Third shot of Sinovac COVID-19 vaccine gives big boost to immunity: study

BEIJING -- A third shot of Sinovac COVID-19 vaccine administered six months or more after the second dose will give a remarkable boost to people's immunity against the deadly virus, a new study has found.

The study was published on Medrxiv.org on Sunday for peer review.

Chinese researchers inoculated over 500 participants with a third dose six to eight months after their second jabs, and they found that the additional shot will lead to a big increase in antibody levels, with geometric mean titers assessed 14 days later increasing to 137.9, or approximately three-fold.

The study also found that although neutralizing antibody levels declined six months after two Sinovac shots, a two-dose schedule generates good immune memory.

The research is consistent with recent studies over booster immunization with the AstraZeneca vaccine, which have showed higher concentrations of total antibodies after a third dose.