Another side effect linked with AstraZeneca COVID vaccine: All about VITT Amid concerns about Thrombotic Thrombocytopenia Syndrome (TTS), a side effect acknowledged by the drug maker in court documents, another side effect has emerged linked to AstraZeneca's COVID vaccine. According to a report, AstraZeneca's COVID vaccine may also cause Vaccine-Induced Immune Thrombocytopenia and Thrombosis (VITT), a blood clotting disorder. Can you avert hypertension if it runs in the family? Hypertension is often called the silent killer, especially when it runs in the family. Having a first-degree relative with this condition significantly increases your risk of developing it. Hypertension, or high blood pressure, is strongly influenced by genetic factors, making first-degree relatives (parents, siblings, and children) of hypertensive individuals more susceptible. Kartik Aaryan drops to just 7% body fat for Chandu Champion: Heres what it means to reduce body fat Kartik Aaryan reduces body fat to just 7% for his new project 'Chandu Champion'. It is important to know what to reduce body fat. Reducing body fat improves metabolic health, decreases the risk of heart disease, enhances physical performance, and alleviates joint stress. It also boosts energy, improves mood, and supports hormonal balance. Overall, it promotes better health, longevity, and a higher quality of life. Is 140/ 90 mmHg blood pressure normal? When the blood pressure is 140/90 mmHg or higher, it is classified as hypertension. Sub 120/80 mmHg is considered normal blood pressure. The four categories for blood pressure readings are as follows: stage 1 hypertension (130-139/80-89 mmHg), stage 2 hypertension (140/90 mmHg), raised (120-129/<80 mmHg), and normal (<120/80 mmHg). Fitness and diet secrets from 'Bridgerton' star Banita Sandhu Fans were delighted to see October's "Shiuli Iyer '' in the American historical romance television series "Bridgerton ''. Banita's social media profile is proof of how much the 26 year old actor loves being active. She is very active in off-beat outdoor activities like horse riding. Let's learn the secret behind Banita's glowing skin and fit physique. Why must you chew food 32 times? Chewing food 32 times aids digestion by breaking down food into smaller pieces, increasing nutrient absorption, and reducing digestive strain. It promotes satiety, helping to prevent overeating and supporting weight management. Thorough chewing also enhances saliva production, which contains enzymes crucial for the digestive process. What makes jeera pani the ultimate health drink? Jeera pani, or cumin water, aids digestion, relieves bloating, and reduces acidity. It boosts metabolism, aiding weight loss, and enhances detoxification. Rich in antioxidants, it supports immune health and regulates blood sugar levels. Drinking jeera pani can also improve hydration and promote overall wellness.
The researchers claimed on Thursday that British-Swedish pharma giant AstraZeneca's Covid-19 vaccine, made in collaboration with Oxford University has been found to raise the risk of vaccine-induced immune thrombocytopenia and thrombosis (VITT), which is a rare but fatal blood clotting disorder, reports news agency IANS. VITT emerged as a new disease following adenovirus vector-based Oxford-AstraZeneca vaccine-sold as Covishield in India and Vaxzevria in Europe-at the height of the Covid pandemic in 2021.
"An unusually dangerous blood autoantibody directed against a protein termed platelet factor 4 (or PF4)" was found as the reason for VITT.
In separate research in 2023, scientists from Canada, North America, Germany and Italy described a virtually identical disorder with the same PF4 antibody that was fatal in some cases after natural adenovirus (common cold) infection. In a new research now, Flinders University in Australia and other international experts found that the PF4 antibodies in both adenovirus infection-associated VITT and classic adenoviral vector VITT share identical molecular fingerprints or signatures.
"Indeed, the pathways of lethal antibody production in these disorders must be virtually identical and have similar genetic risk factors," said Professor Tom Gordon from FlindersThe researcher noted that the "findings have the important clinical implication that lessons learned from VITT are applicable to rare cases of blood clotting after adenovirus (a common cold) infections, as well as having implications for vaccine development".
In 2022, the same team had in a study "cracked the molecular code of the PF4 antibody and identified a genetic risk factor".
Their new findings, published in the New England Journal of Medicine, also have important implications for improving vaccine safety. The research comes after AstraZeneca "accepted, in a legal document submitted to the High Court in February, that its Covid vaccine 'can, in very rare cases, cause Thrombotic Thrombocytopenic Syndrome (TTS)."
TTS is a rare side effect that can cause people to have blood clots and a low blood platelet count.
(With input from agencies)
Federal health officials Wednesday suspended funding to a U.S. research organization linked to investigations about the novel coronaviruss origins, saying the move is necessary to protect the public interest given the organizations failure to monitor virus experiments in a Chinese lab before the pandemic.
Federal officials also are seeking to block future funding to EcoHealth Alliance, which worked with the Wuhan Institute of Virology in China, citing new evidence about EcoHealths actions that emerged ahead of a contentious congressional hearing this month.
Breadcrumb Trail Links
Democrats and Republicans now agree that a viral research funder swindled the public on the (genuine but unproven) possibility of a lab leak
Published May 18, 2024 Last updated 20hours ago 2 minute read
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On Wednesday, the United States Department of Health and Human Services (HHS)issued a legal notice to the EcoHealth Alliance, the disease research NGO that has found itself at the heart of a political struggle over COVID-19 origins. The HHS letter amounts to a warning that the Biden administration intends to debar EcoHealth, a major funder of Chinese coronavirus research activity, from receipt of U.S. federal funding for some undetermined period.
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The congressional caucuses of the two major parties are still divided, and still sniping at each other, over COVID-origins questions. You can see this for yourself by reading twin reports issued this month by the House select subcommittee studying oversight and accountability aspects of the pandemic one of which is the question whether the U.S. government might have accidentally paid for a megacidal epidemic through EcoHealth and its links to Chinas Wuhan Institute of Virology (WIV).
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The majority report criticizes EcoHealth president Peter Daszak for obstructing and obfuscating origins investigations, hiding awkward and shocking facts about the Chinese research activity Americans were paying for and acting with unspeakably poor scientific integrity. It also throws in a bunch of praise for former president Donald Trump.
Meanwhile,a minority report issued by the committees Democratswarns against praising Trump or accepting kooky biowarfare theories of COVID origins. But it concurs emphatically with the majoritys judgment on EcoHealth and Daszak. On some points, and particularly on Daszaks sleazy role in organizing the early publicity effort to deny the possibility of a laboratory accident in Wuhan (see page 28), the Democratic report is harsher and more specific.
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In other words, one thing everyone now agrees on is that Daszak is a wrong un who worked to save his behind by swindling politicians, media and the public on the (genuine but unproven) possibility of a lab leak. EcoHealth clearly felt itself to be serving a higher purpose in funding Chinese research on coronaviruses and particularly bat coronaviruses, but its oversight of the WIVs safety characteristics and its knowledge of WIV research detailshave turned out to be culpably feeble. All of this adds up to somethingvery much like jailing Al Capone for tax evasion: EcoHealth may get the equivalent of a scientific death penalty because of the piss-poor quality of its reporting to the authorities.
The emergence of an awkward bipartisan consensus on EcoHealth really a three-way consensus now that the executive branch is acting is obviously significant. So too is the presence of a strong component, within the liberal mainstream media, of a group of lab-leak re-revisionists. Well, Im not sure if thats the right word, but I dont quite know what to call these people. Theyre just journalists who knew from the start that there is a recorded history of harmful virologist lab accidents; who didnt like the way the lab-leak theories were impulsively suppressed by means of social media censorship and catcalls of racism; and who thoughtthere was a story in it all. Two of these writers,New York Timescolumnist Zeynep TufekciandVanity Fairs Katherine Eban, have new long Twitter threads reacting to the HHS announcement and outlining the sordid background.
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After the first Omicron wave, many of the risks of Covid infection changed. Before February 2022, wearing face masks and being over 70 were credited with a reduced risk of being infected by others but not after that, according to a new study at the University of East Anglia (UEA) in Norwich, the UK.
The analysis of official data found that several risk factors for infection altered significantly as the dominant variant in the UK and most countries around the world changed from Delta to Omicron in December 2021. These included wearing a mask, a history of foreign travel, household size, whether people were working or retired, and contact with children or people over the age of 70. In addition, traveling abroad was not associated with increased risk prior to February 2022 but then became a significant risk.
Lead author Prof. Paul Hunter of Norwich Medical School said: Early in the pandemic, there were many studies published looking at risk factors for catching the new Coronavirus, but far fewer studies after the first year or so. Our research shows that there were changes in some risk factors around the time that the Omicron BA.2 variant became dominant.
Co-author Dr. Julii Brainard said: This isnt totally surprising because laboratory evidence suggests that the Omicron variant was better able to infect the cells lining the upper respiratory tract than previous variants, and so be more transmissible. Management of infection risk needs to be agile, adapting to epidemic development and better-quality information when it emerges. To prevent infections, we need to have a good view of which factors might be most or least relevant. If those factors can change, we need to be alert to that happening.
The team published the study in the journal PLOS titled Changing risk factors for developing SARS-CoV-2 infection from Delta to Omicron.
The researchers analyzed data available from Englands Office for National Statistics (ONS) COVID survey, which compared infection rates with an ongoing household survey of the population to estimate the number of people with infections.
From November 2021 to May 2022, the ONS also asked people questions about their circumstances and habits to see if those factors could be linked to the risk of positivity. We used this dataset to look for constancy or change in the importance and direction of potential risk factors for testing positive. We applied a statistical method called meta-regression to do this, Hunter added.
In November 2021, always wearing face masks at work, school, or in enclosed spaces was connected with a reduced risk of being infected in both adults and children, but after the first Omicron wave, it was not. Living in a house with five or more people was a risk at the beginning, but by the end of the study period, people in larger households (four and above) had negligibly greater risk than people living in single-person households.
Early overseas travel was not associated with increased risk, but later on, it was. Working in health or social care or in contact with others was often found to be important in the first year of the pandemic but was not associated with an overall higher or changing risk of infection in the study period. Being a member of an ethnic minority was strongly associated with increased risk in the first few months of the UK epidemic. Still, it posed a lower risk and no significant trend change during the studys full monitoring period.
Being retired was associated with reduced risk compared to those in work overall, but any protective effect had disappeared by February 27, 2022, which coincided with the start of the second Omicron wave. By the end of February 2022, it became apparent that there was a decrease in risk for adults living with children aged 16 or under. People under 70 who lived with someone aged 70 or older initially had a lower likelihood of testing positive, but this protective effect diminished by about mid-February 2022.
The researchers said the balance of evidence shows that wearing face coverings reduce transmission of respiratory infections in community settings and reduce transmission of the virus, but the question is by how much.
Systematic review of pre-pandemic evidence and analysis of original survey data during the pandemic both indicated that mask-wearing could or did reduce transmission by about 19%, but these conclusions were derived mainly from data prior to the emergence of Omicron variants.
This latest research found that prior to Omicron BA.2, never wearing a mask was associated with an increased risk of around 30% in adults and 10% in children. However, by the second Omicron wave (mid-to-late February 2022 onwards), mask-wearing had no protective effect on adults and possibly increased the risk of infection in children.
It should not be a surprise that risk factors change during a pandemic due to a highly infectious disease with a short duration of immunity like COVID-10, Hunter said. We offer some possible explanations for why the changes may have happened, but we would need more focused research to understand for sure why there were changes in some risk factors, Brainard concluded.
The "FLiRT" COVID-19 variants are a new group of strains circulating in the United States, which now account for over one in four cases nationwide.
Although cases and hospitalizations have been down, the virus that causes COVID-19 continues to mutate and give rise to a seemingly endless stream of new variants.
The latest to gain attention, KP.2 and KP.1.1, are part of a new family of subvariants called "FLiRT," which were detected in wastewater samples earlier this spring and are now causing an increasing proportion of cases.
According to experts, KP.2 and KP.1.1 may be more transmissible and better at escaping prior immunity than previous variants, which has sparked concern about a possible summer wave.
The variants have also sparked plenty of reactions and jokes on social media. Are we "flirting" with dangerous new variant? Why is it called FLiRT in the first place?
KP.2 and KP.1.1 are spinoffs of the omicron subvariant JN.1.11.1, which is a direct descendant of JN.1, the dominant strain for most of the winter, TODAY.com previously reported.
KP.2 and KP.1.1 are similar to JN.1, but they picked up additional mutations which appear to be giving the new strains an advantage over other variants, Dr. Albert Ko, infectious disease physician and professor of public health, epidemiology and medicine at Yale School of Public Health, previously told TODAY.com.
Last month, KP.2 rapidly overtookJN.1, which drove asurge in COVID cases last winter, to become the dominant strain in the U.S. Currently, KP.2 accounts for over 25% of cases, according to the latest data fromthe U.S. Centers for Disease Control and Prevention.
"I think these two mutations together are making KP.2 a better virus in that it maintains its ability to transmit, but also now evades some of the pre-existing immunity in the population, Andrew Pekosz, Ph.D., virologist at Johns Hopkins University, previously told TODAY.com.
As KP.2 and KP.1.1 gained traction, scientists on social media came up with a catchy new nickname, FLiRT," to use instead of the mouthful of letters and numbers.
It's distinct from other unofficial variant names Pirola, Eris, Arcturus, and Kraken which seem to fall into a theme of Greek mythology and constellations.
The name "FLiRT" was reportedly coined in March on X, formerly known as Twitter, by T Ryan Gregory, Ph.D., a biologyprofessorat the University of Guelph in Ontario. Gregory regularly posts about the evolution of SARS-CoV-2, the virus that causes COVID-19, and is behind many of the other popular variant nicknames.
Not surprisingly, the new strains arent spread by winking, giving compliments, or other signals of romantic interest and attraction. They have nothing to do with flirting at all.
The name FLiRT is based on the technical names for the variants' spike protein mutations, Pekosz said. These two mutations are at position 456 (F for L) and position 346 (R for T), Pekosz said. The "FL" and "RT" were combined into "FLiRT," according to the Infectious Disease Society of America.
When new variants emerge, they are described using a combination of letters and numbers, such as KP.2, JN.1, or HV.1. These letters and numbers refer to the variants Pango lineage, which is similar to a family tree, with lineages descending from the parental strain, according to the CDC.
A group of closely related viruses is called a lineage and the direct descendants of each variant are referred to as a sublineages for example, BA.2.75 is a sublineage of BA.2. These lineages are named using an alphabetical prefix, such as BA or XBB, followed by a numerical suffix (such as .1 or .1.1.5), per the CDC.
Think of KP.2 and KP.1.1 as branches extending from the JN.1 branch, which is a direct descendent of BA.2.86 or Pirola.
As the virus continues to mutate and change, these technical names can become long and difficult to remember or say. That's where nicknames come in handy.
In 2021, the World Health Organization introduced a simpler system to label key variants. Each new variant of interest and variant of concern would be named after letters of the Greek alphabet. These include the alpha, beta, delta and omicron lineages.
Omicron (B.1.1.529) began circulating in the fall of 2021. Since then, the omicron virus variant has mutated and given rise to new subvariants. All of the COVID-19 strains that have emerged and gained dominance since 2022 have been descendants of omicron.
These include omicron BA.2, BA.4 and XBB. Once again, the clunky combinations of letters and numbers are used to distinguish between variants. Nicknames like FLiRT help make sense of the "variant soup," as Gregory wrote in a tweet.
Despite it's playful name, the new set of COVID-19 variants are nothing to joke about. It's important to take precautions against COVID-19 and keep up to date with vaccinations to prevent severe disease and complications.
Caroline Kee is a health reporter at TODAY based in New York City.
Singapore is seeing a new Covid-19 wave as the authorities recorded more than 25,900 cases from May 5 to 11 even as Health Minister Ong Ye Kung on Saturday advised the wearing of masks again.
We are at the beginning part of the wave where it is steadily rising, said Ong. So, I would say the wave should peak in the next two to four weeks, which means between mid- and end of June, The Straits Times newspaper quoted the minister as saying.
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The Ministry of Health (MOH) said the estimated number of Covid-19 cases in the week of May 5 to 11 rose to 25,900 cases, compared with 13,700 cases in the previous week.
The average daily Covid-19 hospitalisations rose to about 250 from 181 the week before.
The average daily intensive care unit (ICU) cases remained low at three cases, compared with two cases in the previous week.
The MOH said that to protect hospital bed capacity, public hospitals have been asked to reduce their non-urgent elective surgery cases and move suitable patients to transitional care facilities or back home through Mobile Inpatient Care@Home, an alternative inpatient care delivery model that offers clinically suitable patients the option of being hospitalised in their own homes instead of a hospital ward.
Ong urged those who are at greatest risk of severe disease, including individuals aged 60 years and above, medically vulnerable individuals and residents of aged care facilities, to receive an additional dose of the Covid-19 vaccine if they have not done so in the last 12 months.
Ong said that if the number of Covid-19 cases doubles one time, Singapore will have 500 patients in its healthcare system, which is what Singapore can handle. However, if the number of cases doubles a second time, there will be 1,000 patients, and that will be a considerable burden on the hospital system, he pointed out.
One thousand beds is equivalent to one regional hospital, Ong said. So, I think the healthcare system has to brace ourselves for what is to come.
There are no plans for any form of social restrictions or any other mandatory kind of measures for now, as Covid-19 is treated as an endemic disease in Singapore, he said, adding that imposing additional measures would be a last resort.
Ong said that with Singapore being a transport and communications hub, it will be one of the cities to get a wave of Covid-19 earlier than others.
So, Covid-19 is just something that we have to live with. Every year, we should expect one or two waves, he said.
Globally, the predominant Covid-19 variants are still JN.1 and its sub-lineages, including KP.1 and KP.2. Currently, KP.1 and KP.2 account for over two-thirds of cases in Singapore.
As of May 3, the World Health Organisation has classified KP.2 as a variant under monitoring. There are currently no indications, globally or locally, that KP.1 and KP.2 are more transmissible or cause more severe disease than other circulating variants, the MOH said.
However, members of the public are urged to stay updated with vaccinations to protect themselves against current and emerging virus strains. The MOH said that to date, about 80 per cent of the local population have completed their initial or additional dose, but have not received a dose within the last year.
The ministry added that since Covid-19 vaccination started in 2020 to 2021, the vaccines have consistently been proven to be safe and effective in protecting individuals from severe illness. Billions of doses have been administered globally, and safety monitoring internationally has shown that the vaccine is safe, it said.
There have also been no long-term safety concerns with Covid-19 vaccination, and adverse effects from vaccines, including the mRNA vaccines, have all been observed to occur shortly after vaccination, the ministry added.
Published On:
May 18, 2024
ATLANTA COVID-19 levels are about the lowest they've ever been in the United States, but another new crop of virus variants once again threatens to disrupt the downward trend as the country heads into summer.
KP.2 one of the so-called FLiRT variants has overtaken JN.1 to become the dominant coronavirus variant in the United States, according to data from the Centers for Disease Control and Prevention. Data through May 11 shows that it's responsible for more than a quarter of cases in the country, which is nearly twice as many as JN.1. A related variant, KP.1.1, has caused about 7% of cases, CDC data shows.
FLiRT variants are offshoots of the JN.1 variant all part of the broader Omicron family that caused this winter's wave. The acronym in the name refers to the locations of the amino acid mutations that the virus has picked up some in places that help it evade the body's immune response and others that help it become more transmissible.
COVID-19 variants are "accumulating mutations that do one of two things: They either cause antibodies that you've accumulated from vaccination or infection to no longer bind to the virus we call that escape from immunity or they increase the strength in which the viruses bind to cells," said Dr. Andy Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health.
This has become a familiar pattern in the way the virus that causes COVID-19 continues to evolve, but experts say we still don't know enough to predict exactly where the changes will occur next or how they will affect the way the virus moves through the population.
The mutations of the FLiRT variants make increased transmissibility and a possible summer wave a real threat. COVID-19 is settling into some seasonal patterns, which have included a summer bump in years past, but the exact level of risk for this year is unclear.
"We've had some variants in the past that start out kind of strong and then don't take over. These subvariants could progressively become dominant, or they could get up to accounting for somewhere between 20% and 40% of the cases and then just stay there. We just have to see," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University. "The virus continues to be in charge. It's going to tell us what it's going to do. All of our crystal balls are rather cloudy."
COVID-19 surveillance has scaled back significantly since the U.S. public health emergency ended a year ago, which also adds to the uncertainty. But the data that is available is consistent. For now, wastewater surveillance suggests that viral activity is very low and decreasing in all regions of the country, and COVID-19 hospitalization rates remain extremely low.
"We learned from the laboratories that FLiRT variants appeared, so far, to be as transmissible as the other Omicron subvariants, which means they're really quite contagious. But they do not appear to be producing more severe disease or any sort of illness that's distinctive from the point of view of clinical presentation symptoms," Schaffner said.
As of May 1, the requirement for all hospitals to report COVID-19 data to the federal government has expired. But Schaffner's Vanderbilt University Medical Center is part of a CDC-run surveillance network that continues to track trends based on a sample of hospitals that cover about 10% of the U.S. population. COVID-19 hospitalization rates have fallen from nearly eight new admissions for every 100,000 people in the first week of the year to about one new admission for every 100,000 people at the end of April, the data shows.
While the FLiRT variants pose some risk this summer, experts remain focused on what might happen in the fall.
"If I were to predict, I would say that this might result in a few extra cases, a small surge this summer. But it's really going to be about which variant is around when we get to the fall," Pekosz said. "The fall is probably when we should expect to see a surge of COVID cases. And if we have a variant around there that has a lot of these mutations that avoid immunity, then the potential in the fall to have a larger surge is greater."
The fall and winter pose a greater risk because of the immunity that has built up in the population, he said.
"The virus now needs better conditions to transmit, and those better conditions to transmit are probably going to happen in the fall when weather gets cooler, people are spending more time indoors and they're more likely to be in environments where respiratory virus transmission occurs more efficiently."
Research published Wednesday in the medical journal JAMA is a reminder of the burden that COVID-19 continues to have in the U.S. This winter, while COVID-19 hospitalization rates were far lower than they were in earlier years, it was still deadlier than the flu. A study of thousands of hospital patients found that 5.7% of COVID-19 patients died, compared with 4.2% of those hospitalized for influenza. In other words, COVID-19 carried about a 35% higher risk of death than flu.
People who received the latest COVID-19 vaccine this past fall may still have some protection against the latest variants; that vaccine targeted a different strain but was found to be similarly effective against JN.1, and experts say that some of those benefits may extend to its FLiRT relatives. People who had a recent infection especially since the start of the year, when JN.1 was prominent may also have some protection. But immunity wanes over time.
For now, experts say, risk remains relatively low.
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Health-care workers received the first doses of the COVID-19 vaccine in December 2020. A study by researchers at Washington University School of Medicine in St. Louis has found that repeat vaccination with updated versions of the COVID-19 vaccine promotes the development of antibodies that neutralize a wide range of variants of the virus that causes COVID-19, as well as related coronaviruses.
Credit: Matt Miller/Washington University
The COVID-19 pandemic is over, but the virus that caused it is still here, sending thousands of people to the hospital each week and spinning off new variants with depressing regularity. The viruss exceptional ability to change and evade immune defenses has led the World Health Organization (WHO) to recommend annual updates to COVID-19 vaccines.
But some scientists worry that the remarkable success of the first COVID-19 vaccines may work against updated versions, undermining the utility of an annual vaccination program. A similar problem plagues the annual flu vaccine campaign; immunity elicited by one years flu shots can interfere with immune responses in subsequent years, reducing the vaccines effectiveness.
A new study by researchers at Washington University School of Medicine in St. Louis helps to address this question. Unlike immunity to influenza virus, prior immunity to SARS-CoV-2, the virus that causes COVID-19, doesnt inhibit later vaccine responses. Rather, it promotes the development of broadly inhibitory antibodies, the researchers report.
The study, available online in Nature, shows that people who were repeatedly vaccinated for COVID-19 initially receiving shots aimed at the original variant, followed by boosters and updated vaccines targeting variants generated antibodies capable of neutralizing a wide range of SARS-CoV-2 variants and even some distantly related coronaviruses. The findings suggest that periodic re-vaccination for COVID-19, far from hindering the bodys ability to recognize and respond to new variants, may instead cause people to gradually build up a stock of broadly neutralizing antibodies that protect them from emerging SARS-CoV-2 variants and some other coronavirus species as well, even ones that have not yet emerged to infect humans.
The first vaccine an individual receives induces a strong primary immune response that shapes responses to subsequent infection and vaccination, an effect known as imprinting, said senior authorMichael S. Diamond, MD, PhD, the Herbert S. Gasser Professor of Medicine. In principle, imprinting can be positive, negative or neutral. In this case, we see strong imprinting that is positive, because its coupled to the development of cross-reactive neutralizing antibodies with remarkable breadth of activity.
Imprinting is the natural result of how immunological memory works. A first vaccination triggers the development of memory immune cells. When people receive a second vaccination quite similar to the first, it reactivates memory cells elicited by the first vaccine. These memory cells dominate and shape the immune response to the subsequent vaccine.
In the case of the flu vaccine, imprinting has negative effects. Antibody-producing memory cells crowd out new antibody-producing cells, and people develop relatively few neutralizing antibodies against the strains in the newer vaccine. But in other cases, imprinting can be positive, by promoting the development of cross-reactive antibodies that neutralize strains in both the initial and subsequent vaccines.
To understand how imprinting influences the immune response to repeat COVID-19 vaccination, Diamond and colleagues including first author Chieh-Yu Liang, a graduate student, studied the antibodies from mice or people who had received a sequence of COVID-19 vaccines and boosters targeting first the original and then omicron variants. Some of the human participants also had been naturally infected with the virus that causes COVID-19.
The first question was the strength of the imprinting effect. The researchers measured how many of the participants neutralizing antibodies were specific for the original variant, the omicron variant or both. They found that very few people had developed any antibodies unique to omicron, a pattern indicative of strong imprinting by the initial vaccination. But they also found few antibodies unique to the original variant. The vast majority of neutralizing antibodies cross-reacted with both.
The next question was how far the cross-reactive effect extended. Cross-reactive antibodies, by definition, recognize a feature shared by two or more variants. Some features are shared only by similar variants, others by all SARS-CoV-2 variants or even all coronaviruses. To assess the breadth of the neutralizing antibodies, the researchers tested them against a panel of coronaviruses, including SARS-CoV-2 viruses from two omicron lineages; a coronavirus from pangolins; the SARS-1 virus that caused the 2002-03 SARS epidemic; and the Middle Eastern Respiratory Syndrome (MERS) virus. The antibodies neutralized all the viruses except MERS virus, which comes from a different branch of the coronavirus family tree than the others.
Further experiments revealed that this remarkable breadth was due to the combination of original and variant vaccines. People who received only the vaccines targeting the original SARS-CoV-2 variant developed some cross-reactive antibodies that neutralized the pangolin coronavirus and SARS-1 virus, but the levels were low. After boosting with an omicron vaccine, though, the cross-reactive neutralizing antibodies against the two coronavirus species increased.
Taken together, the findings suggest that regular re-vaccination with updated COVID-19 vaccines against variants might give people the tools to fight off not only the SARS-CoV-2 variants represented in the vaccines, but also other SARS-CoV-2 variants and related coronaviruses, possibly including ones that have not yet emerged.
At the start of the COVID-19 pandemic, the world population was immunologically nave, which is part of the reason the virus was able to spread so fast and do so much damage, said Diamond, also a professor of molecular microbiology and of pathology & immunology. We do not know for certain whether getting an updated COVID-19 vaccine every year would protect people against emerging coronaviruses, but its plausible. These data suggest that if these cross-reactive antibodies do not rapidly wane we would need to follow their levels over time to know for certain they may confer some or even substantial protection against a pandemic caused by a related coronavirus.
Experimental study
People
Imprinting of serum neutralizing antibodies by Wuhan-1 mRNA vaccines.
15-May-2024
M.S.D. is a consultant or advisor for Inbios, Vir Biotechnology, IntegerBio, Moderna, Merck, and GlaxoSmithKline. The Diamond laboratory has received additional unrelated funding support in sponsored research agreements from Vir Biotechnology, Emergent BioSolutions, and IntegerBio. G.A.A., S.M.E, and D.K.E. are employees of and shareholders in Moderna, Inc. J.E.C. has served as a consultant for Luna Biologics, is a member of the Scientific Advisory Boards of CompuVax and Meissa Vaccines and is Founder of IDBiologics. The Crowe laboratory at Vanderbilt University Medical Center has received sponsored research agreements from Takeda Vaccines, IDBiologics, and AstraZeneca. Vanderbilt University has applied for a patent concerning antibodies that are related to this work (U.S. Provisional Patent Application No. 63/513,255). All other authors declare no competing interests.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
