An advisory panel to the U.S Food and Drug Administration narrowly recommended authorization for Merck’s COVID-19 pill, days after new data showed the pill was less effective than originally thought. 

Molnupiravir works by inserting tiny errors into the coronavirus’ genetic code to stop it from reproducing. By a vote of 13-10, the panel said the drug’s benefits outweigh its risks—but only for adults who test positive and are at high risk of severe illness. 

The panel’s recommendation does not bind the FDA, which will likely make a final decision later this month. Officials in the United Kingdom have already authorized the pill.

What are the drug’s limitations? Most advisers said only unvaccinated people should use the drug and that women who may be pregnant should not take it. 

Last week, Merck said final study results showed molnupiravir cut hospitalizations and deaths from COVID-19 by 30 percent. But Merck has not specifically tested it against the new omicron variant, and that uncertainty gave some experts pause. 

Rival drugmaker Pfizer also has a COVID-19 pill under review.

This story originally appeared in WORLD. © 2021, reprinted with permission. All rights reserved.