BEIJING : Researchers plan to start a clinical trial for an additional dose of a coronavirus vaccine candidate co-developed by China's CanSino Biologics Inc and a military-backed research unit, clinical trial registry data showed.A single dose of the vaccine candidate Ad5-nCoV, one among a handful that China is pursuing, has final-stage trials lined up in Pakistan and Russia.
The candidate has been approved for use in the Chinese military.Scientists outside the company have expressed concern that the effectiveness of Ad5-nCoV, which uses a common cold virus many people have contracted to carry genetic traces of the coronavirus, could be limited.In response, CanSino said earlier this month there was no evidence that existing immunity against.