On Thursday, researchers from the University of Hong Kong and the Chinese University of Hong Kong called on people to come forward and get a booster shot of Pfizer’s Comirnaty to protect themselves against the Omicron strain of Covid-19.
Their study, published on Thursday reveals that the CoronaVac shot, made by China’s Sinovac Biotech, failed to protect people against the Omicron variant even after three doses. “A third dose of CoronaVac given to those who received two previous doses of CoronaVac does not provide adequate levels of protective antibody,” the researchers stated.
“Those who had received two doses of either Comirnaty or CoronaVac should get a third dose of Comirnaty vaccine around six months after their second dose of vaccine to achieve optimal protection against Omicron variant,” Professor Malik Peiris, a co-author of the study, said in a statement.
The lab-based study investigated neutralizing activity in the blood of people inoculated with the Comirnaty or CoronaVac vaccines, both of which are currently in use in Hong Kong.
The researchers also noted that two doses of Pfizer’s Comirnaty shot did not provide adequate levels of protection, although the booster dose provided a sufficient neutralizing capability.
Last week, Sinovac cited lab studies saying 94% of people getting three doses of CoronaVac generated neutralizing antibodies. The quantity of said antibodies was not mentioned.
Despite concerns about the efficacy of CoronaVac, some 2.3 billion doses of the shot have been produced and shipped out globally, most of which have been rolled out in China and the developing world.
Many Western nations have embarked on ambitious booster campaigns in light of research suggesting the Omicron variant can evade vaccine-induced immunity after two doses of either the Pfizer, Moderna, or AstraZeneca vaccines.
While researchers suggest the Omicron variant is less virulent, it is understood to be around 70 times more transmissible than the Delta strain.
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