In a narrow Tuesday afternoon vote of 13-10, an advisory panel to the Food and Drug Administration (FDA) approved Merck’s COVID-19 pill. Molnupiravir is an oral antiviral drug initially hailed as a potential game changer in the battle against Covid since it can be taken at home instead of at a hospital like other treatments.

One source of hesitation that came up during the hours of FDA panel debate Tuesday is the lack of data showing significant benefits from the Merck COVID-19 pill. Last week, Merck revised the results of a previous study to reflect the pill is less effective than previously thought. The original Merck study, which was released early last month, found Molnupiravir reduced hospitalizations and deaths by half in people recently infected with the coronavirus. The revised results, which include over 1,400 patients instead of just 775, bumps the effectiveness down to 30%.

In addition, Merck hasn’t tested its pill against the new Omicron variant.

“As you can imagine, we are feverishly working to collect samples and do that,” Merck’s Senior Vice President of Clinical Research Dr. Nicholas Kartsonis said Tuesday. “We are committed to get those results out as soon as they are available.” He went on to tell the FDA panel he believes the Merck pill should have some potency based on its effectiveness against other strains of coronavirus.

“We now have results for Lambda and Mu, which are both variants of concern, and we see consistent efficacy from molnupiravir,” Kartsonis said. “When you look at the changes that are seen in Omicron, the changes that are seen are changes that are have been seen with other other variants that have already been shown to be effective.”

Another concern panelists had was regarding pregnancy. FDA scientists told the panel earlier that Merck studies in rats showed its pill caused toxicity and birth defects when given at very high doses. FDA staffers concluded the data “suggest that molnupiravir may cause fetal harm when administered to pregnant individuals.”

The FDA is weighing a blanket restriction against any use in pregnant women or allowing it in rare cases. However, some of the panelists say that decision should be left up to the mother and her doctor.

“I don’t think you can ethically tell a woman with COVID-19 that she can’t have the drug if she’s decided that’s what she needs,” panelist Dr. Janet Cragan said. “I think the final decision has to come down to the individual woman and her provider.”