Chinese Covid-19 vaccine efficacy is ‘not high,’ top health official admits

The efficacy of Chinese Covid-19 vaccines is “not high” and authorities are weighing options to bolster protection — including mixing different shots, China’s top disease control official has said.The efficacy of Chinese Covid-19 vaccines is “not high” and authorities are weighing options to bolster protection — including mixing different shots, China’s top disease control official has said.