Sinovac's booster enhances protection against COVID-19

SHANGHAI: According to researchers, a larger interval between the second and third doses of China's Sinovac COVID-19 vaccination gives better immunity against the virus than a shorter gap.

According to investigators from Sinovac Biotech, Fudan University, and several regional Centers for Disease Control and Prevention, antibody levels in people who received the third dose eight months after their second dose rose more than twice as much as those who received a booster shot within two months of their second dose.

Research further highlighted that immunity from COVID-19 had significantly diminished after six months of two doses of the vaccine, also known as CoronaVac. The third dosage at eight months culminated in a remarkable increase in antibody levels.

A two-dose regimen of CoronaVac was proven to produce strong immunological memory in an investigation. Although neutralising antibody levels fell to near or below the lower limit of seropositivity 6 months following the second dosage, a third dose given 8 months later was highly successful in reactivating a SARS-CoV-2-specific immune response resulting in a considerable rebound in antibody levels. The findings concluded that a single homologous booster dosage might give longer-lasting immunity and better protection than a two-dose regimen.

The research 'Immunogenicity and safety of a third dose of CoronaVac, and immune persistence of a two-dose schedule, in healthy adults: interim results from two single-centre, double-blind, randomised, placebo-controlled phase 2 clinical trials' has been published in The Lancet.