SACHA PFEIFFER, HOST:
Starting Monday, people flying to the United States from the United Kingdom will have to prove they are not infected with the coronavirus before they can board their flight. The Centers for Disease Control and Prevention instituted this requirement because a new and potentially more infectious strain of the virus is now circulating widely in the U.K. The CDC hopes this move will keep the strain out of the U.S.
Joining us now to talk about this development is NPR science correspondent Joe Palca. And, Joe, would you tell us whether screening airline passengers is likely to keep the new virus strain out of the U.S.?
JOE PALCA, BYLINE: Well, I mean, that's the hope. It's a way of stopping the virus from coming into the country. But there is a chance it's already here, in which case this is closing the barn door after the horse has left. So it's a step they can take. There's not a lot of other steps that are available.
PFEIFFER: And, Joe, a very basic science question - remind us why new strains of a virus show up.
PALCA: Well, viruses are changing all the time. I mean, every time a virus replicates inside of you, it has to pass on its genetic material. And every time it does that, errors crop up. And most of the time, these errors don't make any difference in the way the virus acts when it gets inside you. But sometimes there are changes in a piece of the virus that could actually make a difference, and that seems to be what happened here. There's a change in a part of the virus that codes for the spike protein, which is the protein that allows the virus to enter cells, and so that's why it's concerning.
PFEIFFER: Do scientists know yet how big of a problem this new strain is likely to pose?
PALCA: No. I mean, it appears to be more infectious. It doesn't appear to be more dangerous in the sense it doesn't seem to be making people sicker. But if this apparent infectiousness holds up, it's going to reinforce the message of mask-wearing, hand-washing and keeping distance because those are the only things we have, in addition to the vaccine, that will prevent people from getting it.
PFEIFFER: But meanwhile, the COVID-19 vaccine is being administered. People are getting shots. So will the vaccines being rolled out now protect people from this new strain?
PALCA: Well, again, it's unclear. I've seen people from BioNTech say, yes, it'll protect. But they also say, in order to say for sure, we're going to need to do some testing. So I think it's fingers crossed at the moment. I mean, the good news is that vaccines like the one Moderna and Pfizer have made are relatively easy to tweak. And so if it turns out to be necessary, they could actually change the vaccine so it works better against the new strain.
PFEIFFER: In terms of where we are on the vaccine landscape, which ones are furthest along in development and when might they become available - the ones that are still being researched and working on in labs?
PALCA: Yeah, there's quite a few. The ones that are likely to come into this country are University of Oxford-AstraZeneca vaccine. That's being tested in this country now. Another vaccine is one made by Johnson & Johnson. That's enrolled a trial of 40,000 people, and they expect to read out result, or a preliminary result, next month.
PFEIFFER: And, Joe, would that just be one shot instead of two, the J&J vaccine?
PALCA: Yes, that's right. And the Novavax vaccine - that's another kind of vaccine that has completed 15,000 people enrollment in the U.K., and they're also enrolling people in this country. And the good news about these three different vaccines is they act in different ways slightly from Moderna and Pfizer. So it may turn out that these are easier to administer for some people, work better for some people. But they're definitely different, and probably that's a good thing 'cause it gives health officials a choice of which vaccine to use.
PFEIFFER: NPR science correspondent Joe Palca, thank you for the update.
PALCA: You're welcome.
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