Drugmaker Merck & Co said it would stop development of its two Covid-19 vaccines and focus pandemic research on treatments, with initial data on an experimental oral antiviral expected by the end of March, Reuters reports.

In early trials, both vaccines generated immune responses that were inferior to those seen in people who had recovered from Covid-19 as well as those reported for other Covid-19 vaccines, the company said.

Merck said it would focus Covid-19 research and manufacturing efforts on two investigational medicines: MK-7110 and MK-4482, which it now calls molnupiravir.

Molnupiravir, which is being developed in collaboration with Ridgeback Bio, is an oral antiviral being studied in both hospital and outpatient settings.