3 shots of Sinovac vaccine failed to protect against Omicron: New Study

A laboratory study indicated that two doses plus a booster of China’s Sinovac Biotech Ltd.’s Covid-19 vaccine, which is one of the most extensively used in the world, did not develop enough neutralizing antibodies to protect against the omicron form.

According to a study from the University of Hong Kong and The Chinese University of Hong Kong, for people who have been fully inoculated with the CoronaVac vaccine, obtaining a booster shot from Germany’s BioNTech SE considerably boosted protective levels of antibodies against omicron.

Two doses of the BioNTech vaccine, known as Comirnaty, were likewise insufficient, but adding a booster with the more potent mRNA vaccine increased protection to acceptable levels, according to the researchers. The findings are consistent with the vaccine producers’ conclusions.

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Sinovac produced lab findings this week claiming that 94 percent of those who received three doses developed neutralizing antibodies, though it didn’t specify at what level. Based on previous studies published in the journal Nature Medicine, the Hong Kong researchers established a threshold for what they considered an adequate quantity of antibodies for protection.

Officials from Sinovac did not immediately return calls requesting comment. While much remains unclear about how Sinovac’s shot reacts to omicron, particularly how T cells, the immune system’s weapon against virus-infected cells, would react, the preliminary findings constitute a setback for CoronaVac recipients. More than 2.3 billion doses of the vaccine have been made and distributed, largely in China and the poor countries.

The thought of having to send out a separate booster dose or perhaps re-vaccinate with a more omicron-specific vaccine, with omicron being around 70 times more transmissible than the delta form, will put back the world’s efforts to end the epidemic.

Malik Peiris and David Hui led the study, which looked at the generation of virus-neutralizing antibodies in the blood of patients who had received one of the two vaccines now in use in Hong Kong. They confirm that two doses of either vaccine aren’t enough to protect against omicron.