New Delhi, Dec 23 (IANS): A day after authorising the first anti-viral pill to treat Covid 19, the US Food and Drug Administration on Thursday authorised a second, Mercks Molnupiravir, USA Today reported.

The prescription medication, which can be taken at home, is designed to stop the progression of COVID-19 from mild to severe symptoms in people at high risk, the report said.

In data presented to an FDA advisory panel in late November, the drug was shown to prevent 30 per cent of infections from progressing - far fewer than Pfizer's antiviral Paxlovid, which the FDA authorized on Wednesday, the report added.

Molnupiravir should be given within five days of Covid-19 symptoms beginning and should only be given to adults because it may affect bone and cartilage growth, the FDA noted. The drug is not recommended for use during pregnancy because animal studies suggest it may damage the foetus.

Several doctors told USA Today that they would only prescribe molnupiravir if they had no other alternative, and the FDA seemed to echo that by noting in its authorisation announcement that the drug is to be used by people at high risk for severe disease "for whom alternative Covid-19 treatment options authorised by the FDA are not accessible or clinically appropriate".