The FDA may authorize a second COVID-19 booster for adults 50 and older, reports say. But not all experts agree.

Everyone 50 and older could soon be eligible for an additional COVID-19 vaccine at least four months after their booster shot.

According to multiple reports, the Food and Drug Administration is likely to approve that extra shot as soon as Tuesday, as a hedge against a surge of infections – either from the BA.2 variant or another to come. 

Some health experts questioned the focus on a fourth dose when many people still haven't had earlier doses, when cases are near historic lows and before there's solid data supporting the need for another shot and for whom. 

"There are people who will benefit from a fourth shot, but the real gap is getting first, second and third shots to people over 65," said Dr. Tom Frieden, a former director of the Centers for Disease Control and Prevention. "That really is the bigger risk right now."

The oldest Americans, who are at high risk of being hospitalized and dying from COVID-19, should be authorized for another shot, experts told USA TODAY, but there isn't data to suggest a benefit from a fourth shot for an otherwise healthy younger person.

"Where's the evidence?" asked Dr. Paul Offit, who directs the Vaccine Education Center at Children's Hospital of Philadelphia.

Information from other countries shows a clear benefit to a fourth dose for people who are immunocompromised or over 70. Both groups may have trouble making the immune soldiers that protect against serious disease, said Offit, a member of the FDA's vaccine advisory panel.

Americans with immunocompromising conditions, such as organ transplant recipients and active cancer patients, are authorized to get a fourth dose in the USA.

Offit worries there may be unintended consequences to repeated boosters for healthy people, along with diminishing returns.

The first two doses have been extremely effective in protecting otherwise healthy people from becoming severely ill from COVID-19, he said, raising questions about the need for repeated boosters.

"You may get a cold, even though you've been vaccinated," he said. "We're going to have to live with that."

The New York Times reported late last week that the FDA would authorize a fourth shot this week to deal with a possible spike in cases from the BA.2 variant. USA TODAY could not independently confirm the report. 

The CDC may stop short of strongly recommending a booster for those over 50, as it did with the original doses and the initial booster, according to The Washington Post.

The BA.2 variant, which dominates the world, is causing a jump in cases in many countries. Although cases have turned slightly upward in a number of states after a precipitous decline in recent weeks, it's not clear whether BA.2 will lead to a dramatic spike in the USA.

Because vaccines prevent infection for only a few months – while apparently preventing severe disease for longer – now may not be the time to offer fourth doses, several experts said.

"If one was going to get a fourth shot, one would do it when one had some confidence it was needed," said Dr. Phil Krause, an independent consultant who resigned last year as the deputy director of the FDA's Office of Vaccines Research and Review.

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“It’s highly likely we’ll have another wave in the upcoming months,” said Albert Ko, an infectious disease physician and epidemiologist at the Yale School of Public Health. “It takes time to get data. It takes time to get evidence.”

The risks of having little data outweigh the benefits of having lifesaving vaccines available before a potential surge, he said.

Dr. Megan Ranney, an emergency room physician at Rhode Island Hospital and public health expert at the Alpert Medical School of Brown University, said she sees the approval as an "insurance policy," so boosters will be available when needed.

For someone who's otherwise healthy, "I wouldn't rush out to get a booster today," Ranney said. "I would be waiting and seeing."

Getting a booster too early, she said, means its protectiveness might fade by the time a surge in infections arrived. 

It makes sense to keep the boosters on a shelf for now, holding off on delivering them to all but the most vulnerable, said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University School of Medicine in Nashville, Tennessee.

"I'm of the inclination to wait and see," he said. "Cock the gun, but don't shoot it."

Most of the data on fourth shots comes from studies in Israel, which offered extra boosters late last year as the omicron variant surged.

One study suggests that a fourth shot can substantially reduce the number of deaths from COVID-19 in people above 60 and particularly those over 80.

But the Israeli data showed a reduction in severe disease only among those at highest risk – raising questions about whether the general population would benefit from a fourth shot, Krause said.

"There's only a very small group that stands to benefit substantially from this fourth dose," he said.

To decide whether to get fourth dose, people should ask themselves whether they're at high risk for a severe outcome, Krause said. If they're not, they probably wouldn't benefit from another booster, he said.

Congress gas declined to support additional funding for the president’s COVID-19 prevention measures, so some experts argued limited funds should not be spent on additional boosters without data to support them.

Long-term data is lacking, so it's not clear how long the benefit of a fourth dose might last. 

Ko said so many Americans are at high risk for severe disease because of underlying health conditions that it makes sense to offer boosters to everyone 50 and over.

Making a second booster available to everyone in that group would increase access to underserved communities, where people are more likely to have comorbidities that put them at risk for severe outcomes of COVID-19.

“We have to think about who has been hit the hardest, and many are underserved populations with underlying poor health status in inner cities,” he said. “So tacking on that extra (over 50) group makes a lot of sense to me.”

Most of the experts said they wished the decision-making process had gone through scientific advisory committees, which hold public meetings, rather than apparently happening behind closed doors. 

"These recommendations should be coming from the CDC's advisory committee," said Schaffner, who sits on that body, "not from Washington."

Contact Rodriguez at adrodriguez@usatoday.com and Weintraub at kweintraub@usatoday.com 

Health and patient safety coverage at USA TODAY is made possible in part by a grant from the Masimo Foundation for Ethics, Innovation and Competition in Healthcare. The Masimo Foundation does not provide editorial input.