RACHEL MARTIN, HOST:
There are some promising developments in the race to find a coronavirus vaccine. The results could now mean that some 30,000 American volunteers will take part in a larger study. NPR science correspondent Richard Harris is following this and joins us now. Good morning, Richard.
RICHARD HARRIS, BYLINE: Good morning.
MARTIN: So there are two vaccines of interest here. Tell us about them.
HARRIS: Right. One is being developed by scientists in Wuhan, China, which - that one involved more than 500 volunteers. The other is out of Oxford University. And that one recruited more than 1,000 people for their preliminary tests. And the medical journal The Lancet published the latest results from both of those yesterday. I talked to Naor Bar-Zeev at Johns Hopkins University, who had a chance to review those papers in detail.
NAOR BAR-ZEEV: So far, everything we've seen has been encouraging. And most importantly of all, there have not been any severe - any serious, I should say - adverse events.
HARRIS: Some people did get the kind of reaction you can get from a vaccine - a fever or fatigue or pain at the site of the injection. But Bar-Zeev says those are to be expected.
MARTIN: OK. And he said everything we've seen has been encouraging. Does that mean they work?
HARRIS: Well, they are encouraging but not definitive. Let's put it that way.
HARRIS: One hopeful sign is that most of the people who got the experimental vaccine developed antibodies against the coronavirus. And those antibodies actually neutralized the virus, at least in the lab. Bar-Zeev was also encouraged to see that people's immune systems also revved up to produce custom cells called T cells that targeted the coronavirus.
BAR-ZEEV: And that may turn out to be really critically important. We don't quite know enough, really, about coronavirus immunity. But it may turn out that that's a really important part of protection against the coronavirus, particularly in terms of the longevity of the immune response.
MARTIN: Yeah, you know, it's really important to have an immune response that will last for a reasonable period of time, say at least a year. And that is not assured. Some people have fleeting immune responses to related coronaviruses. But there are, like, dozens and dozens of vaccines in the works, aren't there, Richard? I mean, can you put these findings for these two vaccines in that broader context?
HARRIS: Right. There are tons of them in the works for sure. And these two, I would say, are at the head of the pack, at least at the moment. They've been tested on more people than, say, the Moderna vaccine, which is a leading candidate here in the United States. But, you know, this is new scientific territory. So the worry is any potential vaccine candidate could falter along the way. I talked to Adrian Hill at the University of Oxford via Skype and asked what could, at least hypothetically, go wrong with the vaccine his team is developing.
ADRIAN HILL: What could go wrong is that this is an unusual virus where you need an awful lot of antibody to protect, and the levels that we're getting, even though they look good to us, may not be high enough to stop every last virus infecting cells.
HARRIS: He also worries about potential snags in mass production of the vaccine, which would be needed if it works, of course. And we won't know if it works until it's been tried out in tens of thousands of people who are at risk for getting infected to see if the shot actually lowers their risk. These tests include this - could - one of them, actually, could be rolled out in the United States, done by Oxford's commercial partner AstraZeneca.
MARTIN: What's the timeline that we're looking at here, Richard, as this moves forward?
HARRIS: Well, Hill says we could have results in October or maybe even earlier. Manufacturers are already thinking about how to ramp up production to make 2 billion doses of this vaccine available within a year.
HILL: Two billion doses is an aspiration. I hope we can do that. We're not at all sure we can. But even if we succeeded with AstraZeneca in doing that, there are still billions of people who would be left without a vaccine over the next few years.
HARRIS: So it's good that there are a lot of companies pressing ahead using a variety of strategies to produce a coronavirus vaccine. And, of course, even if, you know, this one does work, there's still room for others, a need for others, as well. So...
HARRIS: So more than one would be better, for sure.
MARTIN: NPR's Richard Harris, thank you.
HARRIS: Sure. Transcript provided by NPR, Copyright NPR.