This photo taken on April 10, 2021 shows a man receiving a vaccine against the Covid-19 coronavirus in Nanjing, in China's eastern Jiangsu province. - China OUT (Photo by STR / AFP) / China OUT (Photo by STR/AFP via Getty Images) BEIJING - 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.Chinese vaccines "don’t have very high protection rates," said the director of the China Centers for Disease Control, Gao Fu, at a conference Saturday in the southwestern city of Chengdu.Beijing has distributed hundreds of millions of doses abroad while trying to promote doubt about the effectiveness of.