A pill to treat COVID-19 just got closer to reality, as the Food and Drug Administration's expert panel voted Tuesday in favor of green-lighting Merck's antiviral treatment.

The thumbs-up was not without controversy, however, as several panelists raised concerns over the drug's safety risks and modest efficacy levels. Overall, the group voted 13-10 that the benefits outweigh the risks of using the drug for infected people at high risk of severe disease who are within five days of developing symptoms.

But several voting members said they wanted to specifically exclude women who are pregnant from authorization.

"I think the FDA should not approve it for the use in pregnant women except under really exceptional circumstances," said David Eastman, a biology professor at University of California, Riverside, who voted yes.

"I think they should limit it to high-risk individuals."

Others said the decision should be left up to the pregnant person considering taking the drug, along with a medical counselor who may help inform the decision.

"As a woman of child-bearing age, I don't think I would want to take this drug, not knowing the effects it could have on my unborn child," said Roblena Walker, a consumer representative selected to advise the committee. She voted yes, given that the drug's risks and benefits will be weighed further before it is authorized.

The FDA is still reviewing the drug, called molnupiravir, and deciding whether to grant an emergency use authorization. While the agency typically follows the advice of its expert panel, it is not required to do so.

In a clinical trial, Merck enrolled more than 1,400 unvaccinated people who recently got COVID-19 and are at high risk of severe disease. Volunteers randomly received either Merck's treatment, a 40-pill regimen given over five days, or dummy pills that acted as a control group.

The final analysis showed Merck's drug reduced hospitalizations and deaths by 30 percent. That figure took experts and analysts by surprise, as an interim analysis announced in October showed a 48 percent reduction.

The FDA also highlighted several safety concerns with the drug in its review of lab and animal studies. The agency noted several potential risks, including risk to fetuses, impaired bone and cartilage growth, and mutagenicity.

These safety risks come from Merck's drug being a nucleoside, a type of antiviral that intentionally inserts errors into the copying process of a virus. This obstructs the virus' quest to replicate itself. But that also carries the theoretical risk the drug could interact and mutate human cells, with scientists debating how serious a risk this is.

Those safety risks were enough of a reason for some voting members to determine the risks outweighed the benefits.

"I felt that the overall absolute effect in the total trial population was modest at best," said Dr. Sankar Swaminathan, a an infectious-disease expert at the University of Utah Health, who voted no.

"The risk of mutagenic effects on the patient is not firmly established or characterized, and given the large potential population affected, the risk of widespread effects on potential birth defects and especially delayed effects on the male has not been adequately studied."

Merck's drug could be the first COVID-19 pill

If approved, molnupiravir would be the first pill to treat COVID-19, an advance that could simplify and expand access to medical care for patients. While several antibody therapies have been authorized, they are expensive and can require a lengthy IV infusion.

Molnupiravir was originally developed as a treatment for the flu. Merck licensed the drug in July 2020 from Ridgeback Biotherapeutics, a small Miami biotech.

The federal government is betting big on molnupiravir. In June, the US agreed to pay US$1.2 billion for enough pills to treat 1.7 million people. And in November, it reached a second deal to secure 1.4 million more treatment courses. In total, US$2.2 billion is on the line, with both deals contingent on the FDA authorizing the treatment.

But analysts are already expecting Merck's pill may not be widely used. Cowen analyst Steve Scala wrote in a Monday research note he thinks it will be mainly used when other treatment options aren't available.

That is because of competing drugs, notably Pfizer's COVID-19 pill, showing much higher efficacy and not carrying the safety concerns of molnupiravir.

Better drugs may be on the horizon

Some committee members hinted that there is room for improvement from Merck's drug.

"If there's an alternative therapy that's efficacious, like monoclonal antibodies currently or a future medicine, that would be the priority," said Dr. Uma Reddy, a professor of obstetrics, gynecology and reproductive sciences at Yale University.

In a similar patient population as Merck's study, Pfizer's pill reduced hospitalizations and deaths by 89 percent. That drug also doesn't carry the same mutagenic risks as Merck's, because it disrupts the virus in a different way, blocking an enzyme that plays a key role in the virus' copying process.

Wall Street analysts forecast Pfizer's pill to turn into a blockbuster drug. Morgan Stanley projects US$26 billion in 2022 sales, while SVB Leerink expects US$24 billion in 2022. The FDA is also reviewing Pfizer's drug for an emergency OK.

In the meantime, Merck's pill could be an option for populations with a high risk of developing severe COVID-19. John Coffin, a professor at Tufts University, voted yes with the suggestion that the initial authorization be reserved for high-risk groups, like individuals older than 60 who have not been vaccinated.

"I'm not sure if this is really the one we've been waiting for, but it's all we've got at the moment," Coffin said.

This article was originally published by Business Insider.

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