In a boost to the fight against the pandemic, Britain became the first nation in the world to authorize a potentially game-changing COVID-19 antiviral drug produced jointly by Merck & Co and Ridgeback Biotherapeutics.

The Medicines and Healthcare Products Regulatory Agency in the United Kingdom has approved Molnupiravir for those who have mild to moderate symptoms of the virus and at least one risk factor for serious illness obesity, diabetes and heart disease.

The MHRA said it will be given as soon as feasible after a positive COVID-19 test and within five days of the commencement of symptoms.

The approval is the first for an orally administered COVID-19 antiviral medication and the first for such treatment that will be extensively used in the community.

On November 30, U.S. health experts will convene to assess the pill's safety and effectiveness and decide on whether it should be approved.

The medication in the form of a pill, known in Britain as Lagevrio, is designed to produce faults in the genetic code of the coronavirus that causes COVID-19. Doctors recommend taking the pill twice a day for five days.

In animal research, drugs in the same class as Molnupiravir have been related to birth abnormalities. Animal testing has shown that molnupiravir is safe, Merck said, which is known as MSD outside of the U.S. and Canada. However, the data has not yet been shared publicly.

Vaccines have been the mainstay of treatment for the pandemic, which has killed more than 5.2 million people around the globe. Other choices, such as Gilead's injected antiviral remdesivir and generic steroid dexamethasone, are usually administered only after a patient has been admitted to the hospital.

When taken early in the illness, Merck's Molnupiravir has been closely monitored since research in October revealed it could reduce the likelihood of death or being hospitalized for people most at risk of developing severe COVID-19.

Professor Stephen Powis, national medical director of the National Health Service in England, said the medicine will be given to patients who were at a higher risk of complications as British health officials prepare for one of the worst winters on record.