Top official admits Chinese vaccines have low effectiveness PTI Beijing | Updated on April 12, 2021 Health care workers receive a dose of the Sinovac's coronavirus vaccine, after Brazil health regulator Anvisa approved its emergency use at Hospital das Clinicas in Sao Paulo, - REUTERS Health care workers receive a dose of the Sinovac's coronavirus vaccine, after Brazil health regulator Anvisa approved its emergency use at Hospital das Clinicas in Sao Paulo, - REUTERS× RELATED ‘Developers are working on mRNA-based vaccines’ In a rare admission of the weakness of Chinese coronavirus vaccines, the country's top disease control official says their effectiveness is low and the government is considering mixing them to get a boost.