Britain on Thursday became the first country in the world to approve a potentially game-changing antiviral pill to treat COVID-19, jointly developed by U.S. pharma companies Merck and Ridgeback Biotherapeutics.

Britain's Medicines and Healthcare products Regulatory Agency (MHRA) recommended the drug, molnupiravir, be used as soon as possible following a positive COVID-19 test and within five days of the onset of symptoms.

The tablet will be given twice a day for five days to vulnerable patients recently diagnosed with the disease.

In clinical trials the pill, originally developed to treat flu, cut the risk of hospitalisation or death by about half.

It is the first antiviral medication for Covid which can be taken as a pill rather than injected or given intravenously.

The UK has agreed to purchase 480,000 courses with the first deliveries expected in November, according to a BBC report.

It cited UK Health Secretary Sajid Javid as saying the treatment was a "gamechanger" for the most frail and immunosuppressed.

In a statement he said: "Today is a historic day for our country, as the UK is now the first country in the world to approve an antiviral that can be taken at home for Covid."

This is the first oral antiviral treatment for COVID-19 to get approved, with the approval coming ahead of potential U.S. regulatory clearance. U.S. advisers will meet this month to vote on whether molnupiravir should be authorized.

The drug, to be branded Lagevrio in Britain, is designed to introduce errors into the genetic code of the virus that causes COVID-19.

The speedy approval in Britain comes as the country has about 40,000 daily cases of COVID-19, according to the latest seven-day average. That total is second only to the roughly 74,000 a day in the United States, which has a five times larger population.

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