SINOVAC Biotech Ltdreleased new data that shows that 95% of individuals who have received three doses of CoronaVac® possess neutralising antibodies against Omicron.
The study, posted on bioRxiv, was conducted in China and examined the immune response of CoronaVac®, a β-propiolactone-inactivated vaccine, in 120 participants.[1]
Results from the study supported the use of a three-dose immunisation regimen as the seroconversion rates of neutralizing antibodies against Omicron jumped from 3.3% (2/60) to 95% (57/60) for two- and three-dose schedules respectively.1 In those participants who received three-doses, researchers also isolated 323 human monoclonal antibodies derived from memory B cells, half of which recognise the receptor-binding domain (RBD) and show that a subset of them (24/163) provide neutralisation of SARS-CoV-2 variants of concerns (VOCs).1
The World Health Organization (WHO) designates a variant as a VOC if it is associated with “increase in transmissibility or detrimental change in COVID-19 epidemiology, increase in virulence or change in clinical disease presentation, or decrease in the effectiveness of public health and social measures or available diagnostics, vaccines, therapeutics”.[2]
Pearson LIU, spokesperson for SINOVAC, commented, “As the world continues to combat the emergence of new COVID-19 variants, this study provides reassurance that inactivated vaccines, one of the most widely used vaccines globally, remains effective in the fight against COVID-19. The results support a three-dose immunisation regimen to ensure greater protection against COVID-19, a finding which aligns with the advice of the WHO and local health authorities around the world for all types of COVID-19 vaccines.”
These latest data come in the wake of recent findings that show one-month after the second dose, CoronaVac® elicits a significantly higher T-cell response, which is important in preventing serious illness, hospitalisation and death, compared to a mRNA vaccine.[3] The findings, which were published in December 2021, are from a study conducted by the LKS Faculty of Medicine, The University of Hong Kong (HKUMed) and the Faculty of Medicine, The Chinese University of Hong Kong (CU Medicine).