WASHINGTON, June 28 (BUS) – US health authorities face a critical decision: whether to introduce new COVID-19 booster footage this fall that will be tweaked to better match recent changes to the shape-shifting coronavirus.
Moderna and Pfizer have tested the updated shots against a highly contagious omicron variant, and FDA advisers will debate Tuesday whether it’s time to make a change — paving the way for similar moves by other countries.
“This science is at its toughest,” FDA Vaccines Head Dr. Peter Marks told The Associated Press, adding that a final decision is expected within days of the advisory panel’s recommendation.
Current COVID-19 vaccines have saved millions of lives around the world in just their first year of use. And the Moderna and Pfizer shots still provide powerful protection against the worst outcomes — severe illness and death — especially after a booster dose, the AP reports.
But these vaccines target the original strain of coronavirus, and between the decline in immunity and a relentless barrage of variants, protection against infection has decreased significantly. The challenge is to determine whether modified enhancers offer a good chance of stopping another mutation when there is no way to predict which mutation will be the main threat.
In an analysis prepared for Tuesday’s meeting, FDA officials acknowledged that targeting last winter’s version of Omicron is “somewhat outdated” as it has already been replaced by its more contagious cousin.
“Obviously we want to get it right enough,” Marks said, “so we can get an entire season of protection with another shot.”
Many experts say the updated boosters promise at least a little more benefits.
“It is more likely to be beneficial” than simply giving extra doses of today’s vaccine, said epidemiologist William Hanage of the Harvard TH Chan School of Public Health.
This is assuming the virus doesn’t throw another curve ball.
Dr Eric Topol, president of the Scripps Research Translational Institute, has urged specialization of government pressure for next-generation vaccinations.
Adding to the concern about the winter wave of COVID-19 is that about half of Americans who qualify for a very important first booster shot never get it. The updated version may tempt some of them.
“We need to change our expectations,” said Dr. William Moss of the Johns Hopkins Bloomberg School of Public Health, noting that studies early in the pandemic raised unrealistic hopes of preventing even the mildest infections. “Our strategy cannot be every two months, even every six months, booster doses to prevent infection.”
The best candidates are what scientists call “bivalent” shots – a combination of the original vaccine plus Omicron protection.
That’s because the original vaccines induce the production of some virus-fighting antibodies strong enough to cross-react with newer mutations — in addition to their proven benefits against severe disease, said University of Pennsylvania immunologist E. John Weiry.
“Being able to push the reinforcement response a little bit in one direction or the other without losing the nucleus is really important,” he said.
Moderna and Pfizer found that the mixed shots significantly boosted levels of omicron-resistant antibodies in adults who had already received three vaccinations, more than just giving another regular dose.
The recipients also developed antibodies that can fight the newer relatives of the omicron called BA.4 and BA.5, although not nearly as many. It is not clear how much protection will be translated and for how long.
Antibodies are the main first layer of defense that forms after vaccination or a previous infection. They can prevent infection by recognizing the coronavirus’s outer envelope – the spike protein – and preventing it from entering your cells.
But the antibodies dwindle naturally and each new type comes with a different-looking spike protein, giving it a better chance of evading detection by the remaining antibodies.
Separate studies published this month in Nature and the New England Journal of Medicine show that newer relatives of the omicron are better at evading antibodies — both in the vaccine and in people who recovered from the original omicron.
This first person booster was supposed to strengthen an immune memory, which helps explain why protection from hospitalization and death has been shown to be more permanent. If the virus infiltrates the antibodies, various defenders called T cells fire into action, attacking the infected cells to curb the disease.
“The T cells recognize the virus in a fundamentally different way,” Benz Wehrey said, not looking for a convincing spike protein, but for parts of the virus that haven’t changed much so far.
However, as people get older, all parts of their immune system gradually weaken. There is little data on how long it takes for T cells to protect against COVID-19 or how it varies with different mutations or vaccines.
Wehrey and dozens of other scientists recently asked the FDA to stop focusing solely on antibodies and start measuring T cells when it decides on a vaccination strategy.
The Biden administration has made it clear that it needs Congress to provide more money so that if the Food and Drug Administration clears out the updated boosters, the government can buy enough for every American who wants one. Dr. Anthony Fauci, the government’s top infectious disease expert, told Congress last week that more research funding is also important to create better next-generation vaccines, such as nasal versions that might better prevent infections in the nose or more shots of resistant variants.
“The virus is changing and we need to keep up with that,” Fauci said.