AUDIE CORNISH, HOST:
The Food and Drug Administration could greenlight Pfizer's COVID-19 vaccine for emergency use as soon as this evening. Testing shows the shot appears to be safe. But it does come with side effects, and those could complicate efforts to vaccinate health care workers. Joining us to talk about that and related vaccine subjects is NPR science correspondent Richard Harris. Welcome, Richard.
RICHARD HARRIS, BYLINE: Hi, Audie.
CORNISH: It will be many months before most of us will be able to line up for the vaccine. What should the first recipients - and this includes health care workers - what should they expect from it?
HARRIS: Well, about 20,000 volunteers have already gotten the needed two doses of the vaccine. And the majority did report some side effects - that includes soreness at the site of injection, headache, achy joints and the occasional fever. Doctors say they are more pronounced than what you get with a typical flu vaccine, but they're on a par with the shingles vaccine. That means the shot can lay you low for a day or so. And Dr. Rochelle Walensky at Harvard says that adds a wrinkle for inoculating key health care workers.
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ROCHELLE WALENSKY: We certainly can't be vaccinating the entire intensive care unit if we think, within the week, 30% of them are going to have symptoms that are going to have to make them stay home.
HARRIS: Walensky, by the way, has been nominated to run the Centers for Disease Control and Prevention come January.
CORNISH: What concern is there that these side effects will possibly discourage people from taking the vaccine?
HARRIS: Well, that is a potential complication for sure. Here's Dr. Walensky again speaking in a webinar.
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WALENSKY: Fortunately, they happen more often with the second shot than the first because I think we'd really get a hard time - have a hard time having people come back if it happened with the first.
HARRIS: And of course, in exchange for that nuisance, you do get protected from a deadly disease.
CORNISH: But can we just briefly talk more about the serious reactions, like the two cases reported earlier this week in Britain?
HARRIS: Sure. Those severe allergic reactions are a well-known side effect of vaccines. They didn't show up in the huge clinical trial of the Pfizer vaccine because people known to have severe allergic reactions were not allowed to participate. But Dr. Paul Offit, a vaccine expert at Children's Hospital of Philadelphia, says we shouldn't get overly worked up about this known risk of vaccines.
PAUL OFFIT: What we should do is what we've always been doing, which is be careful. And so for that reason, you are asked after you've gotten a vaccine or your child's gotten a vaccine to hang around for about 15 minutes just in case that's a problem.
HARRIS: And if it is, the nurse or doctor can give you a shot of epinephrine, which is a drug that's used to treat strong allergic reactions.
CORNISH: Some other vaccine-related news I want to get into - today, there was a different drug company that announced that its experimental vaccine isn't working quite as well as expected. What have you learned?
HARRIS: Right. Sanofi is working with a partner, GSK, on a vaccine that's still fairly early on in human studies. The companies reported that the vaccine doesn't stimulate as strong an immune reaction as they'd hoped in people over 50 years old. So they're reformulating it to see if they can get it to work better.
CORNISH: And that setback, could it delay vaccination plans in the U.S.?
HARRIS: Well, that depends on successes elsewhere. Moderna's vaccine is likely to get the nod from the FDA as soon as next week. Johnson & Johnson could have results from its big vaccine study next month. And there's AstraZeneca's vaccine, as well as one from Novavax, both in the works. So public health officials have committed to a lot of options as a way of hedging their bets.
CORNISH: That's NPR's science correspondent Richard Harris. Thanks so much.
HARRIS: Any time. Transcript provided by NPR, Copyright NPR.
