CanSinoBIO mulls booster shots to ensure long-term Covid-19 immunity

China's CanSino Biologics Inc said the efficacy rate for its single-dose Covid-19 vaccine may fall over time although it should still have a rate of 50 percent or more five to six months after inoculation.

A second shot given to trial participants six months after their first injection could offer substantial protection, Zhu Tao, CanSinoBIO's chief scientific officer, said in an online presentation last night.