Merck has terminated development of two COVID-19 vaccines

Merck has terminated development of two COVID-19 vaccines due to poor immunity.

According to CNN and other media reports, the US pharmaceutical company Merck announced on January 25 that the two new coronavirus vaccine candidates under development are not as effective as the immunity produced by natural infection or other new coronavirus vaccines, and will terminate research and development.

Merck said that volunteers were well tolerated after being vaccinated with candidate vaccines V590 and V591, but compared with other competitors’ COVID-19 vaccines, they produced a poor immune response. The company plans to provide the results of the first phase of the vaccine for publication in peer-reviewed journals.

Let us review the “birth” of these two vaccines. At the end of May last year, Merck announced the acquisition of Themis Bioscience and started the development of a n COVID-19 vaccine candidate V591 based on the measles vector. The vaccine V590 is based on the company’s Ebola vaccine technology and developed together with the International AIDS Vaccine Initiative.

In November last year, Roger Perlmutter, head of drug development at Merck, introduced in a forum that V591 was genetically engineered to express the spike protein of the new coronavirus to stimulate the body’s immunity. The vaccine entered Phase I clinical trials in the third quarter of 2020, with a total of 300 healthy volunteers participating. V590 entered phase I clinical trials a few weeks later than V591. It can also produce a sustained immune response against the spike protein of the new coronavirus and can be used single-time. Both vaccines can be stored and transported at 4 degrees Celsius. If approved, Merck said it will be able to prepare millions of doses of the above two vaccines in a short period of time, as well as the ability to prepare hundreds of millions of doses.

Unfortunately, the research on these two vaccines failed to achieve the desired results. Merck announced that after discontinuing these two vaccines, the company will make every effort to advance the clinical research of two candidate COVID-19 treatment drugs, MK-7110 and MK-4482, and expand the production scale.

MK-7110 therapy may suppress the overactive immune response caused by the new coronavirus pneumonia and minimize its destructive effects on human organs. Data from the Phase III clinical study showed that the risk of death or respiratory failure was reduced by more than 50% in hospitalized patients after using a single dose of MK-7110. MK-4482 is an oral medicine that can inhibit the replication of the virus in the carrier and help prevent the spread of the virus in the community.

Currently, there are still 64 candidate vaccines in clinical trials around the world. The COVID-19 vaccines of Pfizer and Moderna have been authorized for emergency use in the United States, and vaccinations have been initiated in Europe. Both companies claim that the vaccine can provide 95% protection after two vaccinations; AstraZeneca vaccines are already on the market in some countries, but It has not been authorized by the United States; Johnson & Johnson will announce the results of a large-scale vaccine single-dose trial at the end of this month; Novavax is in the phase III clinical trial phase and will announce the results of the study in the first quarter of this year.

(source:internet, reference only)

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