The Food and Drug Administration is considering a major shift in the nation's COVID-19 vaccine strategy.

The goal is to simplify vaccination against COVID and perhaps adopt an approach similar to what is used for the flu vaccine, with annual updates to match whatever strain of the virus is circulating. This is according to a federal official who spoke under the condition of anonymity because they were not authorized to speak publicly.

NPR reported the proposed shift early Monday morning, and later Monday the FDA outlined it publicly in a set of documents released in advance of a meeting Thursday of the agency's Vaccine and Related Biological Products Advisory Committee (VRBPAC). The committee will vote on the agency's proposal.

Currently, people who want to be fully vaccinated against COVID have to first get their primary vaccinations — two shots of the original vaccine spaced weeks apart. That's followed at least two months later by a booster, currently the bivalent shot that's tailored to protect against omicron.

Under the new approach, most people would be advised to simply get whatever the latest version of the vaccine is annually each fall like the flu vaccine. They wouldn't have to worry about how many shots they've already gotten and which one they got when. Those who still need to receive two doses initially, such as young children and older people, would use the same formulation for all three shots.

Vaccine makers would update the annual shot through a process that would begin each spring to try a match the vaccine as closely as possible to whatever variant will likely be dominant in the coming winter. That's how the flu vaccine is formulated each year.

"FDA anticipates conducting an assessment of SARS-CoV-2 strains at least annually and to engage VRBPAC in about early June of each year regarding strain selection for the fall season," the FDA wrote in its briefing document, adding that updated vaccines would be readied for use by September each year.

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.

"We're going to be reaching that pretty soon with the early adopters of the bivalent boosters, like myself," says Dr. Peter Hotez, co-director of the Center for Vaccine Development at Texas Children's Hospital and dean of the National School of Tropical Medicine at Baylor College of Medicine. "I don't know if an annual strategy is going to cut it."

The FDA's plan comes as COVID appears to be moving toward becoming an endemic disease. That doesn't mean it's going away or it's not a threat anymore. The disease will continue to be a threat for the foreseeable future, making many people sick and even potentially killing hundreds a day, making it a major public health problem and a leading cause of death, health experts say.

But unless some more dangerous version of the virus suddenly emerges, the world might finally be settling into a more predictable co-existence with the virus. The federal official NPR spoke to says the goal of the new vaccine strategy is to make the vaccines, which are the major weapon for protecting ourselves, simpler and hopefully therefore more appealing. The latest boosters have found very few takers.

The thinking is that at this point in the pandemic the overwhelming majority of people have a significant levels of immunity, either from having gotten vaccinated and boosted, or infected one of more times, or both. And while that immunity appears to protect most people from severe disease, that protection does appear to fade with time.

The FDA is also considering making the shots interchangeable. That way people wouldn't have to worry which brand they're getting. Again, the change is aimed at making COVID shots more like the flu shots. People don't typically worry about the brand of the flu vaccine they receive.

The vaccine would still be administered at different doses for different ages. And very young children and older people would still get two shots each year, much like the flu vaccine.

If the FDA advisory committee endorses the approach Thursday, the FDA would work with the vaccine companies and Centers for Disease Control and Prevention to finalize the details. And the FDA advisers would meet again in the spring to pick the specific strain or strains of the virus the new shots should target.