Britain has granted a conditional authorisation to Merck’s coronavirus antiviral pill, the first shown to successfully treat Covid-19 at home.
It is the first country to approve the treatment, although it was not immediately clear how quickly the pill, called molnupiravir, would be available.
The pill was licensed for adults aged 18 and older who have tested positive for Covid-19 and have at least one risk factor for developing severe disease.
“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-19,” said Health Secretary Sajid Javid.
“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.”
The UK's Medicines and Healthcare products Regulatory Agency said the drug is safe and effective at reducing the risk of hospital admission and death in people with mild to moderate Covid who are at extra risk from the virus.
Molnupiravir, is intended to be taken twice a day for five days by people at home.
An antiviral pill that reduces symptoms and speeds up recovery could prove groundbreaking, easing caseloads in hospitals and helping to curb outbreaks in poorer countries with fragile health systems.
It would also bolster the two-pronged approach to the pandemic: treatment, by way of medication, and prevention, primarily through vaccinations.
Merck has said it can produce 10 million treatment courses through the end of the year, but much of that supply has already been purchased by governments worldwide.
In October, UK officials said it had secured 480,000 courses of the drug and expected thousands of vulnerable Britons to have access by winter.
Doctors said the treatment would be particularly significant for people who do not respond well to vaccination.
The drug targets an enzyme the coronavirus uses to reproduce itself, inserting errors into its genetic code that slow its ability to spread and take over human cells. That genetic activity has led some independent experts to question whether the drug could potentially cause mutations leading to birth defects or tumours.
Molnupiravir, which was initially studied as a potential flu therapy with funding from the US government, is also pending review at regulators in the US and Europe.
Merck’s preliminary test results have not yet been reviewed by outside scientists.
The company also did not disclose details on side effects, except to say that rates of those problems were similar between people who got the drug and those who received dummy pills.