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2 Coronavirus Vaccines Move To Final Testing Phase

AILSA CHANG, HOST:

Two companies announced today that they are beginning widespread testing of potential coronavirus vaccines. One comes from a collaboration between the National Institutes of Health and the U.S. biotech company Moderna. The other is from a collaboration between the pharmaceutical giant Pfizer and the German biotech company BioNTech. Each trial needs 30,000 volunteers. And here to tell us more is NPR science correspondent Joe Palca.

Hey, Joe.

JOE PALCA, BYLINE: Hello, Ailsa.

CHANG: All right, so not one but two vaccines moving into this big new phase of testing. Can you just tell us, how are these vaccines supposed to work?

PALCA: Well, they're actually - it's interesting. They're both what are called mRNA vaccines. It's a new approach to making a vaccine, where you inject someone with a little snippet of RNA. And that prompts their cells to make a protein. And that protein stimulates their immune system, which makes them able to fight off the coronavirus if they're exposed to it. I have to tell you, though, that there is no FDA-approved mRNA vaccine yet for anything, so this is a completely new technology.

CHANG: OK. Well, I'm wondering because these vaccines have been tested for months now, so what is different about this latest phase of testing?

PALCA: Well, the earliest phase of testing is just to make sure that the vaccines don't cause any horrible side effects that patients would or people would find completely intolerable. And they've passed that hurdle. They've also been tested to see if they generate any kind of immune response at all, but that's a laboratory test. Now the proof is, can it actually prevent people from getting infected if they're exposed to the coronavirus? And that's the reason they need so many people because they have to give people a reasonable chance of getting exposed so they can tell whether the vaccine is doing better than a placebo because they'll divide people in half. Some will get the vaccine. Some will get a placebo.

CHANG: OK. Well, we keep hearing, you know, usually it takes years to make a new vaccine, but these vaccines, obviously, seem to be moving on a much faster timeline. How has that even been possible?

PALCA: Well, the manufacturers and the government officials working on this are all saying, look; we're doing things a little differently now. Instead of doing things one - serially; one - first phase one, then phase two, then phase three and waiting till each one is done - we're sort of getting ready for everything altogether because we can shorten the time it takes to prepare if we take chances and say, well, we hope this works. And if it does, you can move forward. But in announcing the start of the trial for the NIH and Moderna vaccine, the head of the National Institutes of Health, Francis Collins, said in a teleconference this morning that that trial is part of Operation Warp Speed. And warp speed suggests something that's going really, really fast. But...

(SOUNDBITE OF ARCHIVED RECORDING)

FRANCIS COLLINS: Nothing is being done here to compromise the safety of this particular trial or others like it, nor will we compromise on an ultimate conclusion about whether the vaccine is effective.

PALCA: And what he means by that is some people have suggested if they're close to an answer but they're not really sure in October, then the White House might insist that it be called effective and take credit for it as a political coup just before the election. But they're saying - the scientists are saying, no, we're not going to let that happen.

CHANG: So how will we know if these vaccines truly do work?

PALCA: Well, it's going to take time. And as I said, there'll be two groups; a vaccine group and a placebo group. And what will happen is even though the participants won't know what they're getting, there will be a group of people who will keep their eye on the results. And they're called a data safety monitoring board. Their first job is to make sure the vaccine isn't making people sicker. But they'll also be looking out to see if they're seeing a difference between the number of people who get sick who get the vaccine - hopefully none - and the number of people who get sick who just get the placebo. So in a couple of months, we might begin to get answers to that.

CHANG: All right. That's NPR science correspondent Joe Palca.

Thanks, Joe.

PALCA: You're welcome. Transcript provided by NPR, Copyright NPR.