Merck Ends COVID Vaccine Program, Cites Inferior Immune Responses

Merck said in a statement it will record a pretax discontinuation charge in the fourth quarter for vaccine candidate V591, which it acquired with the purchase of Austrian vaccine maker Themis Bioscience, and V590, developed with nonprofit research organization IAVI.

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 was late to join the race to develop a vaccine to protect against the coronavirus, which has so far killed more than 2 million people and continues to surge in many parts of the world including the United States.

U.S. regulators in December authorized COVID-19 vaccines from Moderna Inc and partners Pfizer Inc and BioNTech SE, and tens of millions of doses of both have so far been administered globally. Rivals Johnson & Johnson, AstraZeneca Plc and others are also racing to develop safe and effective vaccines to protect against the virus.

Merck said it will 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. Merck said a phase 2/3 trial of the drug is set to finish in May, but initial efficacy results are due in the first quarter and will be made public if clinically meaningful.

Merck said results from a phase 3 study of MK-7110, an immune modulator being studied as a treatment for patients hospitalized with severe COVID-19, are expected in the first quarter. In December, the company announced a deal to supply MK-7110 to the U.S. government for up to about $356 million.

(Reporting By Deena Beasley Editing by Shri Navaratnam)