The pill, known as molnupiravir or Lagevrio, is licensed for those aged 18 and over (Picture: Reuters)

It is hoped that Ridgeback Biotherapeutics and Merck Sharp & Dohme’s (MSD) antiviral treatment, which can be taken at home, will dramatically improve outcomes for patients and ease the strain on the NHS.

The UK is the first country to give the treatment the green light, although it was not immediately clear how quickly the pill would be available, with supply expected to be limited.

The treatment, known as molnupiravir or Lagevrio, has been licensed for those aged 18 and over who test positive for the virus and have at least one risk factor for developing severe disease.

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, British officials announced they secured 480,000 courses, with thousands of vulnerable Brits expected to have access to the treatment this winter via a national study.

Health Secretary Sajid Javid said: ‘Today is a historic day for our country, as the UK is now the first country in the world to approve an anti-viral that can be taken at home for Covid-19.

Merck is making the pill, which can be taken at home, with Ridgeback Biotherapeutics (Picture: AP)

‘This will be a gamechanger for the most vulnerable and the immunosuppressed, who will soon be able to receive the ground-breaking treatment.

‘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.

‘This antiviral will be an excellent addition to our armoury against Covid-19, and it remains vital everyone comes forward for their life-saving Covid-19 vaccine – particularly those eligible for a booster – to ensure as many people as possible are protected over the coming months.’

Dr June Raine, the Medicines and Healthcare products Regulatory Agency (MHRA) chief executive, added: ‘Following a rigorous review of the data by our expert scientists and clinicians, we are satisfied that Lagevrio (molnupiravir) is safe and effective for those at risk of developing severe Covid-19 disease and have granted its approval.

‘Lagevrio is another therapeutic to add to our armoury against Covid-19.

‘It is also the world’s first approved anti-viral for this disease that can be taken by mouth rather than administered intravenously.

‘This is important, because it means it can be administered outside of a hospital setting, before Covid-19 has progressed to a severe stage.

‘With no compromises on quality, safety and effectiveness, the public can trust that the MHRA has conducted a robust and thorough assessment of the data.’

The drug is intended to be taken twice a day for five days by people at home with mild to moderate symptoms.

Doctors said the treatment would be particularly significant for people who do not respond well to vaccination.

Merck announced preliminary results last month showing its drug cut hospitaliaations and deaths by half among patients with early coronavirus symptoms – but the results have not yet been vetted by external scientists.

The company also did not disclose details on molnupiravir’s side effects, but said that rates of those problems were similar between people who got the drug and those who received dummy pills.

Initially studied as a potential flu therapy, 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 tumors.

Regulators are also considering approving the medication in the US, Europe and elsewhere.

Last week, Merck agreed to allow other drugmakers to make its pill, in a move aimed at helping millions of people in poorer countries get access.

Dr Mohga Kamal-Yanni, a senior health adviser to the People’s Vaccine Alliance, said: ‘Unlike the grotesquely unequal distribution of Covid-19 vaccines, the poorest countries will not have to wait at the back of the queue for molnupiravir’.

While other treatments have been cleared to treat Covid, including steroids and monoclonal antibodies, those are administered by injection or infusion and are mostly for hospitalized patients.