NEW YORK: The US on Thursday authorized Merck & Co’s antiviral pill for COVID-19 for certain high-risk adult patients, a day after giving the go-ahead to a similar but more effective treatment from Pfizer Inc. Merck’s drug, molnupiravir developed with Ridgeback Biotherapeutics, was shown to reduce hospitalizations and deaths by around 30% in a clinical trial of high-risk individuals early in the course of the illness.

The U.S. Food and Drug Administration authorized Merck’s drug to treat mild-to-moderate COVID-19 in adults who are at risk for severe disease, and for whom alternative COVID-19 treatments are not accessible or clinically appropriate.

Pfizer’s drug, Paxlovid was authorized on Wednesday for people aged 12 and older and has shown to be nearly 90% effective in preventing hospitalizations and deaths in patients at high risk of severe illness, according to trial data.

The Pfizer treatment’s two-drug regimen may not be appropriate for some patients because it includes an older antiviral called ritonavir that is known to have interactions with some other prescription medicines.