Merck announced the end of research for two candidate vaccines, including one that the pharmaceutical company was developing with the Institut Pasteur.
For these two vaccines, the story ends here. The results of the first clinical trials were considered disappointing, as the vaccines did not generate a sufficiently strong immune response. In fact, the induced responses were lower than those seen in people cured of a natural infection as well as those seen with approved vaccines (those from Pfizer-BioNTech and Moderna), suggesting low efficacy.
“Following interim results of a phase I clinical trial, the Institut Pasteur is halting the development of one of its vaccine candidates, the one based on the measles vaccine virus,” the French institute announced in a report. communicated. The latter is continuing the development of two other potential vaccines, one administered by the nasal route and a DNA vaccine, which are however only in the preclinical phase.
The vaccine in question, named V591, was based on the use of the virus used in the measles vaccine. This harmless virus “carries” instructions for building the S protein of the coronavirus into the cells of the vaccinated person.
Merck is also ceasing trials with its V590 vaccine, which were also disappointing after phase I. Developed in collaboration with the public-private partnership IAVI (International Initiative for a Vaccine Against AIDS), V590 was based on a vector other than the virus of measles, the vesicular stomatitis virus (VSV), used for the vaccine against Ebola fever.
In both cases, these vaccines used vectors capable of replicating in the host’s cells and therefore potentially allowing a prolonged effect. The researchers hoped that a single dose would be sufficient. This would have represented a significant advantage over other vaccines already approved. Note that no safety concerns were noted during the tests.
The American company Merck is, however, continuing its research into two potential treatments for COVID-19.