Merck's COVID-19 antiviral pill is the second authorized by the FDA

The medicine might not get as much use as its Pfizer rival.


Pfizer's COVID-19 antiviral pill will already have some competition in the US. As the Associated Press reports, the Food and Drug Administration has given emergency use authorization for Merck's Molnupiravir pill. The treatment limits replication of SARS-CoV-2 by inserting "errors" in the virus' genetic code while an infection is relatively young, ideally preventing mild or moderate cases from becoming severe in high-risk patients.

The medicine might not get as much use as Pfizer's Paxlovid, however. Merck's offering will only be available to those 18 years or older versus 12 years for Pfizer's, as there are concerns it might affect bone and cartilage development in younger patients. There are also warnings against using it during pregnancy or while attempting to conceive — the FDA said people should use birth control both during and after treatment, with women waiting days and men waiting three months.

Molnupiravir also doesn't appear to be as effective as Paxlovid. While Pfizer's solution reduced hospitalization and death by as much as 90 percent, Merck's only managed 30 percent. This pill may become the secondary option, particularly in situations where Paxlovid isn't available. Both companies' products are expected to remain effective against the virus' Omicron variant as they don't target mutating spike proteins.

Still, this might become another useful tool for minimizing COVID-19 hospitalizations and deaths. Pfizer's pill will be the most readily available when the US is ordering enough to treat 10 million patients, but there will be enough of Merck's drug to address 3.1 million. Even if the effectiveness is limited, that could spare hundreds of thousands of people from the worst the disease has to offer.