China’s Sinovac offers inadequate protection against Omicrons, study shows

Two doses of the Chinese-made Sinovac vaccine, one of the most commonly used vaccines in China and around the world, provides “insufficient” antibodies against the Omicron coronavirus variant, according to the researcher in Hong Kong.

The findings from a study published by the University of Hong Kong have raised concerns as Omicrons rise in many parts of the world and the first two cases were detected in mainland China this week.

China has administered more than 2.5 billion doses of Covid-19 vaccines – most of which are Sinovac or Sinopharm vaccines – and adopted a “no Covid” strategy that has put a lot of people under mandatory quarantine by the government. The new coronavirus has raised questions about effectiveness of Chinese vaccines and Beijing’s ability to control the virus.

“[Omicron] Nicholas Thomas, an associate professor at the City University of Hong Kong who specializes in Chinese foreign policy and health security in Asia, has made China’s vaccine even less effective in the face of concerns. threat posed by Covid. “The challenge for the Chinese authorities will be [to] re-engage the public’s commitment to another round of vaccines. ”

The Hong Kong study examined the antibody levels of 25 people who received both doses of Sinovac vaccine – an inactivated vaccine unlike messenger RNA injections like those developed by BioNTech/Pfizer – and found that no one had enough antibodies in their serum to neutralize the new variant.

In contrast, 5 out of 25 people who received two doses of the BioNTech/Pfizer vaccine were found to have detectable neutralizing antibodies against Omicron, which the researchers say are 20 to 20 “effective” 24% against the new variant.

Last week Pfizer said that its three stabs can disable Omicron based on a lab test.

Numerous laboratory studies have shown that the antibody protection provided by any two doses of vaccine is falsified by Omicron. Separate preliminary studies from the University of Oxford and the Medical College of Innsbruck found that many recipients of the dual Oxford/AstraZeneca vaccine did not produce any measurable neutralizing antibodies against Omicron.

The University of Hong Kong researchers said their study “has demonstrated that both Omicron variants have reduced susceptibility to neutralization by sera collected from Covid-19 vaccine recipients.” Not available [Sinovac] detectable neutral receiver [antibodies] for the Omicron variants. “

The level of antibodies sufficient to neutralize the virus is strongly related to its ability to prevent symptomatic infections, the researchers added. However, experts stress that people who get the dual vaccines will retain some protection against severe illness because this is mediated by T and B cells, not antibodies.

Kevin To, one of the HKU researchers, told the Financial Times that data on the third dose of Sinovac “will be needed” to determine whether people who have received two doses of Sinovac should switch to a different vaccine. repeat or not.

David Hui, a Hong Kong government pandemic adviser from the Chinese University of Hong Kong, said another study was underway on a 3-dose course of Sinovac vaccine to protect against Omicron. Results are expected to be announced next week.

A large number of populations in countries including Turkey, the Philippines, and Indonesia have received the Sinovac vaccine. Sinovac, said Wednesday its own laboratory test results showed a third dose could effectively improve Omicron’s ability to neutralize, but there was no immediate comment on the study.

Nine cases of Omicron have been recorded in Hong Kong as of Wednesday, just as final preparations to resume quarantine-free travel to mainland China are being made. Top adviser to the city’s leader Carrie Lam dismissed the concerns raised by the study.

“Currently, Hong Kong is using a Covid zero strategy to prevent infection. . . So don’t worry at all,” Lam Ching-choi, a medical doctor and a member of Lam’s de facto cabinet, told the FT. “[Omicron] did not [affected border reopening plans] in this time. . . Omicron cases are well preserved, [with] Are not [cases] spread into the community. ”

Additional reporting by Oliver Barnes in London

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