BEIJING -- Studies by Chinese teams on vaccines against COVID-19 variants started a long time ago, a leading Chinese medical scientist has said.

"By running extended targeted studies via national databases, we have been tracking the safety of vaccines in the long term, and tracking the vaccine's efficacy rate against the latest mutations," Chen Wei, a researcher at the Institute of Military Medicine under the Academy of Military Sciences, on Saturday told the China Central Television.

"We have been tracking and analysing a global database of COVID-19 patients with more than 400,000 samples through genetics and biologics. Our labs then cross-examine the responses of virus variants detected in, for example, Brazil, South Africa and Britain, to existing vaccines," Chen said.

"We have launched studies a long time ago in search for new vaccines targeting mutations," she said, adding that their studies will not end "in order to be prepared enough."