine. The data there cannot establish a cause-and-effect relationship between a vaccination and a health problem, but they can serve as an early warning signal.

By mid-February, CDC analysts had identified and verified 23 cases of GBS among the roughly 9.5 million people who have been vaccinated with one of the two vaccines. Fifteen of those were among people who got the Pfizer vaccine and eight were among people who received the GSK jab. Complicating the issue: 14 of the cases involved people who had received the RSV vaccine at the same time as another vaccine a range of vaccines that included a variety of brands of flu shots and Covid-19 vaccines, as well as shingles vaccine, tetanus-diphtheria and pertussis vaccine, and a rabies shot.

In the 21 days after vaccination, the rate of GBS cases among recipients of the Pfizer vaccine was 4.6 per 1 million doses of vaccine administered. Among GSK recipients, the rate was 1.1 per 1 million. The expected background rate the rate at which GBS occurs among people who get vaccinated with vaccines that dont elevate ones risk of developing GBS is 2.0 cases per 1 million doses in the 21 days after a vaccination, Shimabukuro told the committee.

Reema Mehta, Pfizers vice president and head of risk assessment and management for worldwide safety, told the ACIP the company believes its vaccine is safe, but is conducting four post-marketing safety studies looking for GBS among recipients. We will continue to share our findings with CDC, FDA, and other stakeholders as they become available, she said.

In an email, GSK spokeswoman Alison Hunt noted that the CDC analysis did not suggest there was an elevated rate of GBS among people who had received the companys RSV vaccine. Hunt said GSK is in the process of designing a study to evaluate the risk of GBS after receipt of Arexvy.

CDC vaccine experts told the ACIP that a risk-benefit analysis the agency conducted continues to support use of the vaccines in people aged 60 and older, because of the burden of RSV disease in that population. For every 1 million doses of RSV vaccine given, between 2,400 and 2,700 RSV hospitalizations, 450 to 520 intensive care unit admissions, and 120 to 140 deaths are averted, the agency estimated.

This signal comes at a time when GSK has indicated it hopes to persuade the FDA to expand the license for its RSV vaccine by lowering the age of people eligible to receive the shot to include people aged 50 to 59 who have health conditions that put them at risk of becoming severely ill if they contract RSV.

It also comes as ACIPs RSV work group a subcommittee of members, CDC staff, and outside experts is mulling whether the CDCs recommendation on who should get an RSV vaccine should change. The current policy, approved last fall, recommends the vaccine for people 60 and older if a health care provider believes vaccination would be beneficial. That recommendation called shared decision-making has confused physicians and some would-be recipients, and has probably depressed uptake of the vaccine, survey data suggest.

Amadea Britton, a CDC expert who is one of the leads of the RSV work group, said the group is considering changing that recommendation so that there would be a universal recommendation for some adults, perhaps people aged 75 and older. That would be the equivalent of CDC declaring, These people should all get vaccinated. In that scenario, the recommendation for people younger than that group would be based on individual risk, so would still require a recommendation from a health care provider.

Correction: An earlier version of this story misstated the risk of developing GBS after flu vaccination.

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RSV vaccines may be linked to small increased risk of developing Guillain-Barr syndrome, data suggest - STAT

ABRYSVO, a bivalent vaccine, maintained consistently high protective efficacy for both RSV A and RSV B disease through two seasons after a single dose.

ABRYSVO efficacy was 77.8% against RSV lower respiratory tract disease with three or more symptoms in a second full RSV season in adults 60 years of age or older.

NEW YORK, February 29, 2024--(BUSINESS WIRE)--Pfizer Inc. (NYSE: PFE) today announced top-line ABRYSVO vaccine efficacy and safety data for respiratory syncytial virus (RSV) in adults 60 years of age and older following a second season in the Northern and Southern Hemispheres from the ongoing pivotal Phase 3 clinical trial (NCT05035212) RENOIR (RSV vaccine Efficacy study iN Older adults Immunized against RSV disease). Vaccine efficacy against RSV-associated lower respiratory tract disease (LRTD), defined by three or more symptoms, after disease surveillance in season two was 77.8% (95.0% CI: 51.4, 91.1); vaccine efficacy following season one was 88.9% (95.0% CI: 53.6%, 98.7%)1, which demonstrates durable efficacy after two seasons.

Consistent vaccine efficacy was demonstrated for both RSV A and RSV B after season two with vaccine efficacy against each subtype of 80% for LRTD with three or more symptoms. Vaccine efficacy was also sustained against less severe LRTD, defined by two or more symptoms, from 65.1% (95.0%% CI: 35.9%, 82.0%)1 after season one to 55.7% (95.0% CI: 34.7%, 70.4%) after the end of season two. Vaccine efficacy against RSV-associated LRTD, defined by three or more symptoms, across both seasons after approximately 16.4 months of disease surveillance was 81.5% (95.0% CI: 63.3, 91.6).

No new adverse events were reported through the second RSV season beyond what was reported by subjects in the clinical trial during the first season. Pfizer is conducting post-marketing studies and surveillance programs to inform the safety profile of ABRYSVO.

"We are encouraged by the level of protection that we observed after two full RSV seasons for ABRYSVO," said Annaliesa Anderson, Ph.D., Senior Vice President and Chief Scientific Officer, Vaccine Research and Development, Pfizer. "This new data indicate that broad and durable protection against both types of RSV that cause disease, RSV A and RSV B, is the potential benefit to having a bivalent vaccine."

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Pfizer intends to submit these data to regulatory authorities and vaccine technical committees. The company also intends to publish these findings in a peer-reviewed scientific journal and share them at an upcoming scientific congress.

ABOUT RSVRSV is a contagious virus and a common cause of respiratory illness.2 The virus can affect the lungs and breathing passages of an infected individual and can potentially cause severe illness in young infants, older adults, and individuals with certain chronic medical conditions.3,4,5 In the United States alone, among older adults, RSV infections account for approximately 60,000-160,000 hospitalizations and 6,000-13,000 deaths each year.6,7,8,9,10,11,12,13,14 RSV disease is caused by the respiratory syncytial virus. There are two major subgroups of RSV: RSV A and RSV B. Both subgroups cause disease and can co-circulate or alternate predominance from season to season.

ABOUT ABRYSVOPfizer currently is the only company with an RSV vaccine to help protect older adults, as well as infants through maternal immunization. ABRYSVO is a bivalent vaccine that was designed to provide broad protection against all RSV-LRTD, regardless of the virus subgroup. The RSV fusion protein (F) in the prefusion conformation is a major target of virus infection blocking antibodies and is the basis of Pfizers RSV vaccine. Sequence variability in F between RSV subgroup A and B strains clusters in potent neutralizing antibody binding sites on prefusion F.

In May 2023, the FDA approved ABRYSVO for the prevention of LRTD caused by RSV in individuals 60 years of age or older. ABRYSVO is a bivalent vaccine that was designed to provide broad protection regardless whether strain. This was followed by the ACIPs recommendation of the vaccine for use in adults 60 years of age and older with shared clinical decision making, which occurred in June 2023. In August 2023, the FDA approved ABRYSVO for the prevention of LRTD and severe LRTD caused by RSV in infants from birth up to six months of age by active immunization of pregnant individuals at 32 through 36 weeks gestational age. This was followed in September 2023 with ACIPs recommendation for maternal immunization to help protect newborns from RSV seasonally where the vaccine should be administered from September through January in most of the continental United States.

Also in August 2023, Pfizer announced that the European Medicines Agency (EMA) granted marketing authorization for ABRYSVO for both older adults and maternal immunization to help protect infants. The vaccine has also received approvals from la Administracin Nacional de Medicamentos, Alimentos y Tecnologa Mdica (ANMAT) of Argentina in September 2023; the Medicines and Healthcare products Regulatory Agency (MHRA) of the United Kingdom in November 2023; Health Canada of Canada in January 2024; the Pharmaceutical Administration Bureau of Macau in February 2024; and for maternal immunization to help protect infants by the Ministry of Health, Labour, and Welfare of Japan in January 2024.

Pfizer has also initiated two additional clinical trials evaluating ABRYSVO. One trial is being conducted in children ages two to less than 18 years who are at higher risk for RSV disease.15 A second trial is evaluating adults ages 18 to 59 years at higher risk for RSV due to underlying medical conditions such as asthma, diabetes and chronic obstructive pulmonary disease (COPD), and adults ages 18 and older who are immunocompromised and at high risk for RSV.

INDICATIONS FOR ABRYSVO

ABRYSVO is a vaccine indicated in the US for:

the prevention of lower respiratory tract disease (LRTD) caused by respiratory syncytial virus (RSV) in people 60 years of age and older

pregnant individuals at 32 through 36 weeks gestational age for the prevention of LRTD and severe LRTD caused by RSV in infants from birth through 6 months of age

IMPORTANT SAFETY INFORMATION FOR ABRYSVO

ABRYSVO should not be given to anyone with a history of severe allergic reaction (e.g., anaphylaxis) to any of its components

For pregnant individuals: to avoid the potential risk of preterm birth, ABRYSVO should be given during 32 through 36 weeks gestational age

Fainting can happen after getting injectable vaccines, including ABRYSVO. Precautions should be taken to avoid falling and injury during fainting

Adults with weakened immune systems, including those receiving medicines that suppress the immune system, may have a reduced immune response to ABRYSVO

Vaccination with ABRYSVO may not protect all people

In adults 60 years of age and older, the most common side effects (10%) were fatigue, headache, pain at the injection site, and muscle pain

In pregnant individuals, the most common side effects (10%) were pain at the injection site, headache, muscle pain, and nausea,

In clinical trials where ABRYSVO was compared to placebo, infants born to pregnant individuals experienced low birth weight (5.1% ABRYSVO versus 4.4% placebo) and jaundice (7.2% ABRYSVO versus 6.7% placebo

View the full ABRYSVO Prescribing Information.

About Pfizer: Breakthroughs That Change Patients Lives

At Pfizer, we apply science and our global resources to bring therapies to people that extend and significantly improve their lives. We strive to set the standard for quality, safety and value in the discovery, development and manufacture of health care products, including innovative medicines and vaccines. Every day, Pfizer colleagues work across developed and emerging markets to advance wellness, prevention, treatments and cures that challenge the most feared diseases of our time. Consistent with our responsibility as one of the world's premier innovative biopharmaceutical companies, we collaborate with health care providers, governments and local communities to support and expand access to reliable, affordable health care around the world. For more than 170 years, we have worked to make a difference for all who rely on us. We routinely post information that may be important to investors on our website at http://www.Pfizer.com. In addition, to learn more, please visit us on http://www.Pfizer.com and follow us on Twitter at @Pfizer and @Pfizer News, LinkedIn, YouTube and like us on Facebook at Facebook.com/Pfizer.

DISCLOSURE NOTICE:The information contained in this release is as of February 29, 2024. Pfizer assumes no obligation to update forward-looking statements contained in this release as the result of new information or future events or developments.

This release contains forward-looking information about ABRYSVO, including its potential benefits, plans to submit season two data to regulatory authorities and vaccine technical committees, clinical trials initiated for ABRYSVO in other populations and post-marketing studies and surveillance programs for ABRYSVO, that involves substantial risks and uncertainties that could cause actual results to differ materially from those expressed or implied by such statements. Risks and uncertainties include, among other things, uncertainties regarding the commercial success of ABRYSVO; the uncertainties inherent in research and development, including the ability to meet anticipated clinical endpoints, commencement and/or completion dates for our clinical trials, regulatory submission dates, regulatory approval dates and/or launch dates, as well as the possibility of unfavorable new clinical data and further analyses of existing clinical data; risks associated with interim data; the risk that clinical trial data are subject to differing interpretations and assessments by regulatory authorities; whether regulatory authorities will be satisfied with the design of and results from our clinical studies; whether and when biologic license applications may be filed in particular jurisdictions for ABRYSVO for any potential indications; whether and when any applications that may be pending or filed for ABRYSVO may be approved by regulatory authorities, which will depend on myriad factors, including making a determination as to whether the product's benefits outweigh its known risks and determination of the product's efficacy and, if approved, whether ABRYSVO for any such indications will be commercially successful; intellectual property and other litigation; decisions by regulatory authorities impacting labeling, manufacturing processes, safety and/or other matters that could affect the availability or commercial potential of ABRYSVO; uncertainties regarding the ability to obtain recommendations from vaccine advisory or technical committees and other public health authorities regarding ABRYSVO and uncertainties regarding the commercial impact of any such recommendations; uncertainties regarding the impact of COVID-19 on our business, operations and financial results; and competitive developments.

A further description of risks and uncertainties can be found in Pfizers Annual Report on Form 10-K for the fiscal year ended December 31, 2023, and in its subsequent reports on Form 10-Q, including in the sections thereof captioned "Risk Factors" and "Forward-Looking Information and Factors That May Affect Future Results", as well as in its subsequent reports on Form 8-K, all of which are filed with the U.S. Securities and Exchange Commission and available at http://www.sec.gov and http://www.pfizer.com.

1 Walsh EE, Gonzalo PM, et al. "Efficacy and Safety of a Bivalent RSV Prefusion F Vaccine in Older Adults." The New England Journal of Medicine. April 20, 2023. https://www.nejm.org/doi/full/10.1056/NEJMoa2213836?query=featured_home 2 Centers for Disease Control and Prevention. Respiratory Syncytial Virus Infection (RSV). https://www.cdc.gov/rsv/index.html. Updated December 18, 2020. 3 Centers for Disease Control and Prevention. RSV Transmission. https://www.cdc.gov/rsv/about/transmission.html. Updated December 18, 2020. 4 Centers for Disease Control and Prevention. Respiratory Syncytial Virus Infection (RSV) Older Adults are at High Risk for Severe RSV Infection Fact Sheet. https://www.cdc.gov/rsv/factsheet-older-adults.pdf. 5 Centers for Disease Control and Prevention. RSV in Infants and Young Children. https://www.cdc.gov/rsv/high-risk/infants-young-children.html. 6 Centers for Disease Control and Prevention. RSV Surveillance & Research. https://www.cdc.gov/rsv/research/index.html. 7 Widmer K, Zhu Y, Williams JV, et al. Rates of Hospitalizations for Respiratory Syncytial Virus, Human Metapneumovirus, and Influenza Virus in Older Adults. J Infect Dis. 2012; 206(1):56-62. 8 Branche AR, Saiman L, Walsh EE, et al. Incidence of Respiratory Syncytial Virus Infection Among Hospitalized Adults, 20172020. CID. 2022;74(6):1004-1011. 9 McLaughlin JM, Khan F, Begier E, et al. Rates of Medically Attended RSV among US Adults: A Systematic Review and Meta-analysis. Open Forum Infect Dis. 2022; 9(7): ofac300. 10 Zheng Z, Warren JL, Shapiro ED, et al. Estimated Incidence of Respiratory Hospitalizations Attributable to RSV Infections across Age and Socioeconomic Groups. Pneumonia. 2022;14(1):6. 11 Centers for Disease Control and Prevention. October 2022 ACIP Meeting Slides. ACIP Adult RSV Work Group Considerations. Available at: http://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2022-10-19-20/04-RSV-Adults-Melgar-508.pdf. 12 Thompson WW, Shay DK, Weintraub E, et al. Mortality Associated with Influenza and Respiratory Syncytial Virus in the United States. JAMA. 2003; 289(2): 179.186. 13 Matias G, Taylor R, Haguinet F, et al. Estimates of Mortality Attributable to Influenza and RSV in the United States during 19972009 by Influenza Type or Subtype, Age, Cause of Death, and Risk Status. Influenza Other Respir Viruses. 2014; 8(5):507-15. 14 Hansen CL, Chaves SS, Demont C, Viboud C. Mortality Associated With Influenza and Respiratory Syncytial Virus in the US, 1999-2018.JAMA Network Open. 2022 Feb 1;5(2):e220527. 15 Pfizer Second-Quarter 2023 Earnings Teleconference Presentation, August 1, 2023, page, 24, https://s28.q4cdn.com/781576035/files/doc_financials/2023/q2/Q2-2023-PFE-Earnings-Release.pdf

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Pfizer Announces Positive Top-Line Data for Full Season Two Efficacy of ABRYSVO for RSV in Older Adults - Yahoo Finance

NEW YORK

Older U.S. adults should roll up their sleeves for another COVID-19 shot, even if they got a booster in the fall, federal health officials said Wednesday.

The Centers for Disease Control and Prevention said people 65 and older should get another dose of the updated vaccine that became available in September if at least four months has passed since their last shot. In making the recommendation, the agency endorsed guidance proposed by an expert advisory panel earlier in the day.

Most COVID-19 deaths and hospitalizations last year were among people 65 years and older. An additional vaccine dose can provide added protection ... for those at highest risk, Dr. Mandy Cohen, director of the CDC, said in a statement.

The advisory panels decision came after a lengthy discussion about whether to say older people may get the shots or if they should do so. That reflects a debate among experts about how necessary another booster is and whether yet another recommendation will add to the publics growing vaccine fatigue.

Some doctors say most older adults are adequately protected by the fall shot, which built on immunity derived from earlier vaccinations and exposure to the virus itself. And preliminary studies so far have shown no substantial waning in vaccine effectiveness over six months.

However, the bodys vaccine-induced defenses tend to fade over time, and that happens faster in seniors than in other adults. Ultimately, the advisory committee voted 11 to 1 in favor of recommending a booster.

The committee had recommended COVID-19 booster doses for older adults in 2022 and 2023 as well.

COVID-19 remains a danger, especially to older people and those with underlying medical conditions. There are still more than 20,000 hospitalizations and more than 2,000 deaths each week due to the SARS-CoV-2 coronavirus, according to the CDC. And people 65 and older have the highest hospitalization and death rates.

Some members of the advisory panel said a should recommendation is meant to more clearly prod doctors and pharmacists to offer the shots.

Most people are coming in either wanting the vaccine or not, said Dr. Jamie Loehr, a committee member and family doctor in Ithaca, N.Y. I am trying to make it easier for providers to say, Yes, we recommend this.

In September, the government recommended a new COVID-19 shot recipe built against a version of the coronavirus called XBB.1.5. That single-target vaccine replaced combination shots that had been targeting both the original coronavirus strain and a much earlier version of Omicron than XBB.1.5.

The CDC recommended the new shots for everyone 6 months and older and allowed that people with weak immune systems could get a second dose as early as two months after the first.

Most Americans havent listened. According to the latest CDC data, 13% of U.S. children have gotten the shots and about 22% of U.S. adults have. The vaccination rate is higher for adults 65 and older, at nearly 42%.

In each successive vaccine, the uptake has gone down, said Dr. David Canaday, a Case Western Reserve University infectious diseases expert who studies COVID-19 in older people.

People are tired of getting all these shots all the time, said Canaday, who does not serve on the committee. We have to be careful about over-recommending the vaccine.

But there is subset of Americans those at higher danger of severe illness and death who have been asking whether another dose is permissible, said Dr. William Schaffner, a Vanderbilt University vaccines expert who serves on a committee work group that has been debating the booster question.

Indeed, CDC survey data suggest that that groups biggest worry about the vaccine is whether its effective enough.

Agency officials say that among those who got the latest version of the COVID-19 vaccine, 50% fewer will get sick after they come into contact with the virus compared with those who didnt get the fall shot.

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Older U.S. adults should get another COVID-19 shot, CDC recommends - Los Angeles Times

In a bold move that could forever change the landscape of obesity treatment, Novo Nordisk is venturing into uncharted territory with the development of a 'vaccine-like' version of Wegovy, a popular weight management medication. This innovative approach, which seeks to administer the treatment just once a year, emerges as the biotech sector experiences a dynamic shift, marked by surges in Private Investment in Public Equity (PIPE) transactions and intense competition in the development of GLP-1-based treatments. As we delve into this groundbreaking endeavor, we explore the implications for patients, the biotech industry, and the ongoing battle against obesity.

Currently, Wegovy and similar drugs require weekly doses, a regimen that could be cumbersome for patients and a barrier to adherence. Novo Nordisk's chief scientific officer, Marcus Schindler, sheds light on the company's ambitious plan, highlighting the early-stage considerations needed to create long-lasting GLP-1 molecules. The envisioned treatment aims not only to facilitate weight loss but also to provide cardiovascular benefits with minimal administration, potentially once annually. This radical shift in treatment frequency could significantly enhance patient compliance and overall treatment outcomes.

The exploration into a yearly dose of weight-loss medication coincides with a notable surge in PIPE transactions within the biotech sector. The first two months of the year alone have seen 30 deals raising $4 billion, indicating robust interest and investment in biotechnological advancements. This financial momentum underscores the sector's focus on innovative solutions to pressing health issues, including obesity, a condition that continues to challenge public health systems worldwide. The significant investments also reflect confidence in the potential of biotech firms to deliver groundbreaking treatments that can disrupt existing markets.

While the efficacy of GLP-1 agonist drugs in promoting weight loss is well-documented, concerns over side effects, such as substantial muscle loss, have emerged. Companies like Regeneron Pharmaceuticals are diving into this challenge, aiming to mitigate these downsides and carve a niche in a market with a potential worth of $100 to $150 billion. This development underscores the industry's quest for treatments that not only aid in weight loss but also preserve muscle mass, striking a balance critical to patient health and satisfaction. As the biotech sector continues to evolve, the competition intensifies, driving innovation and offering hope for more effective, user-friendly obesity treatments.

In the face of these exciting developments, the journey of Novo Nordisk's yearly obesity 'vaccine' from concept to reality embodies the biotech sector's relentless pursuit of innovation. As we stand on the brink of a potential revolution in obesity treatment, the implications for patient care, industry dynamics, and the broader fight against obesity are profound. With the promise of annual administration, this pioneering approach could significantly alter the treatment landscape, offering a new beacon of hope for millions struggling with obesity.

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Breaking New Ground: Novo Nordisk's Yearly Obesity 'Vaccine' Could Revolutionize Treatment - Medriva

A new CDC-funded study confirms increased risk of heart problems in young men.

A new large, multi-country study has confirmed what previous smaller studies found: Covid-19 vaccines have risks. In particular, the messenger RNA (mRNA) vaccines from Pfizer and Moderna were associated with increased risk of heart problems for males under 40, and the viral vector vaccine from Astra Zeneca was associated with a significant increase in neurological and hematologic problems. This information ought to be used to update U.S. vaccination recommendations, particularly for young people who have little risk of severe Covid-19 disease or death.

Covid vaccines reduce the diseases severity and risk of death and provide partial, short term measured in a few months protection against infection. But those benefits are less important for groups with a low baseline risk, and they must be balanced against the risks associated with vaccination.

The new study, conducted by the CDC-funded Global Covid Vaccine Safety Project, evaluated the risk of adverse events from the three original Covid-19 vaccines with the highest numbers of doses administered in 99 million vaccinated individuals across eight developed countries Argentina, Australia, Canada, Denmark, Finland, France, New Zealand, and Scotland between December 2020 and August 2023. It calculated observed versus expected ratios for 13 different conditions that previous studies had indicated might be increased following Covid-19 vaccinations.

The study found multiple statistically significant associations among the vaccines and various adverse events. The researchers then applied strict statistical criteria beyond the usual standard of statistical significance to select which of the associations had the highest likelihood of being true, what the authors termed a prioritised safety signal.

The two mRNA vaccines met the prioritized-safety-signal criteria for increased risk of myocarditis (inflammation of the heart muscle) following first, second, or third doses. Both vaccines were statistically associated with an increased risk of pericarditis (inflammation of the sac surrounding the heart), although only the Moderna vaccine met the prioritized-safety-signal criteria.

The Astra Zeneca vaccine was associated with various neurological conditions. But only Guillain-Barr syndrome where a persons immune system attacks their nerves, resulting in tingling, muscle weakness, and sometimes paralysis that usually (but not always) resolves over several weeks met the prioritized-safety-signal criteria. A prioritized safety signal was also found for the Astra Zeneca vaccine and the hematologic condition called cerebral venous sinus thrombosis formation of a blood clot in the brains venous sinuses that prevents blood from draining out of the brain and sometimes leads to a hemorrhage into the brain.

The association of Astra Zenecas viral vector vaccine and neurological and hematologic conditions is of limited significance to the U.S. because Astra Zenecas vaccine was not used in this country. The Johnson & Johnson Covid-19 vaccine was a viral-vector vaccine approved and used here. However, it only accounted for about 3 percent of the vaccines approved in 202021 and administered in the U.S. against the original viral variant; it has been discontinued. The mRNA vaccines from Pfizer (59 percent) and Moderna (38 percent) accounted for nearly all the vaccines administered against the original variant.

The studys confirmation of previous publications finding an association of the two mRNA vaccines with heart problems is important for informing the debate about recommending vaccines in younger people, where the risk/reward balance appears to be different than for older people. The U.S. has moved on from vaccines against the original Covid-19 viral strain. However, the vaccines against newer strains are nearly all made with the same mRNA technology. And while the CDC acknowledges a causal association between mRNA COVID-19 vaccines. . . and myocarditis and pericarditis, it continues to recommend vaccination for everyone six months and older.

The increased risk of cardiac events associated with the two mRNA vaccines is concentrated in younger people, primarily adolescent and young adult males. The U.S. Vaccine Adverse Event Reporting System (VAERS) found cases of post-mRNA vaccination myocarditis were predominantly in young men (82 percent) with the highest risk in males aged 16 to 17 years, followed by males aged 12 to 15 years, and young men aged 18 to 24 years. Cases in individuals of either sex above age 40 were extraordinarily rare.

The cardiac risk to younger people must be balanced against the extremely low risk this group has from Covid-19. From January 1, 2020, to December 21, 2023, children under 17 accounted for less than two-tenths of 1 percent of U.S. Covid-19 deaths. The 1829 age group accounted for just 0.6 percent of Covid deaths. Covid-19 hospitalization rates for younger people have also been a tiny fraction of rates for older people.

Some have justified the recommendations to vaccinate younger people by claiming the risk of myocarditis is greater following Covid-19 infection than after Covid-19 vaccination.But the relevant studies suffer from various flaws. For example, one widely cited systemic review and meta-analysis from Penn State University concluded that the risk of developing myocarditis is seven times higher with a Covid-19 infection than with the Covid-19 vaccine. But the median age of subjects was 49 years old, far above the age of those most likely to have vaccine-related adverse reactions. And the study reviewed findings with all types of vaccines, not just the mRNA vaccines that are most closely associated with myocarditis and that are the predominant vaccine type in the U.S.

An English study is similarly cited often to show that the risk from infection outweighs the risk from the vaccine. It too studied almost all ages (13 and up) and vaccine types. But when the researchers looked at males under 40, they found the risk as measured by excess cardiac events per million vaccinated with a first dose of Moderna or a second dose of Pfizer were roughly equal to the excess cardiac events per million infected. And the excess events per million vaccinated following a second Moderna dose were about six times the excess events per million infected. Even though women appear to be at far less cardiac risk than men, the researchers found the excess events per million after a second Moderna dose in women under 40 was about equal to the excess events per million infected.

Importantly, these studies comparing post-vaccine and post-infection rates never acknowledge that their ratios are conditional on certain events taking place, i.e., receiving a vaccine or becoming infected. If the recommendation is that everyone six months or above be vaccinated, then everyone will be subjected to the risk of myocarditis and pericarditis. But not every unvaccinated person will be infected and exposed to cardiac risks.

The best method of assessing what percentage of people were infected is serological studies to detect specific antibodies against SARS-CoV-2, the virus that causes Covid-19.Antibodies against the nucleocapsid-protein, as opposed to different antibodies resulting from vaccination, signify previous infection.

A CDC seroprevalence study in the United States showed variance across different regions, but in nearly all jurisdictions, less than 10 percent of people in the U.S. had antibody evidence of previous SARS-CoV-2 infection through September 2020 the first year of the pandemic when there was no vaccine. A seroprevalence study in Germany over January-November 2020 found just 1.7 percent of residents were infected. A later study with repeated samplings over time found infection-induced SARS-CoV-2 seroprevalence in the U.S. increased from 8.0 percent in November 2020 to 58.2 percent in February 2022, likely reflecting the emergence of the new, more transmissible Delta and Omicron viral variants. Still, after three years of pandemic (January 2020 to December 2022), one in four Americans ages 16 and above had not yet been infected.

Covid-19 vaccines are being promoted for annual administration, hence the myocarditis risk from vaccines should be compared to the risk of being infected over a year. This annual infection percentage will vary depending on the transmissibility of the particular variant then circulating. The studies discussed above suggest this could range from 10 percent, as in the first pandemic year, up to about a 50 percent infection rate in years with particularly transmissible variants. In other words, somewhere between one in ten and one in two people will be subject to the myocarditis and pericarditis risks associated with infection in a given year.

If half of unvaccinated people would be infected over a year, the post-infection myocarditis rate would have to be more than twice the post-vaccination rate to justify recommending that all people (including younger people) be vaccinated. And if only one in ten people would be infected, the post-infection myocarditis rate would have to be ten times the post-vaccine rate. Yet we know from the English study cited above that for woman and especially men under 40, the myocarditis risks from the mRNA vaccines are equal to or higher than the risk after infection.

This new study confirms that the CDC should revise its Covid-19 vaccine guidelines. The children at highest Covid-19 infection risk are newborns, for whom vaccines are neither approved nor recommended. Vaccination recommendation for those aged six months to 18 should be limited to the subpopulation within this age group that is most at risk, such as children with chronic medical conditions (such as Type 1 diabetes, obesity, and cardiac and circulatory congenital anomalies) who are far more likelythan otherwise healthy children to experience severe Covid-19 illness, hospitalization, and death.And CDC should advise particular caution before using the mRNA vaccines in adolescent and young men who are most susceptible to post-vaccination cardiac events. Ultimately, all patients, but especially those with complex medical histories, should consult their physicians to balance the risks and benefits of Covid vaccination.

Much of the world hasdecidedthat healthy young people do not need Covid-19 vaccinations, that the costs outweigh the benefits. The time has come for the U.S. to reach the same conclusion.

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Covid Vaccines: An Update on Balancing Risks and Benefits - National Review

Back in the summer of 2020, people could hardly wait for COVID-19 vaccines to be developed so that the pandemic would end. Within a few months, people were starting to report side effects such as Bells palsy or a false-positive result on mammograms. A new study published in the journal Vaccine reveals some interesting discoveries about the side effects of COVID-19 vaccines (Vaccine, Feb. 12, 2024).

This study, called the Global Vaccine Safety Project, included 99 million people from eight countries. Australia, Canada, Argentina, Denmark, Finland, France, New Zealand and Scotland participated. All vaccinated large numbers of people and have good health records for tracking the outcomes.

In general, serious side effects were rare. The researchers predicted how frequently a severe complication might occur based on the rates before the pandemic began. For example, they estimated rates of myocarditis, or inflammation of the heart muscle, in a healthy unvaccinated population. This problem was twice as common following vaccination. Nonetheless, there were relatively few cases.

Guillain Barr syndrome, a neurological complication that causes temporary paralysis, was more common after the AstraZeneca vaccine. The researchers predicted 76 cases of Guillain Barr in healthy unvaccinated people. They actually observed 190 cases. Thats about 2.5 times more than baseline.

Another serious, but rare complication was acute disseminated encephalomyelitis following the Moderna vaccination. Scientists expected 2 cases among 10 million people vaccinated. Instead, they reported 7.

The conclusion seems to be that COVID vaccines do indeed cause vascular and neurological adverse reactions, but the overall incidence is low. An independent study of COVID-19 vaccines demonstrated that vaccinated individuals have a reduced risk for severe outcomes, including Long COVID (Vaccines, Feb. 2024).

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Study Reveals Side Effects of COVID-19 Vaccines - The People's Pharmacy

CLAIM

No childhood vaccine has ever been through a double blind placebo controlled trial.

DETAILS

Factually inaccurate: There are several blinded, placebo-controlled randomized trials for vaccines that appear in the childhood vaccine schedules of many countries, like the U.S. and Canada. Such trials have been conducted for the vaccines against measles, polio, flu, pneumococcus, human papillomavirus and more.

KEY TAKE AWAY

Randomized controlled trials are commonly held up as the gold standard for determining the safety and efficacy of a medical intervention, like a vaccine or a drug. Saline placebo-controlled trials are sometimes used to test a new vaccine, but such trials arent always practical or ethical to do. For instance, when testing a new vaccine against a disease for which there are existing, effective vaccines, such a trial would leave the placebo group unprotected from the disease. In such cases, it is considered acceptable to compare the new vaccine with an existing one.

Its important to be aware that this claim commonly goes hand in hand considering only saline solution (a solution of salt and water) as a valid placebo, rather than a solution of vaccine adjuvant without the active ingredient. The basis for this belief is that only saline has no effect on living beings, per the definition of a placebo. This is incorrect, as pediatrician Paul Offit pointed out in this article.

In any event, this provides those opposed to vaccination with a justification for ignoring existing studies on vaccine safety that didnt use a saline placebo. It also enables them to undermine confidence in vaccine safety, by implying that the true safety of childhood vaccines has never been properly evaluated.

There are circumstances in which using a saline placebo isnt the ideal choice for a vaccine trial, which this review will delve into later. That said, the claim is inaccurate. As we will show, there are actually numerous childhood vaccine trials that compared the vaccine to a saline placebo.

Double-blind, placebo-controlled randomized trials are commonly considered the gold standard for determining whether a medical intervention, like a vaccine or a drug, is safe and effective.

Double-blind means that neither the researchers nor the trial participants know whether they received the placebo or the treatment. This is done because the knowledge that one group or another received the treatment may influence the way researchers interpret the results and the way that participants behave.

Placebo-controlled means that the trial includes a group that doesnt receive the treatment being tested. Instead, this group may receive an injection of saline or a formulation of the tested intervention that lacks the active ingredient. This helps to reduce the influence of the placebo effect on the trial. If the placebo group and the treatment group both show the same outcome, then the treatment is considered to be ineffective.

Randomized means that participants in the trial are assigned to the placebo or treatment group in a random manner. This helps to reduce differences between the two groups, such as age, sex, and state of health, that could potentially influence the effect being observed. This way, any effect observed can be more reliably attributed to the treatment given, rather than differences between the groups characteristics.

The Instagram post didnt specify which childhood vaccine schedule it was referring to, but childhood vaccine schedules across the world generally tend to include many of the same vaccines. Some of these are the measles, mumps and rubella vaccine, the polio vaccine, and the flu vaccine. However, differences in the age at which a vaccine is given, the vaccine manufacturers, and the number of doses do exist from country to country.

For readers interested in comparing childhood vaccine schedules in different countries, the World Health Organization offers a tool to do so.

Dan Freedman, a pediatric neurologist at UT Health Austin, refuted the claim in a Twitter thread from 2019. He pointed to several blinded, saline placebo-controlled trials for various childhood vaccines, such as measles, polio, flu, pneumococcus, and human papillomavirus (HPV)[1-8]. None of the trials detected health problems associated with the tested vaccines.

And a search on PubMed, a repository of studies in health and medicine that is maintained by the U.S. Library of Medicine, will also turn up multiple studies showing that several vaccines on the childhood vaccination schedule have indeed been tested in double-blind, saline placebo-controlled randomized trials.

In summary, the claim that there are no blinded, saline placebo-controlled randomized trials for childhood vaccines is inaccurate.

Those opposed to vaccines sometimes change tack, asking why there exists no double-blind, saline placebo-controlled trial for the entire childhood vaccine schedule.

In a 2013 review of the U.S. childhood vaccination schedule, the U.S. Institute of Medicine had considered the feasibility of conducting such a trial. But they concluded that it would not only be unfeasible but highly unethical[9].

Firstly, this would consign unvaccinated children to an elevated risk of severe illness and even possible death should the child contract a vaccine-preventable disease. Secondly, this would also place other unprotected people in the community at risk of diseasesuch as immunocompromised people and babies too young to be vaccinated. Thirdly, the existing evidence doesnt show that the current vaccine schedule is unsafe, raising questions about the necessity of doing such a trial.

Overall, the committee that authored the review considered that a saline-controlled randomized trial of the childhood vaccination schedule would pose an unacceptable risk for children and the community at large, while offering no clear benefit.

There are times when saline placebo-controlled trials arent practical or ethical to do. A WHO expert panel delved into this topic at length in this article, documenting their recommendations regarding the use of a placebo in vaccine trials[10].

For example, among the most common side effects of vaccination are fever, soreness at the injection site, and headache. However, a saline placebo doesnt produce these effects, meaning it will be obvious to both the researchers and participants which group did receive the vaccine. This makes blinding difficult to maintain.

And as epidemiologist Ren Najera explained in his article for the website History of Vaccines, having a saline placebo-controlled group means that the placebo group will be left unprotected from a potentially serious disease.

This would be acceptable if no intervention against the disease existedas was the case during the 1954 polio vaccine field trialbut would be unethical to do if an effective vaccine against the disease already exists.

This is why new formulations of existing vaccines can be compared to an earlier formulation that was previously tested and found to be safe and effective, rather than to a saline placebo. This was the case for a study of Prevnar-13, which was compared to its predecessor Prevnar-7[11]. Both are pneumococcal conjugate vaccines against the bacterium Streptococcus pneumoniae.

In fact, comparing a new vaccine to an earlier one can also make the trial better equipped to answer certain questions about the usefulness of the new vaccine.

When we already have existing interventions that are safe and effective, we dont just want to find out if a newly developed intervention works better than saline. We also want to know whether it works better than what we already have. Therefore, testing a new vaccine against an existing one can provide more useful information than testing it against a saline placebo.

The Instagram post also references the book Turtles All The Way Down. Written anonymously, it was co-edited by Mary Holland, the president of anti-vaccine organization Childrens Health Defense. The book propagates numerous anti-vaccine talking points, which were debunked by cardiologist Francis Han. His debunking is compiled in this Twitter thread.

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Various childhood vaccines have been tested in saline placebo-controlled randomized trials, contrary to claims by ... - Health Feedback