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3rd Coronavirus Vaccine Candidate Reported To Be Effective

AUDIE CORNISH, HOST:

For the third Monday in a row, we have good news about a coronavirus vaccine. Today the pharmaceutical company AstraZeneca and its partner, the University of Oxford, announced that their vaccine was 70% effective in preventing COVID-19. This vaccine uses a different technology from the ones made by Pfizer and Moderna that have already been shown to be effective. Joining me now is NPR science correspondent Joe Palca to talk about the news. Joe, what is this technology? How is it different?

JOE PALCA, BYLINE: Well, Audie, the Pfizer-BioNTech and Moderna vaccines are what's called MRNA vaccines. They work by injecting a tiny snippet of the genetic material of a coronavirus directly into someone's body, and that material contains instructions for a protein that can prompt someone's immune system to make an immune response to the coronavirus. So are you with me so far?

CORNISH: Yes, that's sort of vaccine as we know it.

PALCA: Well, it's a little different, but this one is even different still because the AstraZeneca-Oxford vaccine also contains genetic material from the coronavirus. But instead of injecting it directly into someone, it's carried into someone's body using what's called a viral vector. Now, this has certain advantages, not least that it's cheaper and easier to make this vaccine. So in the study we're hearing about today, one group of people got two doses of the vaccine, and another group got two shots also, but those injections didn't contain the experimental COVID vaccine. Andrew Pollard is head of the Oxford Vaccine Group, and he says the vaccine worked pretty darn well.

ANDREW POLLARD: We've got a vaccine which is highly effective. It prevents severe disease and hospitalization. And intriguingly, in the results, we do have a subgroup who got a half-dose as the first dose and then a full dose of the second dose where we saw 90% protection.

CORNISH: He said intriguingly. And how does that work - right? - half a dose being better than a full dose?

PALCA: Yeah, the two - the full doses are, all the trials showed, 70% effective. This is 90. Well, it's a bit of a puzzle. And Sarah Gilbert is a professor of vaccinology at the University of Oxford. She developed the vaccine, and she says puzzles are fine with her.

SARAH GILBERT: We're a group of academics, and we're delighted to have something more academic to study on this. And it could be that by giving a small amount of the vaccine to start with and following up with a big amount, that's a better way of kicking the immune system into action and giving us the strongest immune response and the most effective immune response - but more work to do on that.

PALCA: Yeah, sounds like more work to do on that. And it seems they only came up with this result by chance when researchers realized they had underestimated the potency of the first injections in one of the groups of volunteers.

CORNISH: What happens next in this process?

PALCA: Well, AstraZeneca says they will take this data that they've gathered - these data into the U.K. and European regulatory agencies and discuss getting approval for some sort of - you know, discuss with them some sort of approval, provisional approval. And they'll also talk with the U.S. Food and Drug Administration to see if this data will satisfy them for a emergency use authorization. And they'll also be talking to the FDA to see if they can modify the vaccine study that's going on in this country where they've already enrolled 10,000 volunteers in order to switch to that same regimen where you get a half-dose and then a full dose.

CORNISH: And the storage - how is it different?

PALCA: Well, you might remember that the Pfizer vaccine used - had to have ultracold freezers, and this one does not. It doesn't even need a freezer. It can be stored safely at normal refrigerator temperatures. And that makes it easier to distribute globally, which AstraZeneca says it's committed to doing. And they're also planning to keep the cost down to about $3 a dose, make it more available in low-resource countries.

CORNISH: That's NPR science correspondent Joe Palca.

Thank you.

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

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