“I don’t want to be a lab rat.”

Zhang said it would be better to wait for the results of vaccine trials.

“I haven’t seen any peer-reviewed phase 3 data yet. Besides, China is very strict about epidemic controls and Anshan has not had a case for months. There is time to wait and see,” he said, adding that his opinion was shared by many of his colleagues.

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These groups include port workers, cold-chain food handlers and transport staff; and together they could number as many as 50 million, according to the National Health Commission.

Wang Huaqing, an immunisation expert with Chinese Centre for Disease Control and Prevention, said on Monday that the strategy could buy China time before vaccine production could be scaled up and doses approved and distributed for general use.

“At present, the vast majority of people in our country are susceptible to Covid-19. We all look forward to preventing it through vaccination,” Wang said.

“Inoculating key groups of population can minimise the risk of contracting and transmitting the virus among the key populations, providing a time buffer for subsequent vaccination of other groups of population.”

01:56

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Meet scientist Katalin Kariko, whose work was critical for Covid-19 vaccines by Pfizer and Moderna

Despite limited publicly available information, more than a million people in China have already had the shots under an emergency use scheme and the injections are in demand among others wanting to head overseas.

But those staying in the country do not seem in a hurry.

At the Sanyuanli food market in Beijing, a butcher who would only identify herself by her family name Feng said she was not convinced that she had to take it just yet.

“The market has asked us to sign up to take the vaccines but I am not sure about it,” Feng said.

“What’s the rush? We are doing fine here without vaccines.”

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Markets are seen as high infection risk areas because of the crowds they attract and the frozen food they sell. The management of the Sanyuanli market has stepped up measures to check each customer’s temperature, register their health information and constantly remind them to wear masks through broadcast.

The market’s variety of imported food also makes it a popular spot with expatriates but Feng was not so concerned about the risk of imported cases.

“There are fewer foreigners here this year. Also, because China has been very strict with border control, most of the customers never left the country,” she said.

01:56

First Covid-19 vaccine administered as US death toll passes 300,000

First Covid-19 vaccine administered as US death toll passes 300,000

But in central China, Zhu Junqiang, a sales manager at a frozen meat importer in Wuhan, where the coronavirus was first detected, welcomed any potential protection from the pathogen.

“Workers are tested for the coronavirus at least three times a month and they wear protective suits, but that is not enough,” Zhu said.

“It’s hard labour for workers and they can’t wear masks or protective suits properly for long hours. Vaccines are much better.”

Zhu said he was aware that China has not approved any vaccine for general use and no peer-reviewed trial data has been released, but “any level of protection is better than no protection at all”.

He also hoped the vaccines could be supplied free but he was willing to pay the roughly 200 yuan (US$30.50) per dose that some candidates are understood to be sold for.

“I don’t want to risk my health or even my life over a small matter like a few hundred yuan,” he said.