The UK has become the first country to approve an anti-viral pill to treat COVID.
The Medicines and Healthcare products Regulatory Agency (MHRA) recommended that the drug, molnupiravir, be used as soon as possible following a positive COVID-19 test and within five days of the onset of symptoms.
Molnupiravir is the first dedicated oral antiviral treatment for COVID.
The government and the NHS will confirm how it will be deployed to patients in due course.
Watch: UK shows interest in antiviral pill molnupiravir after trial shows it halves rate of hospital admission and death
Health and Social Care Secretary Sajid Javid said the "game-changing" treatment would be used for the most vulnerable and the immunosuppressed.
He added: “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.”
MHRA chief executive Dr June Raine said the approval of a drug that can be taken orally rather than intravenously was important as it meant the drug could be administered outside of a hospital setting before COVID-19 progresses to a serious stage.
Developed by Ridgeback Biotherapeutics and Merck Sharp & Dohme (MSD), molnupiravir works by interfering with the virus’ replication. This prevents it from multiplying, keeping virus levels low in the body and therefore reducing the severity of the disease.
It has been authorised for use in people who have mild to moderate COVID-19 and at least one risk factor for developing severe illness. Such risk factors include obesity, older age (>60 years), diabetes mellitus, or heart disease.
The government announced last month that it had secured 480,000 courses of molnupiravir after a study found it cut the rate of hospital admission and death by 50% in mild-to-moderately ill patients who had at least one risk factor for the disease.
In the study, the tablet was given twice a day to patients recently diagnosed with coronavirus.
Dr Raine said: "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."
In October, the UK secured deals for two COVID-19 antivirals, one developed by Merck and the other by Pfizer, which it said could be used to treat patients by the end of the year if regulatory approval is granted.
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