RACHEL MARTIN, HOST:
There's a new vaccine, and it's proving effective in preventing COVID-19 and even some of the new variants of the virus. This one is made by the U.S. biotech firm Novavax. The vaccine showed an efficacy rate of 89.3%. But scientists are most excited about the fact that this new addition to the vaccine roster is resilient to a U.K. variant spreading around the world. One big caveat, though - early studies show it is not as effective against the South African strain, a strain that has now made its way to the U.S. Joining me now, NPR science correspondent Joe Palca. Good morning, Joe.
JOE PALCA, BYLINE: Morning, Rachel.
MARTIN: What more did these early studies show about this vaccine?
PALCA: Well, there were two - one that was done in South Africa, one in the United Kingdom. And we'll start with the U.K. one. That had 15,000 volunteers. And, as you said, the overall efficacy rate was 89.3 89.6 - something close to that anyway - with slightly better against the original strain. But the good news was it was only a little bit slightly worse against the strain that was circulating in in the U.K. So it seems to be working pretty well about that. Now, these are interim results, so they have to be taken with a grain of salt. But the people I spoke with were impressed. For example, here's John Grabenstein. He's editor for the Immunization Action Coalition.
JOHN GRABENSTEIN: It's great. It's the fourth vaccine candidate to report phase three efficacy data. It's the third to be above 85 percent and the first of - you know, of this vaccine type.
MARTIN: What does that mean, Joe? What vaccine type?
PALCA: Well, this is called a protein subunit vaccine. It's a different - it uses two - it uses little pieces of the virus to stimulate the immune system. It's not the virus itself. And it's a technology that's been used successfully to make vaccines in the past. And it's better understood than the vaccines made by Moderna and Pfizer, which are a newer kind of vaccine called mRNA vaccine. And they don't have the same track record.
MARTIN: All right. So what about that that study out of South Africa? What did that one say?
PALCA: Well, this was a smaller study, 4,400 volunteers. And John Grabenstein said this was largely positive, too.
GRABENSTEIN: The only caveat - and I'm sure everybody's noting this - is what is the South African part of the data mean? And it's - you know, that's still a glass more than half full.
PALCA: And so in this study, the efficacy was closer to 60 or even less than that - 60%. And it seems that one of the reasons for that is that the variant of the virus that's circulating in South Africa is the one that has scientists worried. And that seems to be causing the lower efficacy.
MARTIN: And this, of course, is the variant that was discovered yesterday in South Carolina - two people, right?
PALCA: Yes, not good. Exactly. And the Novavax - so the Novavax vaccine was designed on the characteristics of the original strain of the virus. And the South African variant has different characteristics. So it seems that vaccine didn't do as well. It did pretty well. I mean, 60% isn't chopped liver, but that's what Grabenstein meant when he said the glass was more than half full. The other troubling detail from the South African study is that it seemed to show that people who had previously been infected with the original version of the coronavirus were not protected from this new variant, although the numbers in the study were small, and it's still not clear whether they got as sick after being infected again with this new variant.
MARTIN: So, I mean, Joe, can they just change the vaccine? I mean, can they adjust it to work against the new variant?
PALCA: Yeah, that's one of the good things about these newer vaccine technologies. They're easier to tinker with. And they are already coming up with new versions of the vaccine that they think they'll be able to test in the clinic not before too very long.
MARTIN: Can we see it in the U.S. soon?
PALCA: Maybe. Novavax says it's talking with the U.S. It's probably going to go to the U.K. regulators first with the data it's got. And I have to say there's another vaccine coming along, this one from Johnson & Johnson. And we're expecting to hear results from studies of that vaccine very soon.
MARTIN: NPR's Joe Palca, thank you.
PALCA: You're very welcome. Transcript provided by NPR, Copyright NPR.
