MARY LOUISE KELLY, HOST:
Later this week, an independent group of experts that advises the FDA will meet virtually, and it should be lively. That is because the topic is whether to approve a third shot of Pfizer's COVID-19 vaccine for all Americans older than 16. This is a controversial question. President Biden says he wants boosters. Researchers are divided. Global health leaders say the vaccines that are available should go to billions of people around the world who remain unvaccinated. Joining us now is NPR's Joe Palca. Hey, Joe.
JOE PALCA, BYLINE: Hi there, Mary Louise.
KELLY: So what kind of evidence are we expecting Pfizer to present to make the case that they say a booster shot is necessary?
PALCA: Well, they've got a panoply of evidence. There's been some - excuse me - data from Israel that shows that the efficacy of the vaccine is waning because people who are getting sick there - this is in one study - were vaccinated six months or more ago, as opposed to people now - recently, they've not been getting sick. So the vaccine was working better if you got it more recently.
And there's a paper in today's New England Journal of Medicine that also has data from Israel that showed that boosters, which they've been giving out there, clearly lowered the risk of disease - both mild and severe disease.
And the company also has laboratory data, showing boosters send antibody levels to higher than what they were after completing the first round of vaccinations. And those antibodies is a good thing because they appear to be working against some of the more dangerous variants.
KELLY: So if there's all this data and if the U.S. has plenty of supply, what's the case against giving boosters?
PALCA: Well, as you mentioned at the top, there is this question of vaccine equity. I mean, there are billions of people around the world who could use a vaccine - just one. And we're talking about giving a third to a bunch of mostly healthy people. So that's a question.
The other is more of a scientific one, which is, yes, there are antibodies levels that are declining, but it's not quite clear - I mean, and the efficacy seems to be declining. But the antibody levels declining - it's not clear how that relates to protection. And while more people may be getting infected, the rate of severe disease and deaths doesn't seem to be climbing dramatically. Here's Marion Pepper. She's an immunologist at the University of Washington.
MARION PEPPER: I think we need data. I think we need to see, are people actually getting sicker? And I don't know that anyone has shown that really effectively.
PALCA: And it all goes back to this question of what the vaccine is for. Is it to prevent hospitalization and death? Or is it to prevent any disease at all? And the evidence still seems to show that it's doing a pretty good job at preventing hospitalization and death.
KELLY: Has the FDA tipped its hand? Any idea which way they're leaning in terms of whether to approve this Pfizer request?
PALCA: Well, I'm sure they're under a lot of pressure since the president has pretty much already said, yes, we're going to do it. But it's not entirely clear. The agency laid out some guidelines before, when they told companies, this is what we're going to expect from you if you think you're going to get a booster approved. And it seems as if Pfizer has met those. But there's still a question of whether the evidence is solid enough and whether or not there's - whether the FDA, in fact, set the bar high enough. So that's going to be the discussion when this advisory committee meets later this week.
KELLY: And real quick - we keep talking about Pfizer. What about Moderna? Do they think they're going to need a booster?
PALCA: Yep. Yep. They also see a decline in efficacy, and they think a booster will be needed as well.
KELLY: All righty. NPR's Joe Palca, thank you.
PALCA: You're welcome, Mary Louise.
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