In what could be a U.S. pandemic first, drugmaker Merck will apply for federal emergency use authorization for an antiviral pill to treat COVID-19, the company announced Friday.

Molnupiravir, developed in collaboration with Ridgeback Biotherapeutics, slashed the rate of hospitalization or death by 50% in people with COVID-19 when compared to placebo, Merck said. The drug was tested in at-risk, non-hospitalized adult patients with mild-to-moderate COVID-19. Trial recruitment has been stopped due to the positive results.

The drug’s efficacy was not affected by the timing of symptom onset or by study participants’ underlying risk factors. What’s more, among the 40% of participants with available viral sequencing data, the drug was effective against three major viral variants — gamma, delta and mu, the company said.

Oral drug convenience

The drug may be the first pill authorized to treat COVID-19 in the United States — if federal regulators sign off on the new trial data. 

Antivirals block the ability of a virus to replicate and spread further throughout the body. Treatment in pill form — taken to prevent or lessen the effects of the disease — could offer unprecedented convenience when compared to the limited treatment options currently available in the United States, Merck and Ridgeback Therapeutics said. 

“With the virus continuing to circulate widely, and because therapeutic options currently available are infused and/or require access to a healthcare facility, antiviral treatments that can be taken at home to keep people with COVID-19 out of the hospital are critically needed,” said Wendy Holman, CEO of Ridgeback Biotherapeutics.

U.S. set for quick distribution

The stage has been set for quick U.S. distribution of molnupiravir. The U.S. government earlier this year agreed to purchase 1.7 million courses of the drug if it is approved under emergency use authorization or is fully approved by the FDA.

Merck is by no means alone among drugmakers hoping to get a COVID-19 antiviral pill to market. Pfizer’s drug PF-07321332 now is in late stage trials to assess its effects in non-hospitalized, symptomatic adult participants. And at least one company is testing its drugs directly in nursing home residents.

Favipiravir, a drug already approved in Japan as a pandemic flu treatment, and in India and Russia as a COVID-19 treatment, is being given in long-term care facilities in the United States and Canada as part of a phase 2 trial approved by the FDA in August. This long-term care facility trial is expected to be completed in November.

Among already-approved treatments, the Food and Drug Administration has authorized the use of the antiviral remdesivir (Veklury) for the treatment of COVID-19 in May, but that drug is approved only for hospitalized patients and must be delivered intravenously. Monoclonal antibody treatment, offered to non-hospitalized, at-risk adults to prevent severe COVID-19 outcomes, must also be delivered intravenously or, as in the case of REGEN-COV, subcutaneously in a series of four injections.

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