Beijing is set to expand a programme that administers experimental coronavirus vaccines as chinese developers chart a risky path to dominating global supplies.

In a surprise announcement last month, a representative from state-owned china national biotec group, or sinopharm, revealed that hundreds of thousands of chinese had already taken the companys two leading experimental covid-19 vaccines.

The drugs were dispensed as part of a limited use programme that began with little fanfare by the chinese government in july. the vaccines were administered even though final stage, or phase 3, trials designed to confirm overall effectiveness had not been completed.

Details of the programmes scope remain unclear, but government statements suggest use was originally restricted to frontline health workers and state employees travelling overseas to high-risk areas, including to work on projects along chinas belt and road infrastructure investment scheme.

The programme now appears to be expanding to include large portions of the population, in what experts said was a high-risk strategy for vaccine developers to distribute and test products before they hit global markets.

Health authorities in one chinese province have asked enterprises and government departments to gather details of employees willing to receive emergency use vaccines ahead of winter, according to a government notice issued last month seen by the financial times.

Apart from health workers and other target groups guaranteed to get vaccines, the document, which has not been made public, also had a long list of additional target suggested recipients.

Included among the recipients were transport workers, people travelling to countries with high covid-19 infection rates, frozen food logistics workers, staff in supermarkets or other enclosed spaces, and employees of schools, orphanages, jails and elderly care homes.

After the vaccine was administered, tests for adverse events following immunisation should be conducted.

When qin xin, an employee at a state-owned financial institution, saw the offer to receive a covid-19 vaccine in her work wechat group, she assumed the message had been sent in error.

I didnt think about it much, just thought that sooner or later i would have to be inoculated, she told, a popular online media outlet.

Ms qin said she had felt an inexplicable heat on the first night but returned to normal by the second day after taking the shot. i think that if the nation is willing to let normal people take it, then the side effects cant be all that bad.

Chinese health officials have defended their decision to distribute the vaccine, saying the move was sanctioned by the world health organization.

But the scale and opacity of chinas programme have raised safety and ethical concerns from medical experts, especially given chinas claims that it had halted almost entirely transmission of the virus within its borders.

Arthur caplan, professor of bioethics at new york university langone medical center, said china appeared to be acting irresponsibly by stretching the definition of emergency use beyond previous applications.

Historically, approval for emergency use was given for vaccines that had a record, perhaps in other countries, and was used on a focused population, such as a college campus, during an emergency with imminent deaths.

Chinas approach, according to mr caplan, was closer to throwing something up against the wall to see what sticks.

We need to go quickly, but there is no point in going so quickly that we cant answer basic questions about safety and efficacy, he said.

Jerome kim, director-general of the international vaccine institute in seoul, said the overall risks for the programme would hinge on whether high standards of consent, data collection and follow-up testing were applied. the drug companies have not made those details public.

If you are sending workers off to, say, africa how would you know if they have a side effect outside of china? he asked.

Last month, during a government-organised tour of sinovac, chief executive yin weidong said the company had provided tens of thousands of doses of its vaccine to the beijing government for emergency use.

Sinovac and sinopharm along with cansino biologics, which has developed a common cold virus-vectored vaccine with chinas military are the countrys best contenders to corner a portion of the vast global demand for immunising shots designed to slow the spread of sar-cov-2, the virus that causes covid-19. the disease has killed more than 1m people worldwide.

This month, the united arab emirates became the first foreign country to approve a chinese vaccine from sinopharm for limited use.

Owing to the lack of positive cases in china, its vaccine developers have been forced to carry out phase 3 trials overseas and some of these agreements include pledges to distribute vaccines in the host country. sinovac, for example, has promised to supply 40m vaccines to indonesia by march 2021.

Chinas health officials reckon the country will be able to produce more than 600m doses of vaccines by the end of this year and 1bn by the end of next year.

Mr yin told reporters that sinovac had begun developing its drug with a strategy designed for china. but after the country controlled the spread of the virus, its goal became to provide the vaccine to the world.