On Jan. 28, 2022, Merck and Ridgeback Biotherapeutics announced data from six preclinical studies demonstrating that molnupiravir, an investigational oral antiviral COVID-19 medicine, was active against the SARS-CoV-2 variant Omicron (B1.1.529) in vitro.

The in vitro studies were independently conducted by researchers from institutions in six countries including Belgium, Czech Republic, Germany, Poland, the Netherlands and the United States. The studies used established cell-based assays to evaluate the antiviral activity of molnupiravir and other COVID-19 antiviral agents against SARS-CoV-2 variants of concern, including Omicron.