Merck Halts Development of its COVID-19 Vaccine Candidates

Merck, known as MSD outside the United States and Canada, announced on Jan. 25, 2021 that it is discontinuing the development of its SARS-CoV-2/COVID-19 vaccine candidates, V590 and V591, to focus on advancing its two SARS-CoV-2/COVID-19 therapeutic candidates, MK-4482 (molnupiravir) and MK-7110. MK-4482 (molnupiravir) is being developed in collaboration with Ridgeback Bio, a US-based biotechnology company.

According to a company press release, the decision came about after it was concluded that while the vaccines were well tolerated in Phase I clinical studies, the immune responses from participants were lesser to those seen following natural infection and those reported for other COVID-19 vaccines. Currently, the company is advancing clinical programs and scaling up manufacturing for its therapeutic candidates.

“We are grateful to our collaborators who worked with us on these vaccine candidates and to the volunteers in the trials,” said Dr. Dean Y. Li, president, Merck Research Laboratories, in the press release. “We are resolute in our commitment to contribute to the global effort to relieve the burden of this pandemic on patients, health care systems, and communities.”