SCOTT SIMON, HOST:
An independent panel of experts is complicating the Biden administration's plan to offer most adults in the U.S. a booster shot of the COVID-19 vaccine. On Friday, the panel rejected a request by Pfizer to provide a booster shot for its vaccine to people 16 and older. Instead, they endorsed a plan to offer the shot only to those who are high risk and 65 and older. The FDA doesn't have to go along with this panel's advice. They generally do. NPR's Joe Palca is here to talk about it with us. Joe, thanks so much for being with us.
JOE PALCA, BYLINE: You're welcome, Scott.
SIMON: Let's back up a bit to the request that Pfizer was making. What did they think the argument was for a third dose of the vaccine?
PALCA: Well, they have laboratory data showing that if you take blood from people who have been fully vaccinated, over time, the antibodies in that blood starts to go down. And at some level, they're not protective anymore, but nobody knows what that level is. And so - and they found that by giving people a booster, they can boost the levels back up. Plus, there is extensive evidence from Israel that efficacy may be waning. The longer it's been since you got your shot, the more likely it is that you'll get a breakthrough infection. Although many of these breakthrough cases were mild, some were serious.
And there's also evidence now starting to come from Israel that a booster there can help. In fact, Israel is offering the third dose to virtually everyone in the country to stem a fourth wave of COVID that's been washing over the country. But clearly, the expert panel, known as the Vaccine and Related Biological Products Advisory Committee, or VRBPAC to the FDA, wasn't convinced the Israeli experience proved a third dose was for everyone. Paul Offit of the Children's Hospital of Philadelphia is a member of VRBPAC, and he spoke after the meeting.
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PAUL OFFIT: We made the decision not to follow Israel's lead, which is to just give a third dose, period, to make it, you know, a three-dose vaccine now. Rather, we're choosing to make it a booster for those at - you know, who are over 65, who are at high risk for health reasons or who are at high risk of acquiring the disease because of their occupation.
SIMON: Joe, what was the panel's reason for that? If the vaccine's efficacy seems to be waning, why not give a booster to everyone?
PALCA: Well, the evidence was stronger for older people and people at higher risk, and there's not a lot of experience with giving a booster. The safety data from Israel, for example, is only a month or so old. So you want to be careful about giving a third dose or any dose of a vaccine until you know that the benefits are going to outweigh any potential risks.
SIMON: So where does this all go now?
PALCA: Well, as Offit said, the panel made a recommendation to the FDA. The FDA has to decide whether to accept it or not. And then there's another advisory committee that's going to meet this week, Wednesday and Thursday. This is the Advisory Committee on Immunization Practices that advises the CDC. And they'll take a look at what the FDA's done and make their own decision about whether to endorse that and who they think should get vaccinated with a third dose.
SIMON: The FDA recommendation was for Pfizer. What about Moderna or Johnson & Johnson?
PALCA: Well, right now, this is only for people who've had the Pfizer vaccine. I'm sure at some point, CDC - FDA and CDC are going to start thinking about this thing called mix and match, where you start with one vaccine, and you maybe go to another. Or maybe it's people are going to get Pfizer and then Moderna. But at the moment, it's one - it's just Pfizer. Pfizer is the only one that's been up for review so far.
SIMON: NPR's Joe Palca, thanks so much.
PALCA: You're welcome. Transcript provided by NPR, Copyright NPR.