The agency notes that if a more dangerous COVID variant were to emerge, it might reconsider the vaccine strain at other times of the year on an "as-needed and emergent basis."
Some immunologists and vaccine researchers say simplifying the process along the lines of the flu vaccine is appropriate at this point in the pandemic. However, many questions remain about emerging booster strategy.
"As far as the tools that we have right now, I think it just makes the most sense to plan to update each year as close as we can to the currently circulating variant," says Deepta Bhattacharya, an immunologist at the University of Arizona. "So I think all the things the FDA is considering make a lot of sense."
Questions about efficacy of updated shots
There's an intense debate about the wisdom of updating the COVID vaccines regularly to try to match new variants. Some researchers question whether that really makes the vaccines more effective. They also argue that the low demand for the latest booster shows the public has little appetite for continued boosting with the vaccines, even if they've been updated with new strains.
"The public is voting with their arms if you will and said, 'No. I'm not going to get this. This doesn't make sense to us,'" says Dr. Gregory Poland, a vaccine researcher at the Mayo Clinic.
While endorsing continued boosters for those at high risk, such as the elderly, some question whether the current bivalent vaccines updated to target omicron have enhanced protection compared to the original vaccines. Most people are still well-protected against severe disease by the immunity they already have, they say.
"We have no solid data about the performance of the bivalent boosters," says John Moore, an immunologist at Weill Cornell Medical College. "The hard evidence is lacking, and the evidence that is out there is at the very least inconclusive and to me trends towards saying the bivalent boosters were little if no better."
Moore and others argue that the virus is changing so fast that it's pointless to constantly try to match the vaccines to the latest variants.
"We shouldn't really be chasing these variants, which are evanescent and are often gone by the time you've created the vaccine," says Dr. Paul Offit of the University of Pennsylvania, one of the FDA's advisers.
Offit and others also question whether everyone will necessarily need to be boosted regularly, or just those at high risk, like the elderly.
Arguments for alternate vaccine strategies
Critics of the FDA's proposed new strategy argue that it would be better to invest in developing better vaccines that might be more appealing to people, and in campaigns to get more people vaccinated. Better vaccines could include those that could keep people from catching the virus in the first place not just from getting seriously ill — such as a nasal spray vaccine. Or perhaps vaccines that provide longer protection or are administered in pill form, to make them more acceptable to the needle-averse.
"Particularly now when Congress is not allocating new funds for COVID response, we have to be especially judicious in how we spend our money and what would be most cost-effective," says Dr. Celine Gounder, a senior fellow at the Kaiser Family Foundation. "It's unclear whether updating the booster formulations and repeatedly boosting people is the most effective approach to controlling COVID at this stage."
Another concern some researchers have is that the FDA continues to rely on antibody levels to test vaccine efficacy.
"I think we need to raise the bar and require more evidence of clinical efficacy," says Dr. Eric Rubin, a professor of immunology and infectious diseases at Harvard who is also a member of the advisory committee. For instance, Rubin says the FDA should require proof the updated vaccines are actually reducing the risk of getting infected, getting sick, hospitalized and dying.
Others say updating the vaccines make sense to make sure people are as well-protected as possible while researchers continue to try to develop new vaccines.
"Even if you don't have a booster that matches 100% what's circulating, you will have a booster that matches 75% to 80% to 90% of what's circulating," says David Martinez, an immunologist at the University of North Carolina, Chapel Hill. "And that will be good enough. It would probably benefit most people."
The FDA looks ahead to endemic COVID
Some researchers think it's too soon to rely on annual boosters. COVID hasn't quite settled into a seasonal pattern like the flu, they note, and the SARS-CoV2 virus is changing more quickly than the flu virus. So people may need to be boosted more frequently, especially since protection against severe disease may only last about four to six months, they say.