Sinovac Biotech’s experimental Covid-19 vaccine CoronaVac has triggered a quick immune response but the level of antibodies produced was lower than in people who had recovered from the disease, preliminary trial results showed.

The study comes hot on the heels of upbeat news this month from United States drugmakers Pfizer and Moderna, as well as Russia that showed their experimental vaccines, were over 90 per cent effective based on interim data from large, late-stage trials.

The Sinovac findings, published in a peer-reviewed paper in medical journal The Lancet Infectious Diseases, came from results in phase 1 and phase 2 clinical trials in China involving more than 700 participants.

“Our findings show that CoronaVac is capable of inducing a quick antibody response within four weeks of immunisation by giving two doses of the vaccine at a 14-day interval,” Zhu Fengcai, one of the authors of the paper, said.