Unlike their Western competitors, the Chinese companies have not disclosed data from late-stage clinical trials that would show whether their vaccines are effective, and regulators in China have not officially approved them.
That has not deterred local governments across the country, which have begun an ambitious vaccination campaign. The goal is to inoculate 50 million people - roughly the population of Colombia - by the middle of February, before the Chinese New Year holiday, when hundreds of millions of people are expected to travel.
China, where the virus first emerged a year ago, is going to great - and scientifically unorthodox - lengths to prevent a resurgence of the outbreak. While Beijing has not officially announced the vaccine target, the government has signalled the roll-out will be managed in much the same way as the outbreak, through a top-down approach that can mobilise thousands of workers to produce, ship and administer the shots.