The vaccine, which is vaccinated in more than 50 countries, was useless against “omicron”

(ORDO NEWS) — Many people around the world have been vaccinated with the Chinese-made CoronaVac vaccine. According to scientists from the United States and the Dominican Republic, apparently, this drug provides little protection against the omicron strain with several dozen mutations in the S protein that has been spreading in recent months.

The CoronaVac vaccine, developed by the Chinese company Sinovac and approved in 52 countries, provides little to no protection against the micron strain. This follows from a study by scientists from the Yale University School of Medicine (USA) and employees of the Dominican Ministry of Health, which was published in the journal Nature Medicine . Millions of people around the world could be affected by a new variant of the virus.

To assess adaptive humoral immunity, the authors analyzed plasma samples from 101 adults from the Dominican Republic, who were first vaccinated with two doses of the Chinese vaccine in the summer of 2021, and then, at least four weeks later, were revaccinated with BNT162b2 from Pfizer and BioNTech.

Blood was collected before the third vaccination, as well as a week and 28 days after it, and exposed to SARS-CoV-2, testing the ability of antibodies to neutralize the original, “Wuhan” strain, “delta”, and finally “omicron”.

“The titers of virus-specific immunoglobulins of the IgG class rose on the seventh day compared to the initial level and increased even more on the 28th day after revaccination. People vaccinated with CoronaVac and subsequently given a booster shot of BNT162b2 developed high levels of IgG that were comparable to those of healthcare workers who received two doses of the mRNA vaccine, ”the researchers write.

Participants initially vaccinated with the Chinese preparation showed a 10.1- and 6.3-fold increase in the neutralizing activity of antibodies against the Wuhan strain and Delta, respectively, almost a month after the Pfizer revaccination. However, when it came to the “omicron”, things were not so happy.

“In our cohort of healthcare workers, we observed a 14.5-fold reduction in titers against the omicron variant 28 days after the second dose of the Moderna vaccine,” the scientists said. In the case of patients from the Dominican Republic who received booster vaccinations, “omicron” was 7.1 times less sensitive to neutralizing antibodies than the original strain of SARS-CoV-2, and 3.6 times less sensitive than “delta” (after 28 days after revaccination).

“In the blood plasma of those who received two doses of CoronaVac, there were no neutralizing antibodies to Omicron before the booster dose of BNT162b2,” the authors of the work emphasized.

In 80% of the study participants, antibodies to the new strain nevertheless formed, but only after revaccination with the BNT162b2 preparation: however, the titers became only 1.4 times higher, that is, they remained reduced compared to the Wuhan strain and the delta variant.

According to scientists, residents of countries where they were vaccinated mainly with the CoronaVac vaccine need to be revaccinated. Although Omicron has reduced the effectiveness of all Covid-19 prevention drugs, including booster doses , in most cases, vaccinations still protect against severe disease.

Sinovac used an inactivated version of the virus to produce the vaccine. The drug is administered in two doses with an interval of two to four weeks. According to last year’s study by Brazilian experts from the Institute of Butantan, the effectiveness of CoronaVac against mild Covid-19 was 78.4%, against severe – 100%.

Real data from Peru showed that two doses reduced the likelihood of contracting coronavirus by only 50.4%, and the risk of death by about 94% (although researchers from Yale University claimed 85% protection from hospitalization with Covid-19 and 80 % protection from death).

CoronaVac has been approved by such states as Armenia, Georgia, Ukraine, Moldova, Kazakhstan, Tajikistan, Turkey, Mexico, Egypt, Ecuador, Tanzania and many others. About 60 million doses have been delivered to Europe alone, according to Oxford University.


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