COVID-19 | How effective are the Sinopharm and Sinovac vaccines against Omicron?

Studies on the efficacy of the vaccines of the Chinese pharmaceutical companies Sinovac, Sinopharm and CanSino against the omicron variant of the coronavirus are preliminary and, although they point to a decrease in its protective capacity, it is still too early to reach a conclusion on its usefulness.

Messages on Twitter and Facebook have been circulating in Latin America for days that assure that Chinese vaccines do not work against Ómicron.

For example, one user declares “antiCanSino” for being a vaccine while another account states that “Two doses and a booster of the COVID-19 vaccine made by Sinovac of China do not protect against omicron, according to a study”.

Other messages are in the opposite direction, such as that of a user who exposes in a tweet with more than 700 “I like you” that “Sinovac protects more than 90% omicron. This vaccine was criticized a lot and it turns out that it is now one of the most effective. “

Studies without peer review

Although preliminary studies report a decrease in the protection of vaccines from Sinovac and Sinopharm pharmaceutical companies, they have not been peer-reviewed (experts confirming the validity of the reported science) and only

These vaccines continue to protect against serious cases and death. While the CanSino preparation has not yet disclosed analysis.

The World Health Organization (WHO) requested on December 20 since the initial data that point to a decrease in immune protection come from laboratory studies, and “not from real life”.

WHO chief scientist Soumya Swaminathan said laboratory studies do not take into account other aspects of the immune system of individuals that play an extremely important role when it comes to protecting them from serious infection.

Mauricio Rodríguez, a professor at the Faculty of Medicine of the National Autonomous University of Mexico (UNAM), told EFE that to obtain a complete overview, “We must also study the immune cells T lymphocytes, which can recognize and destroy infected cells and are key to containing viral infections”.

If the studies focus only on measuring the level of antibodies, “The variability is going to be very large”the professor warned.

So far, the few studies that have been done on Chinese vaccines

Pending scientific review

The most cited study in the media on Sinovac in recent weeks was published by the University of Hong Kong. Its researchers determined that neither the CoronaVac vaccine from Sinovac nor the one from Pfizer-BioNTech is effective against the new variant.

Even so, the research – led by the prestigious infectious disease expert Yuen Kwok-yung – is pending peer review before publication and was based on the analysis of blood samples from 50 people, 25 of them immunized with the complete CoronaVac scheme and the other 25 with Pfizer.

Rodríguez stated that

In the same way, “We must take with caution” the results of another study done by the Ministry of Health of the Dominican Republic in collaboration with Yale University that found that two doses of Sinovac did not generate antibodies against omicron.

The most valuable thing, stressed the professor from UNAM, would be “Have information on the cases that are occurring in real life and look at their vaccination history.”

Rodríguez also noted: “Because if the efficacy is to prevent severe disease and death, it is very different from whether it is to prevent mild symptomatic disease. So far all vaccines are safe and effective in preventing serious illness and death. “.

Third dose, key to more immunity

Another study from Shanghai Jiao Tong University analyzed the immune response to the omicron variant with a third dose of Sinopharm.

The researchers found that this booster dose “significantly” increased the immune response to SARS-CoV-2 28 days after the injection, about 6.1 times greater than after the second. Regarding the Omicron variant, they described that it did reduce immunity by 20.1 times compared to another older Wuhan variant.

But the same scientists warned that “Real-world studies are still needed on the effectiveness of the protection of

Sinopharm is investigating the development of new vaccines against the latest covid variants, including Omicron, the drugmaker said, according to the state news portal China Internet Information Center.

CanSino has yet to study his response to Ómicron. The pharmaceutical company assured the Global Times newspaper that with a booster dose, the vaccine against this variant also stated that it was developing a new vaccine.

Both Sinovac and Sinopharm use inactivated viruses to trigger the production of antibodies that fight the coronavirus, while Convidencia – CanSino’s preparation – uses a virus other than SARS-CoV-2, less harmful, usually disguised with coronavirus proteins, to generate an immune response.

The three vaccines have a large presence in Latin America, with more than 280 million doses delivered.

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