美国国家公共电台 NPR--Experts question the FDA's COVID booster strategy ahead of autumn

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Experts question the FDA's COVID booster strategy ahead of autumn

Transcript¹

COVID vaccine² makers³ are developing new boosters for a fall campaign. But some experts question the FDA's decision to tell companies to make shots against the BA.4/5 subvariants.

STEVE INSKEEP, HOST:

When summer ends, we begin the third autumn of the pandemic. The virus spreads more in cooler weather, and many people have stopped taking precautions. But for those who do, the United States is preparing a fall vaccine booster campaign. NPR health correspondent Rob Stein joins us. Good morning.

ROB STEIN, BYLINE⁶: Good morning, Steve.

INSKEEP: So what's the idea here?

STEIN: Well, you know, Steve, this is all about trying to prevent yet another bad winter surge. The immunity⁷ that people got from getting vaccinated⁸ or infected will have faded even more by the time winter arrives. And the fear is lots of people could get really sick and die unless their immune systems get another good boost. So Moderna and Pfizer and BioNTech created a new generation of vaccines⁹ called bivalent vaccines that target both the original strain of the virus and omicron. But the virus is evolving so fast that new omicron subvariants have already replaced the original omicron that those vaccines target. So the FDA told the companies to reformulate the vaccines yet again to target the latest omicron subvariants called BA.4 and 5. But not everyone thinks that was necessarily the right call.

INSKEEP: Well, why not?

STEIN: Well, you know, ideally, we would try to match the vaccines to whatever version of the vaccine is actually infecting people. But some say we just don't have time at this point to reformulate and test a whole new set of vaccines because that would push the vaccine's availability back to around October or November at the earliest, which is cutting it really close.

INSKEEP: Yeah.

STEIN: So some say the FDA should go with the vaccines that target the original omicron, known as BA.1, since they look pretty good. And the companies have already started even making them, which means they could be available much sooner, by the end of the summer. It's kind of the bird-in-the-hand argument.

Here's Deepta Bhattacharya at The University of Arizona.

DEEPTA BHATTACHARYA: Are we trying to be too perfect and then costing us months as a result of that? You know, if we were starting over and all things were being equal and BA.1 and BA.4, 5 could be, you know, developed at equal pace, no question, BA.4, 5 is better. But the real question is, are we letting the perfect be the enemy of the good here?

STEIN: You know, in fact, the companies have now produced data indicating the vaccines that target the original omicron can also protect against BA.4 and 5. And who knows whether BA.4 and 5 will even still be the dominant¹⁰ variants⁵ by the fall. Another entirely¹¹ different variant⁴ or subvariant could have taken over by then. Another subvariant called BA.2.75 has already emerged in India. And the FDA would also have to rely more on studies involving mice instead of people to judge the boosters, which makes some people wonder, are we really there yet with this new mRNA technology?

INSKEEP: I'm just trying to keep track - BA.2.75, 4, 4, 7.

STEIN: I know.

INSKEEP: It's like pi. You could just go off into the universe.

STEIN: Exactly. Exactly.

INSKEEP: Are there other concerns?

STEIN: Yeah. You know, some question the wisdom of switching to vaccines that target omicron at all because, so far, the data FDA has gathered doesn't prove that they're dramatically better than the original vaccines. I talked about this with John Moore at Weill Cornell Medicine.

JOHN MOORE: You might as well consult a crystal ball or a Roman augur¹² if you're going to make decisions on that level. I think that the FDA under-analyzed and under-consulted in making a decision that really sounds good but is based on guesswork.

STEIN: Now, for its part, the FDA acknowledges that there's no way to predict the future. But officials say they have no choice but to try to match the vaccines as closely as possible to whatever strain's most likely to be posing a threat. I talked about this with Dr. Peter Marks at the FDA.

PETER MARKS: Because we don't have a crystal ball, we have to do our best using the science that we have in hand. And this allows us to hedge our bets.

STEIN: And Marks is leaving the door open to switching back to boosters that target the original omicron if that looks like the better option to protect people in the fall.

INSKEEP: That's NPR health correspondent Rob Stein. Rob, thanks so much.

STEIN: You bet, Steve.