Merck's new COVID drug molnupiravir gets FDA consideration : Shots - Health News The FDA is considering new pills that could treat people in early stages of COVID. Here's what to know about how they work, how effective they are and the impact they could make on the pandemic.

New antiviral drugs are coming for COVID. Here's what you need to know

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ARI SHAPIRO, HOST:

A new COVID-19 treatment was the topic of heated discussion today. At a public meeting, the drug company Merck made the case for its new antiviral pill. Advisers to the Food and Drug Administration grilled Merck representatives, and the panel eventually voted narrowly in favor of the drug, a critical step in getting it authorized for use. NPR's Pien Huang is here to explain.

Hi, Pien.

PIEN HUANG, BYLINE: Hi, Ari.

SHAPIRO: What is the pill and explain the debate over it.

HUANG: So the drug is called molnupiravir. It's made by Merck, and it's an antiviral pill. It messes with the virus' ability to copy itself. And the main problem is that it just doesn't really work that well. Early results had showed that the drug might be up to 50% effective at reducing hospitalizations and deaths from COVID, which would have been decent. It's about how well Tamiflu works against flu. But late last week, Merck announced that their full data results showed that the drug is just 30% effective, and doctors and scientists find those results disappointing.

SHAPIRO: How does that 30% figure compare to other COVID-19 treatments on the market?

HUANG: It's worse, but our toolkit is very limited. So this pill would be for people with mild to moderate COVID who are at risk of getting worse. And the only other available treatments right now for non-hospitalized COVID patients are monoclonal antibodies. These are pretty effective. They reduce the risk of getting hospitalized by about 70- to 85%.

But monoclonal antibodies are expensive to make and administer. People have to go to a clinic to get them as an IV infusion or a series of shots. Carl Dieffenbach, an official at the National Institutes of Health who's heading up the development of antivirals, says having pills to take at home could be a game changer.

CARL DIEFFENBACH: We need drugs. We need really effective antivirals, and we need more of them. And it'd be great if molnupiravir had held up because it would be in some ways an ace in the hole here, but it's not.

HUANG: Now, even if the drug is not the most effective, it does appear to reduce the risks of hospitalization somewhat. And now, when cases are rising and omicron is spreading, the country needs the tools that it can get. That's why 13 members of the FDA's advisory panel voted to recommend its use while 10 voted no. But they also recommended some limits to it based on concerns raised in today's meeting.

SHAPIRO: And what were those concerns?

HUANG: Well, there were two general concerns. One was that it might cause birth defects during pregnancy, and the FDA could address that by restricting use of the drug in people who are pregnant. Two was that it might, in very rare cases, spur the development of new virus variants.

Now, these concerns are largely theoretical, but they are based on how the drug works. The pill interferes with the virus' ability to make viable copies of itself by forcing it to make random errors when it tries, and those errors lead to dead viruses that can't spread or infect new cells. But there is a small risk that those errors could lead to a new virus variant that does spread. Here's James Hildreth, a panel member and president of Meharry Medical College, addressing Merck.

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JAMES HILDRETH: You're purposely mutagenizing the virus, which means that the likelihood of escape may be (ph) considerably stronger than it would be with those other kinds of treatments.

HUANG: The panel talked about ways to manage that risk; how it's important for people to take the full five-day course as prescribed, for people to quarantine and mask to make sure that any virus variants they develop don't spread. And Merck said that the scenario is very unlikely, but they couldn't quantify the risk.

SHAPIRO: So what are the next steps for this treatment?

HUANG: So if the FDA goes ahead and authorizes the pill, it would be the first take-it-home antiviral that's available. And it's far from perfect, but it could save some lives here and also in places where vaccines and antibodies are not very available.

And experts tell me other drugs are not far behind. The FDA is vetting an antiviral pill from Pfizer as well. It's called Paxlovid, and if it lives up to Pfizer's early analysis, it could reduce the risks of hospitalizations and death by almost 90%. A pill that effective could make a big difference in how COVID is treated.

SHAPIRO: That's NPR's Pien Huang.

Thank you.

HUANG: Thanks for having me.

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