LONDON — Britain has granted conditional authorization to Merck's coronavirus antiviral pill, the first pill shown to successfully treat COVID-19.

The U.K. is the first country to OK the treatment, but it wasn't immediately clear how quickly the drug, known as molnupiravir, would be available.

It's intended to be taken at home twice a day for five days by people with mild to moderate COVID-19.

Last month, Merck said trials showed the drug cut down on hospitalizations and deaths in adult patients with laboratory-confirmed mild to moderate COVID-19 who had at least one risk factor associated with poor disease outcomes.

The pill, which has been proven to reduce symptoms and speed recovery, could prove to be groundbreaking. Officials believe it could ease caseloads on hospitals and help to curb outbreaks in poorer countries with fragile health systems.

Merck has already signed an agreement with the U.N.-backed Medicines Patent Pool to allow other drugmakers to produce the pill, which will help increase supply worldwide upon approval.

Molnupiravir is also pending review by regulators in the United States and the European Union.

After Merck released clinical trial results, White House medical adviser Dr. Anthony Fauci said the data on the drug was promising.

"There was a 50% diminution of importance, is that in the placebo group there were eight deaths and in the treatment group, there were no deaths. That's also very important and very good news," Fauci said.

The federal government has already purchased 1.7 million doses of Merck's drug with the option to purchase more.