“The relevant data will be released to the public in time after unblinding [the double-blind, placebo-controlled phase 3 trial],” Zheng told reporters at a briefing on Saturday.

“If the data meets the relevant requirements, China’s drug regulatory authority will issue approval for market launch, or launch with conditions,” he said.

A document issued last month by the Centre for Drug Evaluation allows “innovative vaccines” to be approved for conditional market launch based on the interim results of their phase 3 trials.

Although the Chinese products were among the first in the world to enter final stage human trials, they subsequently made slower progress, partly due to the lack of infections in the areas in which they were tested, namely, the Middle East, South America and Asia.

The results of the phase 3 trial of Chinese firm Sinovac’s product, which was tested in Brazil, will be released on Wednesday, according to local media reports.

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Two vaccines produced by CNBG and one developed by Sionovac have been authorised for emergency use since the end of July, with 1 million Chinese already receiving them, Zheng said.

Zeng Yixin, deputy director of the NHC, said at the press briefing that the inoculation programme for key groups was intended to help prevent imported cases and fresh local outbreaks, even though China has largely contained the Covid-19 epidemic.

The key groups included those working in the health care, aviation and public transport sectors, at markets, and where chilled and frozen foods were handled and processed, Zeng said, without saying what numbers would be involved.

A teleconference held earlier in the week also identified people travelling abroad, and those working in the utility, logistics and elderly care sectors as being the priorities for inoculation.

The Chinese Centre for Disease Control and Prevention estimates that about 18.5 million workers at high risk of infection and nearly 31 million others, in jobs essential to a fully functioning society, were most in need of a vaccine.

Cui said inoculating key groups would reduce the chances of local outbreaks sparked by imported cases, while a wider vaccination programme for the general public following the “conditional approval of vaccines or the gradual increase in vaccine production” would help to build herd immunity.

“Through the orderly implementation of vaccinations, eligible people can be inoculated and an immune barrier among the population will gradually be built to block the spread of the new coronavirus,” he said.

Cambodia ‘not shunning’ Chinese vaccines

Although the three vaccines produced by CNBG and Sinovac were approved for emergency use after the completion of only early phase trials involving low numbers of subjects, China’s health officials said they had been used to inoculate more than 1 million people and proved to be safe.

The adverse events recorded in recent months were “less severe” than those found in foreign countries, according to Jiao Yahui, deputy director of the NHC’s medical administration bureau.

“The common adverse events included headache, fever, redness or lump on the injection site. Some developed adverse events like cough, loss of, vomit or diarrhoea,” she said.

All of the clinics where the mass inoculation would take place would have to have the ability to deal with any severe adverse events, she said.