Category: Covid-19 Vaccine

The second Global COVID-19 Summit, co-hosted by United States, Belize, Germany, Indonesia, and Senegal, convened over partners and organizations from around the world to accelerate collective efforts to get shots into arms, enhance access to tests and treatments, protect the health workforce, and finance and build health security for future pandemics and other health crises.

The Summit garnered new financial commitments totaling $3.2 billion, not yet announced, above and beyond pledges made to date in 2022. This includes nearly $2.5 billion for COVID-19 and related response activities and $712 million in new commitments toward a new pandemic preparedness and global health security fund at the World Bank. (Note: This builds on $250 million previously pledged for this fund.) We encourage partners to join, as much more is needed to control COVID-19 and build better health security.

Commitments[1] from Government, Other Partners, and Entities

Note: Country text is being validated with host governments and is not yet final.

Commitments[2] from Non-Governmental Organizations, Private Sector, Philanthropies

In addition, we have received commitments from more than 50 organizations, including local and international non-governmental organizations, businesses, philanthropies, advocacy groups, faith-based organizations, and other members of civil society. To date, new commitments in 2022 outlined below exceed $700 million for vaccinating the world, saving lives now, and building better health security.

[1] All commitments made in 2022 are counted toward the goals of the 2nd Global COVID-19 Summit. Of these, approximately $3.1 billion were raised in new funds, not yet announced.

[2] All commitments made in 2022 are counted toward the 2nd Global COVID-19 Summit. Of these, approximately $700 million was raised in new funds, not yet announced.

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2nd Global COVID-19 Summit Commitments - The White House

Coronaviruses belong to the Coronaviridiae family in the Nidovirales order. Bats were considered to be the only reservoir, and the first animal to be documented was the Chinese horseshoe bats [1-3]. The human-to-human transmission of the virus occurs due to close contact with infected persons, and aerosols generated during coughing or sneezing can penetrate the human body during inhalation through the nose or mouth [4]. The earliest case was documented in December 2019, and it is the seventh member of the coronavirus family to infect humans [5]. The International Committee on Taxonomy of Viruses (ICTV) named the virus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease coronavirus disease 2019 (COVID-19). The higher transmission rate of SARS-CoV-2 could be a genetic recombination event at the S protein in the RBD region [4]. The virus undergoes mutations resulting in variants such as B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma), B.1.617 (delta), and the newer variant omicron (B.1.1.529). Omicron has more than 30 deletions and is considered to be a heavily mutant variant that reduces vaccine-mediated immunity [6]. Vaccines are the only tool to control this pandemic outbreak as no specific therapies have been introduced to date. Numerous vaccines have been manufactured, and this article provides information about COVID-19 vaccines and their efficacy against coronavirus variants.

Coronavirus is an enveloped virus approximately 120 nm in diameter with a single-stranded RNA genome. The RNA genome consists of a 5 methyl-guanosine cap, poly (A) tail, and 29,903 nucleotides. It consists of an open reading frame (ORF) encoding non-structural proteins for replication, four structural proteins (spike, envelope, membrane, nucleocapsid), and numerous accessory proteins. The spike glycoprotein binds to angiotensin-converting enzyme 2 (ACE2) in humans for cell entry. The spike protein is cleaved by host proteases into S1 and S2 subunits where S1 is responsible for receptor recognition and S2 for membrane fusion. S1 can be divided into the C-terminal domain and N-terminal domain, with the C-terminal domain showing a stronger affinity for human ACE2. After attachment, the conformational change in the S protein facilitates the fusion of the virus envelope with the cell membrane. The viral RNA genome is released into the cytoplasm and translated into viral replicase polyproteins pp1a and pp1ab3 which are cleaved into small products by virus-encoded proteinases. The polymerase transcribes a series of subgenomic mRNAs by discontinuous transcription which are finally translated into viral structural proteins (S, E, M, N proteins). The N protein combines with the positive-stranded genomic RNA to form a nucleoprotein complex. The structural protein and nucleoprotein complex are assembled within the viral envelope and then released from the infected cell [5].

The glycoprotein spikes on the outer surface of the virus are responsible for the attachment and entry of the virus into host cells. The receptor-binding domain (RBD) is loosely attached among viruses and this is how it infects multiple hosts. Coronavirus depends on cellular proteases such as human airway trypsin-like protease (HAT), cathepsins, and transmembrane protease serine 2 that split the spike protein and help in further penetration. Research on animal studies has revealed that mutation atspike glycoprotein is responsible for severe infection and that therapeutic agents must target spike glycoproteins

Broad-spectrum antibiotics and antiviral drugs were initially used; however, remdesivir has shown promising results. The blood plasma from recovered patients has been injected into infected patients and has shown rapid recovery. Monoclonal antibodies (CR3022) had been found to bind with the spike RBD of SARS-CoV-2 without overlapping with the ACE2 receptor-binding motif. The major hurdle in creating a vaccine is to overcome cross-resistance. Many companies such as Moderna Therapeutics, Inovio Pharmaceuticals, Novavax, Vir Biotechnology, Ster Mirna Therapeutics, Johnson & Johnson, VIDO-Intervac, GeoVax-BravoVax, Clover Biopharmaceuticals, Curevac, and Codagenix had been working for the development of vaccines against COVID-19 [4].

RNA/DNA Vaccines

It uses the host cells transcription and translation processes to express the vaccine antigen that is encoded by the injected nucleotide. COVID-19 RNA-based vaccines are delivered in lipids, and the production is a very quick process [7]. However, freezing huge amounts of the vaccine is challenging [8]. The mRNA-1273 vaccine administered in lipid particles that encode for spike protein triggered a good antibody response [9].

Viral Vector-Based Vaccines

The genetic sequence of the foreign viral antigen inserted into the genome is the baseline of viral vector vaccines. This antigen is either secreted inducing B-cell/antibody response or digested within the target cells inducing a potent CD8+T cell response [10]. However, the vaccine could be neutralized if the vaccinated individuals have pre-existing antibodies against the vector virus. The recent viral vector vaccine against COVID-19 is mostly adenovirus-based. Antibody and T-cell responses were increased on day 28 after vaccination even after its reduction with the presence of pre-existing anti-adenovirus antibodies [11]. ChAdOx1, also known as AZD1222 (Covishield), has increased antibody titers after a booster dose at 28 days [12].

Protein-Based Vaccines

Protein-based vaccines/inactivated vaccines with aluminum salt adjuvants are currently used in routine childhood immunization. One such vaccine for COVID-19 is PiCoVacc, also called CoronaVac, for which clinical trials are ongoing in healthy individuals and the elderly population [13,14]. -propiolactone inactivated SARS-CoV-2WIV04 is another alum-adjuvanted strain with more antibody titers, but these types of vaccines have a chance of eliciting antibody enhancement of disease [15,16]. The other adjuvant vaccines in the trial are the adjuvanted S-trimer vaccine (SCB-19) and subunit vaccine NVX-CoV2373 adjuvanted with matrix-M1 saponins [17].

Vaccines Based on Accentuated SARS-CoV-2 Viruses

This is the most traditional technique where the virus has been weakened so that it will not cause the disease. Though it is effective in strengthening the immune system and inducing a strong immune memory, none of the vaccines for COVID-19 have reached the stage of clinical trials [18].

Vaccines Based on Inactivated SARS-CoV-2 Viruses

This vaccine is based on killed viruses but has a short immune memory. This is not only designed to direct against the spike protein but also many other SARS-CoV-2 antigens. CoronaVac and Sinopharm from China and Covaxin from India were successfully administered to the population after completing phase III trials [18].

Vaccines Based on SARS-CoV-2 Proteins

The vaccines are based on the proteins present on the surface of microbes that are produced in vitro with the help of DNA recombinant technology. The targets of these vaccines are the spike protein and, to some extent, nucleoprotein. Novavax from the United States and Co-VLP have completed phase III trials and have been administered to the population in two doses [18].

Naked DNA-Based Vaccines

DNA plasmids enter human cells after vaccination and induce cells to produce the target protein for a while, thus stimulating the production of antibodies and activation of killer T-cells. Although DNA vaccines are used in the veterinary field, none of them have been administered to humans. However, Inovio from the United States and Genexine from Korea are under trial [18].

mRNA-Based Vaccines

mRNA vaccines induce the cell to produce antigen proteins coded by the mRNA where it is carried by liposomes as nanoparticles, unlike DNA-based vaccines. Pfizer from the United States, Moderna from the United States, Arcturus Ther from Singapore, and CureVac from Germany have been administered to the population after passing clinical trials successfully [18]. In addition, an inhaled form of vaccine from the University of Oxford, UK, has not yet reached phase III trial.

Vaccines Based on Viral Vectors

The DNA coding for the spike protein is inserted into the virus as the virus has the ability to induce immunity by delivering mRNA into the cells. Sputnik from Russia, Covishield from India, Johnson & Johnson from the United States, and Ad5-nCoV use viral vectors to target spike protein [8].

Vaccine efficacy is generally reported as relative risk reduction (RRR) which uses the relative risk (RR) that uses the ratio of attack rates with or without a vaccine, whereas absolute risk reduction (ARR) uses the whole population. However, ARR tends to be ignored as it gives much less effect than RRR. Efficacy provides the RRR of 95% for the Pfizer-BioNTech, 94% for Moderna-NIH, 91% for Gamaleya, 67% for Johnson & Johnson, and 67% for AstraZeneca Oxford vaccines. However, the spectrum entirely changes when the effectiveness of a vaccine is calculated in terms of the number needed to vaccinate (NNV) to prevent one more case of COVID-19, with 81 for Moderna-NIH, 78 for AstraZeneca Oxford, 108 for Gamaleya, 84 for Johnson & Johnson, and 119 for Pfizer-BioNTech vaccines [19].

BNT162b2/Pfizer/BioNTech was the first vaccine approved by the European Medicines Agency against COVID-19 which is administered intramuscularly after dilution in a cycle of two doses 21 days apart [20,21]. Preclinical data include the investigation of immunogenicity and antiviral properties in mice and non-human primates, which proved that the BNT162b2 vaccine protected the lungs of immunized rhesus macaques from COVID-19 [22]. In a phase I/II study, where BNT162b2 was administered to adults, the geometric mean concentrations of RBD-binding immunoglobulin G (IgG) were high after 21 days of the first dose (534-1778 U/mL) when compared to the human convalescent serum (HCS 602 U/mL) after 14 days of the infection confirmed by polymerase chain reaction (PCR). This vaccine showed 95% efficacy and proved that early protection occurs 12 days after the first dose. Another study was performed to evaluate the humoral and adaptive immune response for BNT162b1 from phase I/II studies, in which GMC of anti-RBD antibodies were more in vaccinated individuals (3,920-18,289 U/mL) when compared to HCS (602 U/mL) [23,24]. Further, the efficacy of the vaccine against variants was also tested which shows high neutralizing capacity in all variants, with increased CD4+ and CD8+ RBD-specific T-lymphocytes [25]. However, BNT162b2 was recommended as it is associated with lower incidence and severity of systemic complications when compared to BNT162b1. A two-dose regimen of BNT162b2 conferred 95% efficacy against COVID-19 in a study conducted among 43,448 participants who were injected with the COVID-19 vaccine and saline placebo. Though the efficacy after the first dose was only 51%, it gradually increased to 91% within the first seven days of the second dose [26]. The vaccine efficacy among participants with hypertension also yielded an efficacy of 94.6%, consistent with other participants [27]. Another study amonghealthcare workers in Israel to evaluate the efficacy was found to be 30% in 1-14 days and 75% in 15-28 days [27-29]. In another study, the efficacy in preventing hospitalization after severe infection was found to be 80%, and a single dose helped in preventing death by 85%[30-32].

The Sputnik V vaccine is a vector vaccine based on adenovirus DNA administered over a course of two days, initially produced in Russia. In the previous study, the efficacy of the Sputnik vaccine with two vector components, namely, recombinant adenovirus type 26 (rAd26) and adenovirus type 5 (rAd5), manufactured in two formulations - frozen (0.5 mL) and lyophilized (1 mL of sterile water per dose) was demonstrated. There was increased production of CD4+ and CD8+ after administration of the frozen form than of the lyophilized form, and there was also increased production of interferon-gamma (IFN-) in all vaccinated individuals. The titer of neutralizing antibodies matches the convalescent human serum of those who recovered from recent infection [33]. The phase 3 trial of the Sputnik vaccine gives an efficacy of 91.6% (confidence interval (CI) = 95%), and, interestingly, it was 91.8% for older adults above 60 years. However, initially, the efficacy was 73.6% till 21 days after the first dose [33,34]. In another study where the vaccine was administered in older individuals after the first dose, the efficacy was found to be 78.6% of laboratory-confirmed SARS-CoV-2 infections, 94% in hospitalization, and 93% in preventing death among them, thus delaying the second dose can be followed to increase neutralizing antibodies [35]. The vaccine resists the variants of the COVID-19 virus with a 6.1-fold reduction in the neutralizing activity [36].

Covishield/AZD1222/ChAdOx1 is a viral vector intramuscular vaccine manufactured by the Serum Institute of India and is administered in two doses. In a study among 52 healthy individuals who received the second dose after 56 days of the first dose, there were no systemic reactions such as pyrexia as in the first dose [37-39]. After the first dose, discrete populations of T-cells, B-cells, and natural killer (NK) cells were detected. There was no sex difference and association between the age and magnitude response in this study among individuals aged from 18 to 55 years. The IgG spike was similar to that of plasma from convalescent patients with SARS-CoV-2. The CD4+ and CD8+ secrete antigen-specific cytokines with CD8+ T-cells expressing CD107a, which is a degranulation marker, indicating its cytotoxic effect after vaccination. However, the predominant cytokines were IFN- and CD8+ cells [38]. The levels of anti-spike IgG were found to be lower when the individuals received half-booster doses; however, it was increased to 10-fold when they received prime booster doses [38,39]. The total antigen-specific T-cell response was increased after 14 days of vaccination [37]. The second dose either given after 28 days or 56 days after the first shot provides a similar response in producing the antibodies [39]. Preclinical studies in Rhesus macaques prevent SARS-CoV-2-mediated pneumonia [40]. After administration of Covishield with booster dose in older adults, microneutralization assay peaked by day 42, the antibody titers were not raised after the booster dose in all age groups, and the immunization response in older adults was very similar to young adults. The anti-spike IgG levels correlate with neutralizing antibody titers for all age groups (18-55, 56-69, 70, and older) [41]. Another study with 23,848 participants across different parts of the world such as the UK, Brazil, and South Africa was conducted to estimate the efficacy. Interestingly, those who received two standard doses had lesser efficacy (70.4%) than those who received a low dose (2.2 1,010 viral particles) vaccine at the first dose followed by the standard booster dose (5 1,010 viral particles) (90%). The second dose within six weeks of the first dose provides less efficacy (53.4%) than the one with more than six weeks between the first and second dose (65.4%). Thus, delaying the second dose helps in increasing the efficacy, as well as overcoming the low availability of vaccines in this pandemic situation [42].

Covaxin/BBV152 is an inactivated virus-based COVID-19 vaccine formulated by Bharat Biotech and administered intramuscularly in two doses similar to any other COVID-19 vaccine. In a study with 375 healthy individuals, the vaccine (3 g and 6 g with IMBG) was given randomly to evaluate the immune response and efficacy. The most common adverse effects reported were pain in the injection site (5%), fatigue (3%), and headache (3%). The IgG titers were increased after the second dose, and the efficacy was 87.9% with 3 g and 91.9% with 6 g, thus IgG titers do not have any effect on the concentration [43]. However, both the doses elicit CD3+, CD4+, and CD8+ leading to IFN- production, and the neutralizing antibodies remained elevated for three months after the second vaccination. In the follow-up study with 380 participants, the neutralizing antibody titers were similar to the convalescent serum, and the same results were obtained in other studies [31,44,45].

The Janssen/Johnson & Johnson is another viral vector-based vaccine that requires only a single dose. The first dose of the Johnson & Johnson vaccine provides an efficacy of 76.7% after 14 days of administration of the first dose. However, a phase 3 trial showed an efficacy of 66.9% after 14 days and 66.1% after 28 days of vaccination. The efficacy of preventing severe infection was 76.7% after 14 days and 85.4% after 28 days which is quite high [46,47]. However, other studies reveal that it was 66% effective in preventing symptomatic COVID-19, 85% in severe COVID-19, and 100% in preventing hospitalization or death [48,49].

The virus mutations have resulted in variants such as B.1.1.7 (alpha), B.1.351 (beta), P.1 (gamma), B.1.617 (delta), and the newer omicron (B.1.1.7), which has enhanced transmissibility and fatality rates [50-52]. The S genes of B.1.351 and P.1 have various mutations and that might be the reason for re-infection by vanishing neutralizing antibodies formed during infection by the alpha variant [53,54]. The recent delta variant is characterized by spike protein mutations. P681R is at the S1-S2 cleavage site, and this variant has replication at its peak with higher transmissibility [55]. The first case of the recent omicron (B.1.1.529) with mutations in the RBD and NTD first emerged in South Africa in November 2021. The risk of reinfection is 5.4 times greater with omicron than that of the delta variant [56,57]. The emergence of these variants globally is illustrated in Figure 1.

The efficacy of single doses of BNT162b2 and ChAdOx1nCoV-19 vaccines against the delta variant is approximately 36% and 30%, respectively. However, the second dose increases the efficacy to 88% and 67%, respectively. A study from Scotland revealed that the efficacy of Covaxin is 81% against the alpha variant and 61% against the delta variant [58]. The efficacy of Covaxin against the delta variant is around 65% according to a phase 3 trial study [59]. The efficacy of Pfizer and AstraZeneca after the second dose was found to be 78% and 61%, respectively [60]. However, Pfizer-BioTech and Oxford-AstraZeneca vaccines were highly efficacious against delta variants but dropped over time [61]. Alpha variants have a 1.8-2-fold reduction in neutralizing antibodies of Moderna, Sputnik, and Novovax vaccines. The neutralizing capacity for the P.1 variant among vaccinated individuals was reduced by 6.7 for the Pfizer vaccine and 4.5 for the Moderna vaccine [62]. Delta variants have a 7-10 fold reduction in neutralizing antibody levels of Pfizer, Moderna, and Sputnik, and a 2-3-fold reduction in the case of Covishield and Covaxin; however, the sample study with Johnson and Johnson showed that it neutralizes the delta variant similar to Sputnik. However, Sputnik against B.1.351 variant showed a 6.1-fold reduction in neutralizing antibodies [63]. In another study, sera fromAstraZeneca recipients showed a 4.1-32.5-fold reduction in neutralizing activity against B.1.351 [64]. However, the reduction in the neutralizing antibodies in the sera of individuals receiving Moderna and BioNTech vaccines was 6.5-8.6-fold [62]. ZyCov-D is another DNA vaccine that is claimed to be effective against the delta variant in clinical trials [65]. The efficacy of these vaccines and the reduction in the neutralizing capacity of COVID-19 vaccines against variants of COVID-19 are presented in Table 1 and Table 2. Vaccinated people affected with the alpha variant had a lower viral load, whereas vaccinated individuals infected with the delta variant had a higher viral load. Thus, irrespective of the vaccine administered, the efficacy is reduced against the delta virus, but still effective in reducing fatality. Until October 2021, globally, 676 crore doses were given and 288 crore individuals were fully vaccinated, that is, 36.9% of the population. In India, 99.7 crore doses were administered to 29.2 crore individuals (21.1%) who are fully vaccinated [66]. The research is still ongoing regarding vaccine efficacy against omicron; however, researchers have found that two doses of the Pfizer vaccine provide 70% infection against hospitalization and 33% against infection [67]. As the efficacy wanes over time, researchers are insisting on having a third dose/booster dose which helps in boosting the efficacy. Recent studies have focused on the combination of booster doses for better efficacy. There was no increase in the efficacy against omicron even after the two doses of AstraZeneca, and this variant reduced the efficacy of Pfizer/Moderna to 10% even after two doses which increased to 40-50% and the effectiveness against hospitalization also increased to 88% after the booster dose [68]. The booster dose increases the neutralizing antibody titers by 25-fold with the Pfizer vaccine [69]. The recent study ofvaccineBNT162b2 among the pediatric population (5-11 years) showed 95% efficacy after two doses [70]. Because the efficacy of vaccines against the omicron variant is under investigation, the data available to date is presented in Table 3; however, this might change as studies are published.

Excerpt from:

COVID-19 Vaccines and the Efficacy of Currently Available Vaccines Against COVID-19 Variants - Cureus

Since the initial global outbreak of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causal agent of the coronavirus disease 2019 (COVID-19) pandemic, a continuous evolution of the virus has been observed. The emergence of new SARS-CoV-2 variants, which have been classified as variants of concern (VOC) and variants of interest (VOI), has reduced the efficacy of the COVID-19 vaccines and has, therefore, fuelled the pandemic situation.

Previous studies have reported that mRNA-based COVID-19 vaccines effectively elicit robust antibody and T cell responses, and protect individuals from SARS-CoV-2 infection. However, the incidence of breakthrough infections related to the Omicron variant and the waning of vaccine-induced neutralizing antibodies has led to the development of the COVID-19 booster vaccination strategy.

Several studies have reported the immediate benefits of COVID-19 booster immunizations, with respect to neutralization capacity against SARS-CoV-2 variants. However, there is a lack of data regarding the effect of the mRNA booster vaccine on the spike-specific CD8+ T cell response.

Additionally, not much evidence has been documented regarding the effectiveness of the three-dose vaccine regimes, their response to the breakthrough infection, and the duration of immune protection.

A new preprint study, posted on Research Square*,addressed the aforementioned gap in research and has longitudinally traced and profiled the CD8+ T cell responses after COVID-19 mRNA booster vaccination.

Scientists recruited thirty-eight individuals, from the Freiburg University Medical Center, Germany, who were immunized with the COVID-19 mRNA booster vaccine. They obtained blood samples from thirty-one individuals who received three doses of one of two mRNA vaccines, namely, BNT162b/Comirnaty or mRNA-1273/Spikevax vaccine.

Scientists reported that the study cohort included five participants who received four doses of the vaccine and were without a history of COVID-19 infection. Thirteen participants had a history of breakthrough infection after the third dose of a booster vaccination. All participants with breakthrough infection after booster vaccination exhibited mild symptoms without respiratory insufficiency.

In this study, the authors analyzed spike-specific CD8+ T cell responses, on a single epitope level, in participants who received COVID-19 mRNA-based booster vaccination (third and fourth) after four months of the third dose and one-two months post the fourth vaccination regime. The authors also evaluated spike-specific CD8+ T cell responses in breakthrough infections with the Omicron and Delta variants, post booster vaccination.

Researchers reported a fast and vigorous increase of spike-specific CD8+ T cell responses after third and fourth doses of the vaccine, with respect to breakthrough infection with the Delta and Omicron variants. Scientists reported that the magnitude and kinetics of immune response of this study cohort were similar to the spike-specific CD8+ T cell response after the second dose of the COVID-19 vaccine. This was observed by detecting a high level of expression and proliferation of CD38 and Ki-67. This finding strongly supports the rapid induction of functional CD8+ T cell responses after COVID-19 mRNA vaccination.

Scientists reported that the spike-specific CD8+ T cell booster responses after third and fourth doses of COVID-19 booster vaccination declined after around one to two months and, subsequently, reached a concentration similar to prior booster vaccination. This observation is extremely important and should be considered while formulating the booster vaccination strategy. Interestingly, in contrast to the steep waning off of the spike-specific CD8+ T cell boost response, a prolonged contraction after natural infection, irrespective of the infecting variant, has been observed.

A previous study reported the prolonged contraction of non-spike epitope-specific CD8+ T cells after COVID-19 infection. These differences in antigen half-life, antigen presentation, cytokines, innate immunity, and CD4+ T cell responses might be due to differences in responses after mRNA vaccination and COVID-19 infection. Therefore, there is a need for a better understanding of the interactions of immune components during natural infection and their responses post-vaccination.

In this study, researchers reported that the promising spike-specific CD8+ T cell memory response is not significantly affected by the third dose of vaccination. The current study revealed that the third dose did not augment long-term CD8+ T cell immunity and had no influence on the senescence of the CD8+ T cell memory pool. This finding is consistent with a previous study that reported antigen exposure does not cause T cell exhaustion of spike-specific CD8+ T cells. Researchers believe that the spike-specific CD8+ T cell booster response is an effector response that is based on a stable memory pool.

The authors revealed that mRNA booster vaccination is a powerful tool that can induce rapid and functional CD8+ T cell responses, which can be extremely beneficial to immediate alleviation of high viral burden. This strategy could effectively protect the vulnerable population and reduce the overwhelming burden of the healthcare system. However, the rapid decline in the spike-specific CD8+ T cell response hasto be considered while formulating the COVID-19 booster vaccination strategy.

Research Square publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

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Exploring short-term effectiveness of COVID-19 booster vaccine and stable CD8+ T cell memory after three doses - News-Medical.Net

A second line of defense the immune systems T cells may offer protection from COVID-19 even when vaccine-induced antibodies no longer can, according to new research out of the University of Wisconsin School of Veterinary Medicine.

The researchers discovered that a new, protein-based vaccine against the original version of the COVID-19 virus was able to teach mouse T cells how to recognize and kill cells infected with new, mutated versions of the virus. This T cell protection worked even when antibodies lost their ability to recognize and neutralize mutated SARS-CoV-2, the virus that causes COVID-19.

Marulasiddappa Suresh

Antibodies prevent COVID-19 infection, but if new variants escape these antibodies, T cells are there to provide a second line of protection, explains lead scientist Marulasiddappa Suresh, a professor of immunology and associate dean for research at the School of Veterinary Medicine.

The study, published in the Proceedings of the National Academy of Sciences on May 13, investigates the role of T cells, a specialized type of white blood cell, in defending against COVID-19 when antibodies fail.

When you receive a COVID-19 vaccine, your body learns to produce antibodies, proteins in the immune system that bind to and neutralize SARS-CoV-2. These antibodies circulate in the blood stream and protect you from illness by patrolling the nostrils, airways and lungs and wiping out the virus before it can cause infection or disease.

However, as SARS-CoV-2 mutates, these highly specific antibodies are less able to recognize new viral variants especially if the changes occur on the viruss spike protein, where the vaccines antibodies bind. This was especially apparent during the recent wave of the SARS-CoV-2 omicron variant, which has a staggering 37 mutations on its spike protein, making it more able to evade antibodies targeting the original viruss spike protein.

The biggest problem right now is that none of our current COVID-19 vaccines give complete protection against infection from emerging variants, especially the omicron sublineages BA.1 and BA.2, Suresh says.

Thats where T cells can help. Killer T cells aid the immune system by hunting and eliminating virus factories infected cells, says Suresh. So, when antibodies cannot neutralize the virus prior to infection, T cells can clear it quickly, causing mild or no noticeable symptoms.

With this information in hand, the UWMadison research team, co-led by Suresh and professor of pathobiological sciences Jorge Osorio and assisted by scientist Brock Kingstad-Bakke and doctoral student Woojong Lee, explored how T cells and antibodies can work to prevent COVID-19 infection altogether.

Brock Kingstad-Bakke, a scientist in the UW School of Veterinary Medicine. Photo courtesy of the School of Veterinary Medicine

The researchers developed an experimental protein-based vaccine containing the unmutated version of the spike protein from the original SARS-CoV-2 virus. This vaccine was also designed to elicit a strong T cell response to the viral spike protein, allowing the lab to test the extent to which T cells can protect against COVID-19 infection in the presence and absence of virus neutralizing antibodies.

After injecting mice models with their vaccine, researchers then exposed them to two SARS-CoV-2 variants and tested their susceptibility to infection under different conditions.

While vaccine-stimulated antibodies were unable to neutralize the mutated SARS-CoV-2 variants, mice were still immune to COVID-19 caused by the mutated viruses, due to action by T cells that were induced by the vaccine.

Unlike antibodies, T cells are able to detect unfamiliar strains of virus because the viral fragment that they recognize does not change considerably from one variant to the next.

This work has important implications for future T cell-based vaccines that could provide broad protection against emerging SARS-CoV-2 variants. The experimental vaccine is protein-based and designed to evoke a strong T cell response, differentiating it from currently available mRNA vaccines.

Now, the Suresh lab is studying how exactly T cells defend against SARS-CoV-2 and whether commercially available COVID-19 vaccines may induce these same mechanisms of T cell immunity to protect against emerging variants when the virus dodges established antibodies.

I see the next generation of vaccines being able to provide immunity to current and future COVID-19 variants by stimulating both broadly-neutralizing antibodies and T cell immunity, Suresh says.

This work was supported in part by the National Institutes of Health (grants U01 AI124299, R21 AI149793-01A1).

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Experimental COVID-19 vaccine provides mutation-resistant T cell protection in mice - University of Wisconsin-Madison

People diagnosed with cancer whove received a COVID-19 vaccine have a higher risk of a breakthrough COVID infection than vaccinated people without cancer, according to a study.

The research was published online on April 8, 2022, by the journal JAMA Oncology. Read Breakthrough SARS-CoV-2 Infections, Hospitalizations, and Mortality in Vaccinated Patients With Cancer in the US Between December 2020 and November 2021.

COVID-19 vaccine recommendations are different for people with weakened immune systems (called immunocompromised). Several breast cancer treatments including chemotherapy, certain targeted therapies, and immunotherapy can weaken your immune system. People with moderately to severely compromised immune systems are especially vulnerable to COVID-19, and may not build the same level of immunity to the virus after being fully vaccinated as people who are not immunocompromised.

If youre currently receiving breast cancer treatment, its a good idea to ask your doctor if you should follow these recommendations from the Centers for Disease Control and Prevention (CDC) for moderately to severely immunocompromised people:

If your initial vaccine was Pfizer or Moderna, the CDC recommends you get a third dose of the same vaccine you received initially at least 28 days after your second dose.

After the third dose of either the Pfizer or Moderna vaccine, you should receive a booster dose of either of the two mRNA vaccines at least three months after your third dose.

If your initial vaccine was J&J, the CDC recommends you get a second dose of either the Pfizer or Moderna vaccine at least 28 days after receiving the vaccine. The CDC also recommends a booster dose of either the Pfizer or Moderna vaccine at least two months after your second dose. The FDA has limited emergency use authorization to people ages 18 and older who have had a severe allergy to an mRNA vaccine, are unable to get an mRNA vaccine because these arent available, or strongly prefer the J&J vaccine.

The U.S. Food and Drug Administration (FDA) granted emergency use authorization to Evusheld (chemical name: tixagevimab combined with cilgavimab), an antibody therapy used to prevent COVID-19 in people age 12 and older who have moderately to severely compromised immune systems or cannot get a COVID-19 vaccine because of a severe allergic reaction to its ingredients. Evusheld works differently from a vaccine, and may be an option for immunocompromised people who may not develop enough immunity after a COVID-19 vaccine.

Even though being vaccinated helps protect you from serious illness, its still possible to get whats called a breakthrough COVID-19 infection. People diagnosed with cancer may have lower COVID-19 antibody levels after being vaccinated. The researchers wanted to know how many people in the United States diagnosed with cancer whod received a COVID-19 vaccine had a breakthrough infection. The researchers also wanted to see the outcomes of these breakthrough infections.

For this study, the researchers looked at the records of 45,253 people who had been diagnosed with at least one of 12 types of cancer and 591,212 people who had not been diagnosed with cancer. All the people had received a COVID-19 vaccine between December 2020 and November 2021 and hadnt been diagnosed with COVID-19 before being vaccinated. The records came from 66 healthcare organizations from all 50 states.

People diagnosed with cancer were older and more likely than people without cancer to have other health problems.

Breast cancer was the most common cancer among people in the study:

13,032 were diagnosed with breast cancer

11,421 were diagnosed with prostate cancer

6,962 were diagnosed with hematologic cancer, including leukemia, lymphoma, and multiple myeloma

3,094 were diagnosed with colorectal cancer

2,926 were diagnosed with skin cancer

2,849 were diagnosed with lung cancer

9,833 were diagnosed with bladder, endometrial, kidney, liver, pancreatic, or thyroid cancer

These numbers total more than 45,253 because some people were diagnosed with more than one type of cancer.

The researchers measured the monthly rate of breakthrough COVID-19 infection as the number of new cases in every 1,000 people. The rate was higher in people with cancer than in people without cancer:

From February to March 2021, the rate was 19.6 in people with cancer versus 4.9 in people without cancer.

From April to May 2021, the rate was 43.1 in people with cancer versus 13.8 in people without cancer.

From June to July 2021, the rate was 30.6 in people with cancer versus 17.4 in people without cancer.

From August to September, the rate was 51.7 in people with cancer versus 41.3 in people without cancer.

From October to November 2021, the rate was 52.1 in people with cancer versus 46.9 in people without cancer.

The rate differences were statistically significant, which means they were likely because of the cancer diagnosis and not just due to chance.

Among the people diagnosed with cancer, the risk of a breakthrough infection was 13.6% during the study period. The risk among people not diagnosed with cancer was 4.9%.

People diagnosed with pancreatic cancer had the highest risk, and people diagnosed with thyroid cancer had the lowest risk. Breakthrough infection risk was:

24.7% for people diagnosed with pancreatic cancer

22.8% for people diagnosed with liver cancer

20.4% for people diagnosed with lung cancer

17.5% for people diagnosed with colorectal cancer

17.4% for people diagnosed with bladder cancer

16.0% for people diagnosed with kidney cancer

14.9% for people diagnosed with hematologic cancer

12.5% for people diagnosed with skin cancer

12.8% for people diagnosed with prostate cancer

11.9% for people diagnosed with endometrial cancer

11.9% for people diagnosed with breast cancer

10.3% for people diagnosed with thyroid cancer

Among the people diagnosed with cancer, people who visited a doctor because of certain cancers between November 2020 and November 2021 had a higher risk of a breakthrough infection than people who didnt visit a doctor because of cancer. This finding suggests that people who were actively being treated for certain cancers had a higher risk of a breakthrough infection than people whod completed treatment. Higher risk was seen in people diagnosed with:

breast cancer

hematologic cancer

colorectal cancer

bladder cancer

pancreatic cancer

The researchers then matched people with and without cancer on the basis of:

age, ethnicity, and other demographics

vaccine type

other medical conditions

People with cancer still had a higher risk of breakthrough infection than people without cancer.

The researchers also compared breakthrough infection outcomes in people with and without cancer:

The risk of hospitalization was 31.6% in people diagnosed with cancer and 25.9% in people without cancer.

The risk of dying was 6.7% in people diagnosed with cancer and 2.7% in people without cancer.

These results emphasize the need for patients with cancer to maintain mitigation practice, especially with the emergence of different virus variants and the waning immunity of vaccines, the researchers wrote.

This studys results are concerning for people whove been diagnosed with cancer especially for people who are actively receiving breast cancer treatment.

Other research strongly suggests that people diagnosed with cancer have a higher risk of getting COVID-19 than people who have not been diagnosed with cancer. This risk is higher for people who have been recently diagnosed with cancer.

But knowing you have a higher risk of getting a COVID-19 breakthrough infection and having serious complications and worse outcomes can be motivation to stay vigilant about your safety. This awareness also can encourage you to keep following COVID-19 precautions, even if the rest of the world isnt. Its extremely important that you:

practice physical distancing

wear a face mask that fits snugly when you go out of the house

wash your hands frequently and use hand sanitizer when you cant wash your hands

avoid crowds and poorly ventilated spaces

clean and disinfect surfaces you touch frequently, including doorknobs, light switches, phones, keyboards, handles, and faucets

be alert for any COVID-19 symptoms, including loss of smell or taste, as well as fever, cough, and shortness of breath

talk to your doctor about COVID-19 vaccines and boosters, and get fully vaccinated as soon as you can if its recommended for you

Learn more about Coronavirus (COVID-19): What People With Breast Cancer Need to Know.

To talk with others about COVID-19 and breast cancer, join the conversation on All things COVID-19 or coronavirus in our community.

Written by: Jamie DePolo, senior editor

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Vaccinated People Diagnosed With Cancer Have Higher Risk of Breakthrough COVID-19 Infection - Breastcancer.org

Ledge Light Health District has scheduled free COVID-19 vaccination clinics at senior centers in New London, East Lyme and Groton.

Only the Moderna vaccine will be available for people 18or older who need a first or second dose or are eligible for a first or second booster dose.

The clinics are from noon to 2 p.m. Friday at the New London Senior Center, corner of Brainard and Mercer streets; from 2 to 4 p.m. Monday, May 23 at the East Lyme Senior Center, 37 Society Road, Niantic; and from 1 to 3 p.m. Tuesday, June 7 at the Groton Senior Center, 102 Newtown Road.

Those eligible for a first booster shot include those 18or older who completed a primary series of either the Moderna or Pfizer vaccineat least five months ago, or those 18 or older who had a primary dose of the Janssen (Johnson & Johnson) vaccine at least two months ago.

People50 or older who received a first booster dose of any COVID-19 vaccine at least four months ago are eligible for a second booster shot.

No appointment, insurance or ID is necessary at the clinics. People should bring their CDC vaccination card, if they have one.

The CDC recommends that everyone 5 and older get a primary series of COVID-19 vaccine and that everyone 12 and older also receive a booster. For a complete list of community clinics, including those where vaccinations are available for people younger than 18, visit llhd.org.

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Ledge Light offering COVID-19 vaccination clinics at senior centers in New London, East Lyme, Groton - theday.com

(Precision Vaccinations)

Vaccine research organizations recently announced a new program in Kenya, Rwanda, and the Democratic Republic of Congo to evaluate the safety and immunogenicity of homologous and heterologous COVID-19 vaccine booster regimens in people living with Human immunodeficiency virus (HIV).

The Coalition for Epidemic Preparedness Innovations (CEPI) and the Kenya-based Victoria Biomedical Research Institute (VIBRI) confirmed on May 11, 2022, that about $12.5 million in funding would be deployed to assess this mix and match booster approach in HIV populations.

This vital research is needed since 38 million people globally live with HIV, and two-thirds of them arein sub-Saharan Africa.

Data on the effectiveness of COVID-19 vaccines in people living with HIV are limited, and many outstanding questions remain, such as:

Dr. Melanie Saville, Executive Director of Vaccine R&D, CEPI, commented in a related media release, To effectively expand access to COVID-19 vaccines around the world, we urgently need to boost clinical research into how well these vaccines work in vulnerable populations, especially in people living with HIV.

For example, people living with HIV could have reduced immune responses to COVID-19 vaccination, increasing the chances of breakthrough infections.

This study will help to gather the data needed to fill this gap in our understanding and inform how governments and COVAX can optimize their vaccination strategies going forwards to better protect this large vulnerable population of people who are potentially immunocompromised.

Participants in this Phase 2B study who have already received homologous COVID-19 vaccination with either Moderna or Pfizer mRNA vaccines or the vaccines produced by Janssen, Sinovac, or Sinopharm will receive a booster of either the Janssen or Novavax vaccines five to seven months after completion of the primary vaccination series.

Each study participantaged 12 to 64 years living with or without HIV infectionwill be followed over an 18-month period. After booster vaccination, investigators will assess the safety and immune response at months 6, 12, and 18.

CEPI is an innovative partnership between public, private, philanthropic, and civil organizations

This is the latest program to be funded in response to a CEPI Call for Proposals launched in January 2021, which aims to address current gaps in our clinical knowledge of vaccine performance both now and in the long term.

Regarding HIV vaccine development, the U.S. National Institute of Allergy and Infectious Diseases (NIAID) recently launched a Phase 1 clinical trial evaluating three experimental HIV vaccines"Finding an HIV vaccine has proven a daunting scientific challenge," commented Anthony S. Fauci, M.D. NIAID director, on March 14, 2022.

"With the success of safe and highly effective COVID-19 vaccines, we have an exciting opportunity to learn whether mRNA technology can achieve similar results against HIV infection."

More information about the HVTN 302 study is available on ClinicalTrials.gov using the identifier NCT05217641.

Additional HIV vaccine development news is posted at PrecisionVaccinations.com/HIV.

PrecisionVaccinations publishes fact-checked research-based vaccine news.

Link:

Do HIV and COVID-19 Vaccines Mix? - Precision Vaccinations

Nuvaxovid is a protein-based vaccine engineered from the genetic sequence of the first strain of SARS-CoV-2, the virus that causes COVID-19.

The vaccine was found to be about 90 per cent effective at preventing symptomatic COVID-19 and 100 per cent effective in preventing severe infection in trials.

As of May 12, 92 per cent of Singapores population have completed their primary vaccination series, while 75 per cent have received their booster doses.

With good vaccination coverage and the majority of our total population well-protected, we will be progressively stepping down the number of vaccination centres from end-May 2022, as previously announced on Apr 22, said MOH.

The first tranche of five Joint Testing and Vaccination Centres will open on May 24, as part of efforts to ensure that COVID-19 testing and vaccination services remain accessible to the general public, it added.

"These centres are designed with the ability to scale up operations in the event of an emerging variant of concern in future."

Another five centres will open progressively across the island from end-June.

To enable the medical service providers to better manage vaccine preparation and reduce any unnecessary wastage, the public is strongly encouraged to book an appointment via the National Appointment System before proceeding to the JTVCs, said MOH.

The centres are as follows:

See original here:

Appointment bookings to receive Nuvaxovid COVID-19 vaccine open: MOH - CNA

In advance of the second Global COVID-19 Summit, co-hosted by the United States, Belize, Germany, Indonesia, and Senegal, the following statement is attributable to Michele Heisler, MD, MPA, medical director at Physicians for Human Rights (PHR) and professor of public health and internal medicine at University of Michigan:

"As the world surpasses 15 million deaths associated with COVID-19, the gathering of governments, companies, and philanthropies at the second Global COVID-19 Summit is urgently needed.

"However, it is both shameful and imprudent that the United States is coming to this summit with no additional funds committed to support the global COVID-19 vaccine roll out.

"New and emerging variants imperil progress against the pandemic. Thousands of people still die each day. COVID-19 continues to roil health systems and societies. It is thus shortsighted and a failure of leadership for the United States, with all its economic and technological might, to not bring new commitments to the global fight against COVID-19.

*"To protect people in the United States and around the world, Congress must immediately pass a robust global pandemic response package that prioritizes global vaccine distribution and equity. It is essential that U.S. global COVID-19 aid not be tied to unrelated issues, particularly not to draconian Title 42 border expulsions, which is an immigration control order masquerading as pandemic policy."*

"In the United States, nearly 1 million confirmed COVID-19 deaths are both an unfathomable tragedy and a stark reminder of the consequences of underinvestment in global health and pandemic responses. World leaders should ensure that everyone everywhere has access to high-quality COVID-19 vaccines, treatments, diagnostics, and necessary supports such as oxygen.

"In light of the massive public spending on COVID-19 vaccine research and development, we also call on the United States government to push pharmaceutical corporations to waive intellectual property restrictions, share technological know-how, and help boost global vaccine production and distribution capacity.

"Largely due to the hoarding of vaccine supplies by high-income countries and the pharmaceutical companies' refusal to advance a 'people's vaccine,' the world will likely fall far short of the 70 percent global vaccination coverage goal embraced by the World Health Organization and the U.S. government. Physicians for Human Rights calls on governments and organizations attending the Global COVID-19 Summit to double down on their efforts to achieve this critical target, while also prioritizing vaccine distribution to health workers, marginalized groups, and others most at risk of severe health consequences from COVID-19.

"More than two years into the pandemic and more than a year after COVID-19 vaccines became widely available, world leaders have no excuse for the continued staggering inequities and stalled progress in global vaccination efforts."

Physicians for Human Rights (PHR) is a New York-based advocacy organization that uses science and medicine to prevent mass atrocities and severe human rights violations. Learn more here.

Media Contact

Kevin Short

Media Strategy, Senior Manager media@phr.org1.917.679.0110

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Shortsighted and a Failure of Leadership: Congress and White House Must Act on Global COVID-19 Response and Vaccine Equity: PHR - World - ReliefWeb

CNN

With waning immunity and a coronavirus that seems to become more infectious with each new variant, the Biden administration predicts that up to 100 million more people could get Covid-19 in the fall and winter. That estimate makes it crucial that as many people as possible get booster shots of Covid-19 vaccine, experts say. And if youre eligible, its a good time to get a second booster.

Less than half of eligible Americans only about a third of the total US population have gotten a first booster dose, according to the US Centers for Disease Control and Prevention. Only about 10 million people have received a second booster, which is authorized for people 50 and older, along with those who are 12 and older who are moderately to severely immunocompromised.

The CDC encourages people to be up-to-date on Covid-19 vaccinations which includes getting boosters at the appropriate time but still defines a person to be fully vaccinated if theyve received at least their initial vaccination series.

But this week, a senior Biden administration official was more direct: All adults need a third shot.

Vaccination is the best way for individuals to protect themselves against Covid-19, and protection is most effective with at least three shots, the official said.

Getting more Americans boosted against Covid-19 could make a big difference as far as case numbers go, according to Dr. Peter Marks, director of the Center for Biologics Evaluation and Research at the US Food and Drug Administration. He told the American Medical Association on Monday that he is a little concerned about where the Covid-19 pandemic is heading.

Its really important that we try to get the half or a little bit more than a half of Americans who have only received two doses to get that third dose, Marks said. That may make a difference moving forward here, and it may particularly make a difference now that were coming into yet another wave of Covid-19.

The current rising Covid cases are nothing like what the US saw with the initial Omicron surge, but as of Monday, the US is averaging 71,577 new cases a day, according to Johns Hopkins University.

Case rates are currently highest in the Northeast region of the US, where booster uptake is best. Nearly half of Vermonts population is fully vaccinated and boosted, along with more than 40% of the population in Maine, Rhode Island, Connecticut and Massachusetts, according to CDC data.

But cases are also starting to tick up in the South, where less than a quarter of the population is fully vaccinated and boosted. In North Carolina, Alabama and Mississippi, less than 1 in 5 people have received their booster shot.

Everyone in the US who is 12 and older is eligible for a booster dose. Only the Pfizer/BioNTech vaccine is available as a booster for adolescents 12 to 17.

Adults who were initially vaccinated with the mRNA vaccine are eligible for a booster dose five months after the initial series. Those vaccinated with Johnson & Johnson are eligible for a booster dose two months after their first shot.

CDC data shows that booster uptake is higher in older age groups in the US, consistent with broader vaccination trends. But nearly 2 out of 5 seniors age 65 and older and more than 3 out of 5 adults overall do not have either of their booster shots.

People who get three doses of an mRNA vaccine have a relatively low rate of Covid-related urgent care visits and hospitalizations compared with those who got only two doses, studies have shown. Even with the more infectious Omicron variant, a booster seems to protect against more severe disease.

Scientists are still trying to determine whether younger age groups would benefit from an additional vaccine dose. Pfizer and BioNTech have requested emergency use authorization for the 5-to-11 age range.

That will hopefully be acted on in the not-too-distant future, Marks said.

A fourth dose of Moderna or Pfizer/BioNTechs mRNA Covid-19 vaccine which is already authorized for people 50 and older in the United States seems safe and provides a substantial boost to immunity at similar or even better levels than a third dose, according to a study published Monday.

The researchers gave study participants whose median age was 70.1 years a half dose of the Moderna vaccine or a full dose of the Pfizer vaccine in a random selection in January, about seven months after they received their first booster. The second booster didnt seem to have any major side effects. The biggest complaints were arm pain and fatigue.

The booster also generated an immune response at day 14 that was higher than that at day 28 after the third dose of the Pfizer or Moderna Covid-19 vaccine.

When the researchers compared the mRNA vaccines, Modernas fourth dose seemed to do slightly better than Pfizers, but its unclear why. Both generated what scientists considered a significant fold change in protective antibodies. T-cell responses were also boosted after the fourth dose.

Antibodies are a first line of immune protection that can stop a virus from infecting cells. T-cells come in later and destroy infected cells. T-cells cant protect against mild infections, but they can keep infections from progressing to severe disease.

Fourth-dose Covid-19 mRNA booster vaccines are well tolerated and boost cellular and humoral immunity, the study says. Peak responses after the fourth dose were similar to, and possibly better than, peak responses after the third dose.

The study also showed that some people who had higher levels of antibodies before the fourth dose of the Covid-19 vaccine had only limited boosting. Those with a history of Covid-19 infection had a similar limited response. The authors say this suggests that there may be a ceiling or maximum response that can come with a fourth vaccine dose.

The study didnt look specifically at neutralization of the Omicron variant.

Two earlier studies out of Israel showed that hospitalization and death rates from Covid-19 could be reduced with a fourth vaccine dose given at least four months after the third dose. The reduction in hospitalizations and death persisted over time with this fourth shot.

Marks hopes that the next generation of Covid-19 vaccines which he predicts will come in the next year or two will be even better at protecting people against the whole variety of Covid variants and provide a more robust immune response.

The FDAs vaccine advisory committee will meet in late June to review the data on vaccines, including monovalent (which would target a single variant) and bivalent vaccines (which could target the original strain of the virus plus another).

Its a little bit of a challenge here because we dont know how much further the virus will evolve over the next few months, Marks said. But we have no choice, because if we want to produce the hundreds of millions of doses that need to be available for a booster campaign, we have to start in the early July timeframe or even sooner to get those kinds of numbers.

The FDA committee may also discuss whether an additional booster should be recommended in the fall for the general population or for target groups, Marks said.

Some doctors have said theyve heard from patients who want to wait to get a booster to get better coverage for winter. Marks said that waiting to get a booster is a bad idea, especially if those people havent had Covid-19 recently.

Why? Because its going to be four or five, six months before we get to when you get your next booster, he said. Youre talking about having several months there at risk.

Even with a fall and winter surge predicted, cases are on the increase now, and those who have had only two mRNA shots are vulnerable.

Rather than just being casual about it, Marks said. I would urge them to try to get that third dose to ramp up the immunity just because we do have plenty of circulating Covid-19.

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Why Covid-19 vaccine boosters may be more important than ever - CNN