STEVE INSKEEP, HOST:
Today, an independent advisory panel gives its judgment of a coronavirus vaccine. It's one of the final steps before the Moderna vaccine could receive emergency approval from the Food and Drug Administration and become the second vaccine available in the United States. So what are the questions that panel must answer? NPR science correspondent Joe Palca is with us. Joe, good morning.
JOE PALCA, BYLINE: Good morning, Steve.
INSKEEP: Who's giving their opinion today?
PALCA: Well, these are scientists with a variety of expertises. You've got vaccinologists, virologists, immunologists and statisticians who can vet the statistical analysis that the company has provided to FDA for the studies it's conducted. And while they'll discuss a lot of issues, at the end of the day, they'll be asked one straightforward question - do the known benefits of allowing the vaccine to be distributed during the COVID-19 pandemic outweigh the known risks?
INSKEEP: What evidence has the company provided?
PALCA: Well, the company's tested this vaccine in 30,000 volunteers. Half got the two shots of a placebo. Half got two shots of the real vaccine. And they compared to see which group got more cases of COVID. And the ones who were vaccinated were protected 94% of the time. The company also told the FDA about what are known as adverse events, illnesses that might be caused by the vaccine itself. Stacey Schultz-Cherry is a vaccine researcher at St. Jude Children's Research Hospital, and she says there didn't appear to be anything serious.
STACEY SCHULTZ-CHERRY: I went through some of the adverse events that were reported. Nothing jumped out at me.
INSKEEP: So she says, Joe, but don't some people feel lousy after taking this vaccine?
PALCA: Yes, there's definitely been reports of people with sore arms after the injection, fatigue, fever, swollen lymph nodes. But for the most part, these only lasted a day or two. And Schultz-Cherry says these reactions actually prove that the vaccine is working.
SCHULTZ-CHERRY: It doesn't mean that you're getting COVID. It doesn't mean that there's, you know, something wrong. It's just the nature of this vaccine.
PALCA: Still, there could be events that might not have been picked up by these studies. I mean, Moderna only studied tens of thousands of people, and there will be millions of people getting this vaccine if it becomes available, so other things might crop up.
INSKEEP: Yeah, some rare event that happens one in a million times. What kinds of rare events could we be talking about there?
PALCA: Well, you don't know for sure, but the people who got the Pfizer vaccine, some of them had this serious immune reaction called anaphylaxis. Then there were also known things that have happened. I mean, there are something called Bell's palsy, which is a facial paralysis. Both the Pfizer and Moderna vaccines had a few cases. The trouble is that that might be related to the vaccine, but it might not because people who don't get vaccines also get Bell's palsy. So it's hard to say they're connected.
INSKEEP: So all of these experts weigh all this evidence and decide if the benefits outweigh the risk. What happens after they vote?
PALCA: Right. So FDA decides whether to grant this thing called an emergency use authorization. The expectation is that they will grant that. Last week, approval came 16 hours after the committee voted. And the FDA has been working with the company for weeks, so they've got a lot of the documents and what have you worked out so that they'll be ready to go.
INSKEEP: Joe, can you explain one more thing to us? We're finding out there's more Pfizer vaccine available than people thought.
PALCA: Yeah, this is strange. The FDA says vaccine distributors are finding that many of the vials contain six or seven doses instead of the five that are supposed to be there, and the agency said, OK, you can go ahead and use those extra shots. And they're going to try and figure out what the company - what happened, why there's more shots in the vials.
INSKEEP: OK. It's like there's a bonus toy in the package. Joe, thank you very much.
PALCA: You're welcome.
INSKEEP: NPR science correspondent Joe Palca. Transcript provided by NPR, Copyright NPR.