ARI SHAPIRO, HOST:
The CDC and the FDA both say if you are fully vaccinated against COVID-19, you do not need a booster shot to be protected from disease. That's true even for new variants of the virus turning up in the U.S. Despite that, the pharmaceutical company Pfizer announced it would be seeking regulatory authorization for a third shot of its COVID-19 vaccine. And the company said it was developing a new vaccine specifically targeting the Delta variant. Joining us now is NPR science correspondent Joe Palca. Hi, Joe.
JOE PALCA, BYLINE: Hi, Ari.
SHAPIRO: Help us sort this out. What reason is Pfizer giving for asking the FDA to authorize a third shot?
PALCA: Well, for months now, Pfizer CEO Albert Bourla has been saying he thinks a booster will be necessary, and it may be at some point. But the thing is that since he's been saying that, some scientists have been disagreeing and saying there's evidence that it might not be necessary. So it's an open question. But the COVID-19 vaccine is a big, successful product for Pfizer, and, of course, they'd like to sell as many doses as they can, so they may see the evidence tilting in favor of a booster, where others might not.
SHAPIRO: So there's an economic consideration here. But scientists are studying boosters, right?
PALCA: Oh, yeah. There's a good reason to think it may be necessary. And companies are doing their own trials. But there's another interesting study that's testing a mix-and-match strategy where you might get a booster of the Johnson & Johnson vaccine after initially getting the Pfizer vaccine. Kirsten Lyke at the University of Maryland Center for Vaccine Development and Global Health is one of the lead investigators of this study. And she says the advantage is that it's being paid for by the federal government's National Institutes of Health.
KIRSTEN LYKE: NIH can approach this in an unbiased manner with no, you know, dog in the race, per se.
PALCA: In other words, there's no business incentive to see the results in a particular way.
SHAPIRO: Is there an advantage to this mix-and-match strategy?
PALCA: Well, it's not certain. But the interesting thing is that the Johnson & Johnson vaccine uses a different technology from the Pfizer and Moderna vaccines. And there's some suggestion from other research and other vaccines that different kinds of vaccines can provoke a more potent immune response. So there's reason to think that mixing and matching may give you a better protection. Kirsten Lyke says the goal of her project is to answer two main questions about getting a booster.
LYKE: Is it safe? And what is the immune response that's generated to these boosters?
LYKE: Because if we're going to give a mass booster, let's figure out which one is the most efficient to give.
PALCA: Do you know whether a booster is necessary at this point?
LYKE: Yeah, I don't think anyone knows.
PALCA: And it may turn out that some people need a booster sooner than other - for example, people in nursing homes or frontline health care workers. And it's also possible that people with compromised immune systems might need something sooner than others. So - but this is the point Lyke makes - is that now is the time to find out what works so that if the time does come when we need a booster, we'll be ready to go with the best one that's available.
SHAPIRO: All right. So more information to come as scientists learn more. One other question - the CDC has updated its guidance on protecting K-12 students against COVID when they go back to school in the fall. What's the agency saying?
PALCA: Well, the first thing they're saying is they're acknowledging the importance of in-person learning. So they do think it's important for kids to get back in the classroom. The next thing they're saying is that everyone should get vaccinated. Now, the vaccines are only approved for children older than 12, but it may be younger than that by the end of the year. They're also saying anyone older than 2 who's not vaccinated should wear a mask. They're saying they should maintain distancing of three feet where possible, and anyone who is sick should stay home.
SHAPIRO: NPR science correspondent Joe Palca. Thank you.
PALCA: You're very welcome.
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