REHOBOTH BEACH, Del. PresidentJoe Bidendid not wear a face mask in public a couple of times after the White Houseannounced he had tested positive for COVID-19.The White House said the Democratic incumbent was experiencing mild symptoms while the presidents physician said Biden would self-isolate in accordance with CDC guidance for symptomatic individuals.
What does the CDC guidance say? What does the White House say?
After the announcement on Wednesday, Biden emerged bare-faced from the motorcade after he arrived at the airport in Las Vegas, where he had made several appearances, and boarded Air Force One. He also was not wearing a mask, which medicals professionals have said can help slow the spread of disease, as he stepped off the plane hours later at Dover Air Force Base in Delaware. Biden was surrounded by Secret Service agents and aides on both ends of the trip.
White House press secretary Karine Jean-Pierre said inWednesdays announcementthat Biden, 81, was experiencing mild symptoms and would stick to prearranged plans to travel to his home in Rehoboth Beach, where he would isolate.
Bidens physician, Dr. Kevin OConnor, said in a separate statement that Biden had a runny nose, dry cough and a feeling of general malaise. He said Biden was being treated with the drug Paxlovid and will be self-isolating in accordance with CDC guidance for symptomatic individuals.
TheCenters for Disease Control and Prevention encourages peoplerecovering from COVID-19 or any other respiratory illness to wear masks as part of an overall strategy to reduce transmission, but masks are not mandated.
The CDC recommends that people stay home and away from others if theyre feeling sick. They say people can resume normal activities when symptoms have started to improve and the person no longer has a fever.
The CDC describes masks as an additional strategy for preventing disease spread, but it generally leaves it up to individuals to decide whether to use them. It calls masks especially helpful when someone is sick and suggests they be used as a precaution during recovery.
The White House has not responded to an emailed request for comment about why Biden chose not to wear a mask.
OConnor said Thursdaythat Biden is still experiencing mild upper respiratory symptoms from COVID-19,. The president does not have a fever and his vital signs remained normal. Hes being treated with the drug Paxlovid.
Quentin Fulks, the principal deputy manager of Bidens reelection campaign, said Thursday that Biden was feeling fine and was making calls and doing work. Fulks spoke at a news conference on the sidelines of the Republican National Convention in Milwaukee.
White House national security spokesperson John Kirby told reporters during a separate Zoom briefing that Biden was being kept up to speed as appropriate by his leadership team, and certainly that includes on the national security front.
The Associated Press
The Associated Press
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The White House confirmed Wednesday that President Biden has tested positive for COVID and is experiencing mild symptoms.
WASHINGTON - President Joe Biden has tested negative for COVID-19, the White House said in a statement.
"The President's symptoms have resolved," Dr. Kevin O'Connor, the president's physician, wrote in a statement. "Over the course of his infection, he never manifested a fever, and his vital signs remained normal, to include pulse oximetry. His lungs remained clear."
"He will continue to be monitored for any recurrence of illness. The President continues to perform all of his presidential duties," the statement continued.
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Last Week, the president tested positive for COVID while campaigning in Las Vegas. He had to cancel a speech at the UnidosUS annual conference before isolating himself at his home in Delaware.
RELATED: Biden tests positive for COVID-19 with mild symptoms, will self isolate
O'Connor had said in a note that Biden "presented this afternoon with upper respiratory symptoms, to include rhinorhea (runny nose) and non-productive cough, with general malaise." After the positive COVID-19 test, Biden was prescribed the antiviral drug Paxlovid and has taken his first dose, O'Connor said.
Biden tested positive for COVID-19 in July 2022 and a second time slightly more than three days after he was cleared to exit coronavirus isolation. The second incident was a rare case of "rebound" infection following treatment with an anti-viral drug.
RELATED: Long COVID is more prevalent in these states, CDC data shows
Biden received the updated COVID-19 vaccine and annual flu shot, the White House said last September.
According to the Centers for Disease Control and Prevention, there have been upticks in emergency room visits and hospitalizations from COVID-19. There has also been a pronounced increase in positive test results in much of the country particularly the southwestern U.S.
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Axios reporter Victoria Knight joins LiveNOW's Andy Mac with more insight after Dr. Anthony Fauci was grilled by lawmakers on Capitol Hill this week over COVID origins.
Given that the pandemic was declared officially over as of May 5, 2023, public health officials dont collect the same amount of COVID data as they once did.
Since COVID-19 emerged in 2020, scientists have learned that the virus has seasonal patterns, Varma said, with predictable peaks in spring/early summer and winter.
RELATED: Experts worry over pandemic's toll on child development
"Winter peaks are easy to explain more people spend time indoors, and there are changes in the climate, including relative humidity, that make it easier for infections to spread through the air," Varma, who served as the New York City mayor's senior adviser for public health during the COVID-19 pandemic, told Fox News Digital.
Its not quite as easy, however, to explain the peak during warmer weather.
"It may be because the virus evolves at a frequency that aligns with the spring/summer or there could be other environmental factors that we do not understand well," Varma said.
As of June 27, the CDC recommends that all people 6 months of age and older get updated 2024-2025 COVID vaccines when they become available in fall 2024.
The updated vaccine will target the new, prevalent subvariants.
FOX News and The Associated Press contributed to this report. This story was reported from Los Angeles.
President Joe Biden tested positive for COVID-19 last week. Dr. Kevin OConnor, Bidens physician, said the president contracted the KP.2.3 variant. It marks the third time Biden has contracted the virus even though he has received numerous vaccines and boosters. The fact that he repeatedly contracted the virus despite his multiple inoculations would be the latest example of the efficacy of the vaccines being oversold to the public.
However, what does Bidens latest COVID-19 diagnosis say about the efficacy of vaccinations and boosters?
The hostility over vaccines in the countrys political discourse has long subsided. But flashback to when Biden and Democrats were pressuring people to get the vaccines and claiming that doing so would prevent someone from contracting the disease or spreading it to another person. Recall that during a town hall in July 2021, Biden said, Youre not going to get COVID if you have these vaccinations. Bidens statement was debunked long ago and is an example of one of the numerous lies he made during his time in office.
Another example was when Rochelle Walensky, the then-director of the Centers for Disease Control and Prevention, said in March 2021 during an interview on MSNBC, that vaccinated people dont carry the virus and dont get sick. Again, this was also debunked a long time ago, and it has since been established that the vaccines do offer some protection against contracting the virus but far from the initial projections many of the nations leaders and experts suggested.
But with Biden getting COVID-19 three times in the last two years and with the White House clarifying that he was up to date on his vaccinations, or boosted, it raises some questions on the vaccines and boosters. Getting COVID-19 at a rate greater than once per year does not inspire a lot of confidence for the public to continue to get vaccinated with hopes of being immune to the virus.
However, it should also suggest, based on a recent study, that the expectations of being vaccinated and boosted should seemingly shift from acting as an impenetrable wall of sorts that protects people from getting or spreading the virus to the vaccines preventing people from experiencing lingering harmful health problems, such as long COVID, or at least lessening the severity of the symptoms.
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For example, a recent study in the New England Journal of Medicine revealed there was a 70% drop in long COVID cases due to vaccination. So there is an argument to be made that vaccines are beneficial, but that argument is not predicated on the thought that getting the vaccine will prevent someone from contracting the virus altogether which is what was originally said. Unfortunately, this perception still dominates many of the peoples views on the efficacy of vaccines. It would probably help if there were more public statements on how the perception of the benefits of vaccines should be shifted to focus on preventing long-term negative health problems.
However, given that the experts and leaders were, shall we say, less than candid at the height of the pandemic, it would be hard to imagine vaccine detractors believing anything. And having the president get COVID-19 three times in two years does little to remove such skepticism.
COVID-19 blue and green vector typography banner with virus symbol
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During the June 3, 2024, House Oversight Committee regarding the Coronavirus Pandemic, the 6-foot rule was again thrown into the spotlight, and questions about its appropriateness and effectiveness were raised. One of the Representatives questioned the continuation of advocating for 6 feet of social distancing after it was known the virus was aerosolized. This question exemplifies one of the underlying problems in our pandemic responsedividing the spread of respiratory pathogens into aerosols and large droplets.
Some critics of the 6-foot rule have pointed to the adverse impacts of social distancing on schools and businesses. However, social distancing was adopted by almost every industrialized nation, even Sweden. In most countries, including South Korea, Australia, Belgium, Germany, Greece, Italy, Netherlands, Portugal, and Spain, a social distance of 1.5 yards or meters was recommended. The US, Canada, and the UK chose 2 yards or meters. A few countries chose 1 meter of separation, but this is so close that accidental contact between individuals can occur.
Social distancing has been advocated by science dating back to the 1800s and most recently has been supported by the findings published in the Lancet by Chu and colleagues. They observed a strong association between the proximity of the exposed individual with the risk of infection. There was a 12.8% chance of transmission for distances less than 1 meter, which dropped to 2.6% for distances greater than 1 meter. The authors stated, We found evidence of moderate certainty that current policies of at least 1-meter physical distancing are probably associated with a large reduction in infection and that distances of 2 meters might be more effective, as implemented in some countries. The researchers recommended implementing at least 1 meter of physical distancing and, if possible, 2 meters to mitigate the transmission of SARS-CoV-2 (the virus that causes COVID-19).
There is ample evidence that the 6-foot rule will help decrease spread, but with a highly infectious virus, it alone will not provide adequate protection. Here is why:
Most importantly, droplets are a type of medium similar to solid particles (particulate matter or PM) that can spread the virus. Both droplets and particles have a continuum of sizes, not just large ones and small ones. Particles up to 100 microns can aerosolize. Breathing, talking, and singing can aerosolize particles. Smaller particles are generated deep in the lower airway, with larger particles in the upper airway. Breathing produces particle sizes below 0.8 microns, and speech produces additional particles up to 5 microns in size. The vast majority of the particles are less than 10 microns. Particles less than 1 micron have been observed to contain more SARS-CoV-2 viruses than larger particles.
Respiratory droplet aerosols can be highly infectious, decreasing their infectivity by approximately 10% every 20 minutes. However, the virus's survivability varies with relative humidity, and lower values decrease viral stability.
Air pollution from fuel combustion, such as car exhaust, produces fine particles (PM2.5) that can facilitate the spread of SARS-CoV-2 (the virus that causes COVID-19). Individuals living in regions with high PM2.5 levels are known to have higher COVID-19 death rates. As with small aerosols caused by droplets, these particles aerosolize and can spread much further than 6 feet.
Although the 6-foot rule will protect against large nonaerosolized particles, it will not afford the needed protection if one is exposed to a highly infectious airborne virus that spreads through the air. Because aerosols float in the air, ventilation is a key factor in their elimination. In highly ventilated indoor settings or outdoor venues, aerosolized particles will dissipate, but large particles will not. Thus, the 6-foot rule adds substantial protection if you do not have a mask and are outdoors. In highly ventilated indoor settings, the same may be true. This is why a CO2 monitor is handy for measuring indoor ventilation. However, the safest option indoors or in crowded outdoor settings is wearing an N95 mask.
The answer regarding whether the 6-foot rule is effective is yes. But it makes sense and is appropriate only if indoor ventilation is also addressed. Not having safe indoor ventilation is one of the most significant failings of our pandemic response.
References
US Congress. Committee on Oversight and Accountability. A Hearing with Dr. Anthony Fauci. 2154 Rayburn House Office Building. June 3, 2024. Accessed July 21, 2024. https://oversight.house.gov/hearing/a-hearing-with-dr-anthony-fauci/
Daily Mail. Rep. Comer says he 'likes the idea' of Fauci being arrested. MSN.com. June 2020. Accessed July 21, 2024. https://www.msn.com/en-us/news/politics/top-gop-says-he-likes-the-idea-of-fauci-being-arrested/ss-BB1nGvwA.
Shukman D. Coronavirus: Could social distancing of less than two metres work? BBC. June 32, 2020. Accessed July 21, 2024. https://www.bbc.com/news/science-environment-52522460.
Sweden hardens COVID curbs amid worries over Omicron. Reuters. Dec. 21, 2021. Accessed July 21, 2024. https://www.reuters.com/world/europe/sweden-tightens-covid-restrictions-cases-mount-2021-12-21/.
Eldred SM. Coronavirus FAQ: How Do The Rules of 6 Feet And 15 Minutes Apply To The Delta Variant? NPR. Aug. 27, 2021. Accessed July 21, 2024. https://www.npr.org/sections/goatsandsoda/2021/08/27/1031753581/coronavirus-faq-how-does-the-6-feet-15-minutes-rule-apply-to-the-delta-variant.
Chu DK, Akl EA, Duda S, et al; COVID-19 Systematic Urgent Review Group Effort (SURGE) study authors. Physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2 and COVID-19: a systematic review and meta-analysis. Lancet. 2020;395(10242):1973-1987. doi:10.1016/S0140-6736(20)31142-9. https://pubmed.ncbi.nlm.nih.gov/32497510/.
Harvard T.H. Chan School of Public Health. Air pollution linked with higher COVID-19 death rates. Accessed July 21, 2024. https://www.hsph.harvard.edu/news/hsph-in-the-news/air-pollution-linked-with-higher-covid-19-death-rates/.
Lam V. Air pollution can increase the risk of COVID infection and severe disease a roundup of what we know. The Conversation. Accessed July 21, 2024. https://theconversation.com/air-pollution-can-increase-the-risk-of-covid-infection-and-severe-disease-a-roundup-of-what-we-know-201813.
Oswin HP, Haddrell AE, Otero-Fernandez M, et al. The dynamics of SARS-CoV-2 infectivity with changes in aerosol microenvironment. Proc Natl Acad Sci U S A. 2022;119(27). doi:10.1073/pnas.2200109119. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9271203/.
Morawska L. Health Watch USA Conference. Sept. 14, 2022.Accessed July 21, 2024. https://www.healthwatchusa.org/conference2022/2022Conference_downloads/05-Morawska-20220914-Webinar.pdf.
Morawska L, Johnson GR, Ristovski ZD, et al. Size distribution and sites of origin of droplets expelled during expiratory activities. J Aerosol Sci. 2009;40(3):256-269. doi:10.1016/j.jaerosci.2008.11.002. https://www.sciencedirect.com/science/article/abs/pii/S0021850208002036.
Santarpia JL, Herrera VL, Rivera DN, et al. The Infectious Nature of Patient-Generated SARS-CoV-2 Aerosol. medRxiv. July 21, 2020. Accessed July 21, 2024. doi:10.1101/2020.07.13.20041632. https://www.medrxiv.org/content/10.1101/2020.07.13.20041632v2.
Fox M. Six-foot social distancing rule misses bigger risks, MIT experts say. CNN. April 27, 2021. Accessed July 21, 2024. https://www.cnn.com/2021/04/27/health/covid-spread-inside-wellness/index.html.
LAS VEGAS President Biden has tested positive for the coronavirus and is experiencing mild symptoms, including a cough, runny nose and general malaise, the White House said Wednesday.
Biden has canceled his planned events in Las Vegas and has departed en route to Delaware. He plans to isolate there while continuing to work, White House press secretary Karine Jean-Pierre said in a statement.
President Biden arrived at Dover Air Force Base, as he headed back home to Rehoboth, Del., after testing positive for covid on July 17. (Video: The Washington Post)
He will be returning to Delaware where he will self-isolate and will continue to carry out all of his duties fully during that time, she said. The White House will provide regular updates on the Presidents status as he continues to carry out the full duties of the office while in isolation.
Relaying a statement from Bidens doctor, the White House said that the presidents symptoms began Wednesday afternoon.
He felt okay for his first event of the day, but given that he was not feeling better, point of care testing for COVID-19 was conducted, and the results were positive for the COVID-19 virus, the statement said, adding that Bidens vitals appeared normal.
Biden has taken his first dose of Paxlovid, the doctor said.
I feel good, Biden told reporters before boarding Air Force One. He was not wearing a mask.
Biden had been scheduled to speak Wednesday at a conference for UnidosUS, a leading Hispanic civil rights group.
The speech was set to begin at 1:30 p.m. local time, but Biden had been running more than an hour late when the groups president, Janet Murgua, told attendees he had called to say he would not be able to make it.
Biden also had to cancel a planned campaign stop scheduled for later Wednesday.
Earlier in the day, Biden had visited a local restaurant to tape an interview with Univision.
Biden, who previously tested positive for covid in July 2022 and experienced mild symptoms, was seen taking selfies with patrons before the interview.
His illness Wednesday comes as a covid summer wave washes over much of the United States. Coronavirus levels in wastewater were considered high or very high in 26 states, the Centers for Disease Control and Prevention reported last Thursday.
The CDC no longer collects comprehensive covid hospital admissions data. But the virus is becoming more prevalent in emergency departments, with the percentage of visits involving covid cases rising in recent weeks to 1.5 percent, the highest since February.
The bulk of new cases are caused by new variants, known as FLiRT and LB.1. The new variants are more effective than their predecessors at infecting people who have some immunity from previous infections or vaccination.
The CDC now advises people with covid to isolate until their overall symptoms have improved and they have been fever-free for 24 hours without the use of fever-reducing medication. The agency also advises precautions such as wearing masks and improving air circulation for an additional five days.
The Biden administration ended the public health emergency declaration for covid in May 2023 and has since rolled back efforts to contain transmission, including its free program of coronavirus tests by mail. Federal health authorities have prioritized vaccination as a way to prevent the worst outcomes of infections, now rolling out updated coronavirus vaccines in the fall alongside flu shots as part of a respiratory virus vaccination campaign.
But as Bidens case shows, coronavirus is not a strictly seasonal pathogen and causes periodic upticks throughout the year. It no longer overwhelms hospitals, but can cause more strain in fall and winter months when hospitals also confront rising flu and RSV cases. Covid is still one of the leading causes of death by infectious diseases and can cause lasting complications known as long covid, even in people who had mild cases.
Test tubes labelled "Monkeypox virus positive and negative" are seen in this image on May 23, 2022. Reuters
KINSHASA: The Democratic Republic of Congo is suffering an exponential rise in the number of monkeypox cases, the government said Saturday.
Government spokesperson Patrick Muyaya said the cumulative number of suspected cases had hit 11,166, including 450 deaths, for a fatality rate of four percent.
He said a report by the countrys health ministry revealed an exponential increase in the number of cases.
Muyaya added that the western province of Equateur was worst affected. The report said the government was taking a series of measures to combat the disease, notably medical care, monitoring of contacts with the respective health zones (and) promotion of community-based surveillance.
The report came just days after the World Health Organization warned of the threat to global health posed by the Mpox disease amid concern of a potential epidemic outbreak of a new, more deadly strain of the virus in the DRC.
The latest outbreak shows no sign of slowing down, said WHO head Tedros Adhanom Ghebreyesus. He cited 11,000 reported cases and 445 deaths, with children worst affected.
Rosamund Lewis, specialist in monkey pox at the WHO, also warned of the risk of the virus crossing borders.
The Democratic Republic of Congo is suffering an exponential rise in the number of monkeypox cases, the government said, Report informs referring to AFP.
Government spokesperson Patrick Muyaya said the cumulative number of suspected cases had hit 11,166, including 450 deaths, for a fatality rate of four percent.
He said a report by the countrys health ministry revealed an exponential increase in the number of cases.
Muyaya added that the western province of Equateur was worst affected.
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Thats the main takeaway from a study published in The New England Journal of Medicine. For the study, researchers analyzed medical records of nearly 450,000 people from the Department of Veterans Affairs health system who had COVID-19 diagnosed between March 1, 2020, and Jan. 31, 2022. Those patients were compared with around 4.7 million people who werent diagnosed with COVID-19 during the same time.
The researchers found that the lowest rates of long COVID (3.5%) were in people who were vaccinated against COVID-19. Of the people who were unvaccinated, 7.8% developed long COVID.
The study covered the original COVID-19 strain, along with Delta and Omicron strains. (The variants circulating nowlike LB.1 and FLiRT variants are off-shoots of the Omicron strain.) The rates of long COVID dropped over time, regardless of whether people were vaccinated, but the researchers said that was likely due to a combination of changes in the virus and other factors. Overall, the researchers found that the vaccine was responsible for nearly 72% of the drop in cases.
Meet the experts: Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York, infectious disease expert Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security, William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine
Its important to point out that the vaccine wasnt perfect at preventing long COVIDsome people who were vaccinated still developed long COVID, and some people with minor cases of COVID-19 went on to develop long COVID. But the vaccine did seem to be a major factor in lowering peoples risk of developing long COVID.
So, whats behind this? Doctors break it down.
Doctors have long recommended the COVID-19 vaccine to help lower the risk of developing long COVID, but data on how effective this is has been mixed.
In 2022, the United Kingdoms Health Security Agency released a scientific review of 15 studies and found that while most of the studies found that vaccinated people who contracted COVID-19 were less likely than their unvaccinated counterparts to develop long COVID, a few studies didnt find that the vaccine made a difference.
Why might the vaccine help? There are a few potential reasons. One is that the vaccine helps to lower the risk of developing severe illness, and severe illness is linked with a greater risk of having long COVID.
Current findings indicate that it has to do with the creation of chronic inflammation, says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine. Having COVID-19 can cause a strong inflammatory response, especially if you have a severe case, he says. If the vaccine tamps down on that inflammatory response, the risk of long COVID is also reduced, Dr. Schaffner says.
Infectious disease expert Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security, agrees. Vaccination induces ones immune system to mount a robust response against the virus, he says. The immune response may be the major factor in how the virus interacts with the host and a better immune response may preclude the development of long COVID in some manner.
But scientists still dont really know what the cause of long COVID is, Dr. Schaffner says.
Unfortunately, some people follow the recommendations to get vaccinated against COVID-19 and still end up developing long COVID. Vaccines lower the risk of long COVIDthey dont completely eliminate it, leading to the conclusion that other factors are involved, Dr. Adalja says.
Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York, agrees. Vaccination decreases the likelihood of long COVID, but its not perfect, he says. You still have a chance of developing long COVID.
Its all about lowering your risk of long COVID, Dr. Schaffner says. Were not dealing with perfection here, he says. Were dealing with reducing the risk.
Doctors recommend getting the COVID-19 vaccine to lower your risk of developing long COVID. Stay up to date with your vaccines, Dr. Schaffner says.
But vaccination levels in the U.S. havent been great lately. The most recent vaccine update became available in the fall of 2023, but less than a third of Americans got it. Were doing poorly with having people get the COVID-19 vaccine, Dr. Russo says.
The Centers for Disease Control and Prevention (CDC) recently recommended that all Americans six months and older get an updated COVID-19 vaccine in the fall when it becomes available, whether theyve been vaccinated against the virus in the past or not. Doctors say thats important, both to protect against severe disease and to lower your risk of developing long COVID, regardless of whether youre considered high risk for severe disease or not. We still dont really understand which individuals are eventually going to develop long COVID, Dr. Russo explains.
As of now, there are no specific treatments for long COVID. It is important to realize that long COVID is an umbrella term and not a specific disease process, Dr. Adalja says. For treatment to be successful, it will be necessary to actually untangle all the different things that are grouped under this umbrella. There may be different treatments for different types.
If you suspect that you have long COVID or have been diagnosed with the condition, Dr. Schaffner recommends trying to be seen at a specialized long COVID clinic. There, doctors who regularly treat patients with the condition should be able to offer a tailored approach to your treatment based on the latest research and what theyve seen be effective for patients.
We have guarded optimism about the future of long COVID treatment, Dr. Schaffner says. Most people with long COVID get better. They do it rather slowly, but they usually do get better.
Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Mens Health, Womens Health, Self, Glamour, and more. She has a masters degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.
Researchers from the University of Liverpool's Centre for Drug Safety Science have identified unpredicted T-cell immune responses to the adenoviral (Oxford/AstraZeneca and Janssen) COVID-19 vaccines, but not to the mRNA vaccines.
Using blood samples from healthy participants collected ten years prior to the COVID-19 pandemic, and therefore before any of the COVID-19 vaccines were developed, the researchers investigated how immune cells in blood including cells called T lymphocytes, which are important in mounting immune responses to viruses and bacteria responded to the different vaccine types.
The study showed that between 90-95% of participants who donated blood samples unexpectedly produced strong T-cell responses following exposure to the adenoviral vaccines in a laboratory setting.
The AstraZeneca ChAdOx1 vaccine, now no longer in use, was developed from the chimpanzee adenovirus because previous studies had shown a low frequency of antibodies (also called low seroprevalence) which reacted against this virus. This low frequency would therefore help in developing a protective immune response to the COVID-19 virus. The same rationale was used in the development of the Janssen Ad26.COV2-S COVID-19 vaccine. Both vaccines were shown to be efficacious against the virus in randomized controlled trials, and the AZ vaccine has been administered to more than 3 billion people globally.
This new finding of strong T cell responses in pre-pandemic blood samples is therefore unexpected and suggests that there is widespread cross-reactivity between the adenoviruses used in the vaccines and the adenoviruses that naturally circulate at high levels in the human population.
Study researchers note that consequences of this for the efficacy of the two vaccines is unclear and therefore further work is required to understand the mechanism of this cross-reactivity, and more carefully evaluate the prevalence of antibodies and T cells to circulating adenoviruses in people from different parts of the world.
This study was part of the Thrombotic Thrombocytopenia Syndrome (TTS) Consortium, supported in late 2021 by the National Institute for Health Research and backed by government funding from the Vaccine Taskforce to understand the reasons why there were rare instances of blood clotting with low platelets in some people who received the AstraZeneca and Janssen vaccines.
Chief Investigator of the TTS Consortium, Professor Sir Munir Pirmohamed, said: "The unexpected finding of pre-existing T cell reactivity towards the AstraZeneca and Janssen vaccines may have implications for why some people rarely developed TTS with these vaccines. There is now emerging data which shows that natural infection with adenoviruses, in the absence of COVID-19 vaccine administration, can also lead to the syndrome of blood clotting associated with low platelets."
Any adverse events linked to the T-cell responses identified in this study would have been experienced in the short period of time following vaccination, so these findings are not a cause for concern for those previously vaccinated with Oxford/Astrazeneca, say the researchers.
Lead researcher on the project, Dr Joshua Gardner, from the Centre for Drug Safety Science within the University's Department of Pharmacology and Therapeutics said: ''The findings of our study highlight the need to better understand the immune cross-reactivity of T cells between naturally circulating adenoviruses and those adenoviruses employed in the development of the COVID-19 vaccines. This may have implications for both the efficacy and safety of future vaccines, not only for COVID, but also for other infectious diseases".
Source:
Journal reference:
Gardner, J., et al. (2024). Identification of cross reactive T cell responses in adenovirus based COVID 19 vaccines.npj Vaccines. doi.org/10.1038/s41541-024-00895-z.
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