Merck says it'll ask regulators to authorize the first antiviral pill designed to treat COVID-19 after a trial found it halved the risk of hospitalization or death

• Merck and Ridgeback say they'll apply "as soon as possible" to get their COVID-19 pill authorized.
• The companies said the drug, molnupiravir, halved the risk of hospitalization or death in a trial.
• If given the OK, the drug would be the first authorized antiviral pill designed to treat COVID-19.

A COVID-19 pill developed by Merck and Ridgeback Biotherapeutics halved the likelihood of death or hospitalization from the coronavirus in a study, interim results indicate.

The companies said Friday morning that they would apply for emergency authorization from the Food and Drug Administration "as soon as possible," adding that they had stopped recruitment into their study early because the results were so positive. They said they'd also seek authorization from regulators around the world.

If they get authorization, their drug, molnupiravir, would be the first antiviral pill on the market designed specifically to treat COVID-19 patients.

The phase-three trial involved 775 at-risk, nonhospitalized adult patients with "mild to moderate" COVID-19. An interim analysis found the drug "significantly reduced the risk of hospitalization or death," the companies said.

They said 7.3% of patients who received molnupiravir were hospitalized or died within 29 days, compared with 14.1% of placebo-treated patients.

Nobody who received molnupiravir died, compared with eight deaths among patients who received a placebo, the companies said.

All participants in the trial had at least one risk factor - such as obesity, heart disease, and old age - that made it more likely they'd develop a severe case of COVID-19, the companies said.

Merck and Ridgeback said molnupiravir reduced the risk of hospitalization and death across all underlying risk factors and had "consistent efficacy" across the Delta, Gamma, and Mu variants of the coronavirus. Delta has become the dominant strain in the US.

The federal government agreed in a $1.2 billion deal in June to buy enough molnupiravir pills to treat 1.7 million people if the drug received emergency-use authorization from the FDA.

Merck's stock was up 7.1% in premarket trading at 7:40 a.m. ET.