Britain on Thursday became the first country in the world to approve a potentially game-changing COVID-19 antiviral pill jointly developed by U.S.-based Merck (MRK.N) and Ridgeback Biotherapeutics, in a boost to the fight against the pandemic.

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, citing clinical data.

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

Treatments to tackle the pandemic, which has killed more than 5.2 million people worldwide, have so far focused mainly on vaccines. Other options, including Gilead’s (GILD.O), infused antiviral redeliver, and generic steroid dexamethasone, are generally only given after a patient has been hospitalized.

Merck’s Molnupiravir has been closely watched since data last month showed it could halve the chances of dying or being hospitalized for those most at risk of developing severe COVID-19 when given early in the illness.

The drug, to be branded Lagevrio in Britain, is designed to introduce errors into the genetic code of the virus that causes COVID-19 and is taken twice a day for five days.

The British government and the country’s National Health Service (NHS) will confirm how the treatment will be deployed to patients in “due course”.

“We are working at pace across the government and with the NHS to set out plans to deploy molnupiravir to patients through a national study as soon as possible,” health secretary Sajid Javid said in a statement.

The speedy approval in Britain comes as the government struggles to tame soaring infections.

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 five times more people.

Data released on Wednesday night showed COVID-19 prevalence in England hit its highest level on record last month, led by a high number of cases in children and a surge in the southwest of the country. read more

Pressure is growing on the government to implement its “Plan B” aimed at protecting the NHS from unsustainable demands, involving mask mandates, vaccine passes, and work-from-home orders.

Last month, Britain agreed on a deal with Merck to secure 480,000 courses of molnupiravir.

TREATMENT RACE

In a separate statement, Merck said it was expecting to produce 10 million courses of the treatment by the end of this year, with at least 20 million sets to be manufactured in 2022.

The U.S.-based drugmaker’s shares were up 2.1% at $90.54 before the market opened.

Pfizer (PFE.N) and Roche (ROG.S) are also racing to develop easy-to-administer antiviral pills for COVID-19. Pfizer last month began a large study of its oral antiviral drug for the prevention of COVID-19 in people exposed to the coronavirus.

Merck’s molnupiravir is also being studied in a late-stage trial for preventing infection.

Viral sequencing done so far has shown molnupiravir is effective against all variants of the coronavirus, Merck has said, including the more-infectious Delta, which is responsible for the worldwide surge in hospitalizations and deaths recently.

While it is not yet clear when Merck will deliver doses to Britain, the company has said it is committed to providing timely access to its drug globally with plans for tiered pricing aligned with a country’s ability to pay.

Merck is also in talks with generic drugmakers about expanding manufacturing licenses to build a supply of the treatment.

Antibody cocktails like those from Regeneron (REGN.O) and Eli Lilly (LLY.N) have also been approved for non-hospitalized COVID-19 patients, but have to be given intravenously.