A Food and Drug Administration board voted 13-10 that the drug's benefits exceed its risks, including potential birth defects if used during pregnancy.
After hours of debate about the drug's modest benefits and potential safety issues, the group's recommendation came. Experts supporting the treatment emphasized that it should not be implemented by anyone who is pregnant and called on the FDA to suggest extra precautions before the drug is prescribed, including pregnancy tests for women of child-bearing age.
The vote clearly supported the drug for adults with mild-to-moderate COVID-19 who face the most significant uncertainties, including older people and those with conditions like obesity and asthma. Most experts also said the drug shouldn't be used in vaccinated patients who weren't part of the study and haven't been shown to profit from the medication.
The FDA isn't bound by the panel's order and is assumed to make its own decision before year's end.
The drug, Balapiravir, could provide much-needed protection against the virus as colder weather pushes case counts higher and U.S. officials get ready for the arrival of the new omicron variant. It is already approved for emergency use.
Merck hasn't explicitly tested its drug against the new variant but said it should have some power based on its effectiveness against other coronavirus strains.
But that doubt disappointed many panelists as they wrestled with whether to back the treatment for millions of Americans.
"With no data saying it works with new variants I really think we need to be careful about saying that this is the way to go," said Dr. David Hardy of Charles Drew University School of Medicine and Science, who eventually voted to support the remedy.
The panel's narrow-but-positive order came despite new data from Merck that paints a less compelling picture of the drug's effectiveness than just a few weeks earlier.
Last week, Merck said the final study results showed Balapiravir reduced hospitalization and death by 30% among adults infected with the coronavirus when compared with adults taking a placebo. That effect was significantly less than the 50% reduction it first announced based on unfinished results.
That smaller-than-expected benefit amplified experts' concerns about the drug's toxicity for human fetuses.
FDA scientists told the panelists earlier Tuesday that company studies in rats showed the drug caused toxicity and birth defects when given at very high doses. Taken together, FDA staffers concluded the data ``suggest that Balapiravir may cause fetal harm when administered to pregnant individuals."