China mulls mixing vaccines to improve jabs World April 12, 2021 BEIJING: China is considering the mixing of different Covid-19 vaccines to improve the relatively low efficacy of its existing options, a top health expert has told a conference. Authorities have to "consider ways to solve the issue that efficacy rates of existing vaccines are not high", Chinese media outlet The Paper reported, citing Gao Fu, the head of the Center for Disease Control and Prevention.