China's Sinovac COVID-19 vaccine booster 'ineffective' against Omicron: Hong Kong study

A third booster shot of China’s widely used Sinovac’s CoronaVac vaccine has been found ineffective against the highly complex and mutated B.1.1.529 Omicron variant of concern, researchers said in a new study published on December 25. The China-made jab does not provide sufficient protection against Omicron, scientists at the University of Hong Kong (HKU) and the Chinese University of Hong Kong revealed, adding that the third shot of one of the world's most widely used COVID-19 vaccines mostly also donated by China to other countries does not produce enough levels of virus-neutralising antibodies to fight against Omicron.

Sinovac’s CoronaVac and state-owned Sinopharm’s BBIBP-CorV vaccine are the two most-used vaccines in China as well as widely exported to other nations by Beijing.    

'94% develop neutralising antibodies': A claim debunked 

The new study contradicts Chinese biotech company Sinovac’s claims that its third dose of COVID-19 vaccine offers 94% efficacy against the new COVID variant Omicron. The Chinese pharmaceutical company conducted research claiming that the third booster shot from their vaccine showed that it doubled the neutralising antibody positive rate against Omicron, the Chinese government-affiliated newspaper Global Times reported. Sinovac stated that it has conducted the study on 20 participants who were earlier administered with two shots of Sinovac COVID-19 vaccine and separately at least 48 were administered the booster shot. 

Of those that received the booster, 45 developed the neutralising antibodies against the Omicron, Sinovac’s study claimed. Sinovac said that 94% of those who received three shots of Sinovac including the third booster generated neutralising antibodies to fend off Omicron’s severe impact. But researchers have now found that the three doses of Sinovac’s COVID-19 vaccine did not produce adequate levels of antibodies. The company was reached for comments but hasn’t issued a response. The study claims that Pfizer-BioNTech's mRNA vaccine is more effective at providing 'protective levels' of antibodies when administered as the third booster shot among those who received two shots of Chinese manufactured CoronaVac. Meanwhile, Pfizer and its German partner BioNTech earlier declared that its three-shot regime [including the third booster] was able to neutralise the B.1.1.529 Omicron effectively.