The antiviral pill molnupiravir reduced the risk of COVID-19 hospitalization by 65% in a new study by Indian researchers that offered stronger results than previous research about the drug’s effectiveness.

The study, led by a researcher at the Chennai Antiviral Research and Treatment Clinical Research Site, split 1,218 Indian adults infected with the coronavirus and experiencing mild symptoms into comparably sized groups.

Only 1.5% of the group that received the pill required hospitalization, compared with 4.3% of the group that didn’t receive the pill.

A study last year by Merck, which developed the pill with the help of Ridgeback Biotherapeutics, found that the drug reduced the risk of hospitalization by 30%.

The previous study had several differences that make comparison difficult, Dr. Eliav Barr, senior vice president of Merck Research Laboratories, said in an interview Saturday.

Participants in the Merck study were at high risk of developing complications after a COVID-19 diagnosis, Barr said. The study also was conducted globally and included patients with both mild and moderate infections. The Indian study didn’t target patients at high risk.

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Still, “there are a lot of similarities in the studies,” he said. “Both studies show reductions in hospitalization. Both studies show reduction in viral load, that is, the amount of virus you can detect in the nose, from before to after treatment. And both studies had substantial improvement in symptom resolution.”

Antiviral pills such as molnupiravir and Pfizer’s Paxlovid have the potential to reach more people than the antibody treatments that are being widely used in the United States for high-risk COVID-19 patients. Since the start of the pandemic, scientists have hoped for convenient treatments that could be prescribed by any doctor and picked up at a local drugstore.

The Food and Drug Administration in December authorized molnupiravir for emergency use by certain adults who were at high risk. The drug is available by prescription only and should be started within five days of symptoms, the FDA said, adding that it’s not a substitute for vaccination.

Merck’s pill works by introducing errors into the virus’s genes to stop it from replicating, which has raised concerns about the risk that it could cause reproductive harm. The risk is hypothetical, and Merck says it has not been borne out in its studies.

The FDA said that women who were pregnant should generally not take the pills, but that there could be exceptions. The agency said women who may become pregnant should use contraception while taking the pills and for at least four days after. The male partners of women who could become pregnant should use contraception while taking the pills and for at least three months after, the agency said.

Some scientists have also raised concerns that the pills could in theory cause the virus to mutate in a way that does not stop it from replicating but instead leads to the emergence of a new variant.

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Demand for the Merck pill has been weak in the United States because of the low reported efficacy and the safety concerns.

Until the availability of antiviral drugs, patients who wanted treatment for COVID-19 needed to go to a facility to get an infusion or injection, Barr said.

“That’s a pretty substantive barrier to being able to get treatment,” he said. “And it’s a barrier that’s more likely to be disproportionately high in patients with the least access to health care.”