Third dose of China's Sinovac ineffective against Omicron, says study contrary to company's claim

China's Sinovac COVID-19 vaccine (CoronaVac) doesn't provide sufficient antibodies to fend off Omicron, a study by two Hong Kong universities has found.

The study examined the efficacy of a third dose of the CoronaVac and Pfzier-BioNTech vaccines against the new Omicron variant. This study was jointly conducted by the University of Hong Kong and the Chinese University of Hong Kong, Taiwan News reported.

The study showed that a third dose is given to participants who had received two previous doses of CoronaVac, "does not provide adequate levels of protective antibody," while the third dose of Pfzier-BioNTech did.

Out of the 25 people who received two doses of Pfzier-BioNTeh, only five developed a neutralizing ability against the two Omicron variants. Meanwhile, 25 people inoculated with two doses of CoronaVac, none produced a detectable antibody against Omicron.

This study runs contrary to the claim that Sinovac made earlier that found that a third dose was "effective in improving the serum neutralizing against the omicron strain."

The study done by the company said that 94 per cent of those who had received three Sinovac doses generated enough neutralizing antibodies. The company did not elaborate on what kind of antibody levels three shots produced.

The study was conducted by the company on 20 people who received two shots and another 48 who received three shots. Seven in the first group and 45 in the second tested positive in neutralizing antibodies against the Omicron variant, the company said in a statement, as quoted by the Global Times.

The Omicron variant, first discovered in early November, has been reported in 77 countries and regions, according to the World Health Organization.

( With inputs from ANI )