U.S. health authorities are facing a critical decision: whether to offer new COVID-19 booster shots this fall that are modified to better match recent changes of the shape-shifting coronavirus.
Moderna and Pfizer have tested updated shots against the super-contagious omicron variant, and advisers to the Food and Drug Administration will debate Tuesday if it’s time to make a switch — setting the stage for similar moves by other countries. This is science at it’s toughest,” FDA vaccine chief, Dr. Peter Marks said to The Associated Press. He added that a decision will be made within days following the recommendation of an advisory panel.
Current COVID-19 vaccines saved millions of lives around the world in just their first year of use. Moderna or Pfizer vaccines offer protection from severe illness, death and even death.
But those vaccines target the original coronavirus strain and between waning immunity and a relentless barrage of variants, protection against infections has dropped markedly. It’s difficult to decide if boosters can be tweaked in a way that will reduce another outbreak. There is no way of knowing which mutations are the most dangerous.
In an analysis prepared for Tuesday’s meeting, FDA officials acknowledged targeting last winter’s version of omicron is “somewhat outdated” since it already has been replaced by its even more contagious relatives.
“We would obviously like to get it right enough,” Marks said, so that with one more shot “we get a full season of protection.”
Many experts say updated boosters promise at least a little more benefit.
” “It’s more likely that it will be helpful” than giving extra doses of today’s vaccine. William Hanage, an epidemiologist at Harvard T.H. Chan School of Public Health.
That assumes the virus does not throw another curveball. We’re not trying to get ahead, which can be so frustrating — that we haven’t found a better vaccine against this virus,” stated Dr. Eric Topol of Scripps Research Translational Institute. He has called for a significant government push for the next generation immunizations.
Adding to concern about a winter COVID-19 wave is that about half of Americans eligible for that all-important first booster dose never got it. Some might be tempted by an updated version.
But, “we need to change our expectation,” Dr. William Moss of Johns Hopkins Bloomberg School of Public Health stated. He noted that early studies had shown unrealistic expectations of preventing even mild infections. “Our strategy can’t be booster doses every couple of months, even every six months, to prevent infections.”
The top candidates are what scientists call “bivalent” shots — a combination of the original vaccine plus omicron protection.
That’s because the original vaccines do spur production of at least some virus-fighting antibodies strong enough to cross-react with newer mutants — in addition to their proven benefits against severe disease, said University of Pennsylvania immunologist E. John Wherry.
” “It is important to be able push the boost response in one direction but not lose the core.” he stated.
Moderna found that their combination shots significantly increased levels of anti-omicron antibodies in adults who had already received three vaccines. This was more than just giving another dose.
Recipients also developed antibodies that could fight omicron’s newest relatives named BA. 4 and BA. 5, although not nearly as many. It’s not clear how much protection that will translate into, and for how long.
Antibodies are a key first layer of defense that form after vaccination or a prior infection. They can prevent infection by recognizing the outer coating of the coronavirus — the spike protein — and blocking it from entering your cells.
But as antibodies decrease, each variant of the coronavirus has a unique spike protein. This gives it an advantage over remaining antibodies. Separate studies published this month in Nature and the New England Journal of Medicine show the newest omicron relatives are even better at dodging antibodies — both in the vaccinated and in people who recovered from the original omicron.
That first booster people were supposed to get strengthened immune memory, helping explain why protection against hospitalization and death is proving more durable. If the virus sneaks past antibodies, different defenders called T cells spring into action, attacking infected cells to curb illness.
“T cells recognize the virus in a fundamentally different way,” not hunting for disguised spike protein but for parts of the virus that so far haven’t been altered as much, said Penn’s Wherry.
Still, as people get older, all parts of their immune system gradually weaken. There’s little data on how long T cell protection against COVID-19 lasts or how it varies with different mutations or vaccines.
Wherry and dozens of other scientists recently petitioned the FDA to quit focusing solely on antibodies and start measuring T cells as it decides vaccination strategy.
The Biden administration has made clear that it needs Congress to provide more money so that if the FDA clears updated boosters, the government can buy enough for every American who wants one. And Dr. Anthony Fauci, the government’s top infectious disease expert, told Congress last week more research funding also is critical to create better next-generation vaccines, such as nasal versions that might better block infection in the nose or more variant-proof shots.
“The viruses are constantly changing, and it is important that we keep up,” Fauci said.
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.
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