SCOTT SIMON, HOST:
The United States has seen another grim mark in this pandemic. More than 700,000 people have died. But there might be some encouraging news on the way, as well. Two companies, Merck and Ridgeback Biotherapeutics, are working on an antiviral drug that seems to reduce the risk of hospitalization or death by half for COVID patients. Companies say that they will soon ask the U.S. Food and Drug Administration for authorization to distribute the drug. NPR's science correspondent Joe Palca joins us. Joe, thanks so much for being with us.
JOE PALCA, BYLINE: You're welcome, Scott.
SIMON: And first, of course, we want to just acknowledge the terrible death toll, 700,000 people. But that being understood, we may be in a different phase of the pandemic because of scientific advancements. So please tell us more about this drug, what it does and how it works.
PALCA: Well, it's what's known as an antiviral drug. It's got the name molnupiravir which - and it blocks replication of the virus. And in a study of 775 volunteers with mild to moderate COVID disease, it reduced the risk of hospitalization or death by 50%, from 14% down to 7%.
SIMON: The - of course, there are already drugs out there for the treatment of COVID-19. How is this one different?
PALCA: There are drugs known as monoclonal antibodies, and they do work to reduce the likelihood that someone with a coronavirus infection will get seriously ill or die. But Annie Luetkemeyer says there are challenges when it comes to using these monoclonal antibody therapies. Luetkemeyer is a professor of medicine at the University of California, San Francisco.
ANNIE LUETKEMEYER: There are issues with supply availability. You have to come to some kind of a medical center to get either an IV or a subcutaneous infusion. And the fact is that for most people, they just aren't receiving this both in resource-limited and in less resource-limited settings.
SIMON: So does this new drug appear to avoid some of those issues that can limit how people get it?
PALCA: Yeah, it's a pill. No need for needles. No need for a visit to the hospital or a special infusion center. You go to the pharmacy. But Luetkemeyer says there are challenges here, as well. The evidence is, for the drug to work well, you have to give it to someone early in the course of the disease. And now, Merck was originally testing the drug on people that were hospitalized with COVID, and it wasn't working that well. So they abandoned that and went to testing people within five days of exhibiting symptoms. So that means that earlier in the illness seems to be better. But Luetkemeyer says that means doctors are going to have to move fast if they suspect someone has COVID-19.
LUETKEMEYER: It really is going to put the onus on us making sure that we're able to test people quickly, so they have access to, you know, testing and then, if they're positive and symptomatic, that we get them treatment very quickly.
PALCA: And in fact, some people have suggested this drug might be used as a preventative if you've been exposed to COVID, but it's definitely not an alternative to vaccination. That's still the best way to prevent COVID illness.
SIMON: Joe, do we know if this new treatment has any - as many do - has any downsides that have to be accounted for, as well?
PALCA: Well, from the trials, not anything obvious. But there have been questions about this particular drug and whether it causes genetic alterations, so it may not be recommended for people who are pregnant. But that's not so unusual. There are many drugs that are not supposed to be used during pregnancy.
SIMON: NPR's science correspondent Joe Palca, thanks so much.
PALCA: You're welcome. Transcript provided by NPR, Copyright NPR.
