ARI SHAPIRO, HOST:
The Food and Drug Administration has given emergency use authorization to the drugmaker Pfizer for its new antiviral COVID-19 therapy. The new drug could be urgently needed because so far, it looks to be effective against the omicron variant that is spreading quickly across the U.S. NPR science correspondent Joe Palca is here with the latest. Hi, Joe.
JOE PALCA, BYLINE: Hey, Ari.
SHAPIRO: What's this new drug and how does it work?
PALCA: Well, the drug is called Paxlovid. It's what's called a protease inhibitor. It blocks a key enzyme inside the coronavirus called protease that the virus needs to grow, once it gets inside someone who's infected. You take a Paxlovid twice a day along with - for five days, along with a drug called ritonavir that helps it work. And you start taking the drug as soon as possible after symptoms appear. The sooner the better, but definitely within five days of detecting symptoms.
SHAPIRO: How well does it work against COVID-19?
PALCA: Well, Pfizer conducted a placebo-controlled study - that's the best kind - and in about 2,200 people at high risk for developing severe COVID. And the drug reduced the risk of hospitalization or death to close to 90%, which is very good. But I want to point out that most people in the study did not get sick enough to need hospitalization, so it's not as if you're doomed if you get sick and get infected. But of the people who did get sick, the drugs especially - the drug worked extremely well in preventing them - keeping them out of the hospital and keeping them from dying.
SHAPIRO: The omicron variant arose so quickly, it doesn't seem like it's been around long enough for the new drug to be tested on it. Why are experts confident it will work against omicron?
PALCA: Well, the interesting thing is that, yes, the omicron has a lot of mutations in it, but most of the mutations are in this thing called the spike protein, which is the protein that allows the virus to enter cells. It does not have a lot of mutations in the protease enzyme protein. And so it's - they think - and from lab tests and assays that they do inside a laboratory, they think that this drug will continue to work against that protease, even - and it's the same one that's in delta and the original strains and alpha and all the others. So it should work against the omicron one as well.
SHAPIRO: And then let's talk about supply. People have been struggling to get tests. They've been struggling to get booster shots. Are they now going to be struggling to get Paxlovid if they need it?
PALCA: Yeah, well, unfortunately, yes. That is going to be the case. There will be some supply fairly soon, but that supply will be limited. Mike McDermott is president of Pfizer Global Supply.
MIKE MCDERMOTT: We actually already have tens of thousands of packs in the U.S. positioned at our Memphis, Tenn., distribution center.
PALCA: And McDermott says he expects the company will be able to produce 180,000 treatment courses by the end of this year. But he says those numbers should go up rapidly.
MCDERMOTT: By the middle of next year, 30 million; and full year next year, 80 million.
PALCA: Now, who gets those doses is up to the U.S. government, at least initially, because the government has bought 10 million doses of the drug, which they'll distribute throughout the country.
SHAPIRO: And just briefly, there's another one waiting in the wings, right?
PALCA: Yes, there is another drug from Merck that might be getting an emergency use authorization. It doesn't seem to work quite as well, but it should be useful because it too seems to work against the omicron variant.
SHAPIRO: NPR's Joe Palca, thank you.
PALCA: You're welcome. Transcript provided by NPR, Copyright NPR.
