In a major setback, Merck to stop developing its two Covid-19 vaccines and focus on therapies

In a major setback, Merck to stop developing its Covid-19 vaccines - STAT Merck announced it is stopping development of both of the current formulations of the Covid-19 vaccines the company was working on. Matthew Herper STAT

Merck said Monday it will stop developing both of the current formulations of the Covid-19 vaccines the company was working on, citing inadequate immune responses to the shots.

Work will continue on at least one of the vaccines, which is being developed in partnership with the International AIDS Vaccine Initiative (IAVI), to see if using a different route of administration would improve how effective it is.

The announcement marks a shocking setback for one of the most storied vaccine makers, and will raise tensions around readouts expected soon from other companies, including Johnson & Johnson and the upstart NovaVax. ...

The results from a Phase 1 trial, described briefly in Merck’s press release, were resoundingly disappointing. The hope was that Merck’s vaccines, which were unique because they used viruses that could replicate once they were in the body, would be long-lasting, one-dose vaccines. The virus used for the vaccine being developed with IAVI is the one used in Merck’s successful vaccine against Ebola. The other vaccine used measles virus, a type of vaccine Merck has manufactured for decades.

Both vaccines, however, produced lower levels of antibodies against SARS-CoV, including binding antibodies and neutralizing antibodies, than is seen in the blood of individuals who have recovered from Covid-19. ...