Sinovac Biotech said on Saturday that its unit's Covid-19 vaccine has been approved for use by the general public by China's medical products regulator.

It marks the second vaccine approved for public use in China, after one developed by a Beijing institute affiliated with state-owned China National Pharmaceutical Group (Sinopharm) was approved in December.

Both vaccines, as well as a third candidate from Sinopharm, have already been used in China's vaccination programme which has administered over 31 million doses, mainly targeting groups at higher infection risk.

A fourth candidate from CanSino Biologics is being used among military personnel.

Indonesia, Turkey, Brazil, Chile, Colombia, Uruguay, and Laos have granted emergency authorisation for the CoronaVac vaccine developed by Sinovac Life Sciences, Sinovac said in a news release.

Approval of the two-dose regimen by China's National Medical Products Administration is based on results from two months of late-stage clinical trials overseas, from which the final analysis data has not yet been obtained, Sinovac said.

Its Beijing-based unit Sinovac Life Sciences is expected to be able to produce over 1 billion doses per year in the form of bulk ingredient by February, it said.

Sinovac is also expanding its capacity to fill vaccine into vials and syringes, which currently lags its vaccine manufacturing capacity. It has also outsourced filling and finishing procedures to overseas partners.

China plans to provide 10 million vaccine doses to COVAX, a World Health Organisation-backed global vaccine-sharing initiative that Sinovac, Sinopharm and CanSino have applied to join, the foreign ministry has said.

A Phase I and II trial in China showed the vaccine could safely trigger immune response for older participants and it is also being tested in participants aged three to 17.

Sinovac cautioned, however, that data for the protection rate among people aged 60 and above was “limited”.

“When the relevant institutions [...] use this vaccine, the necessity of inoculating this product should be evaluated in consideration of the health status and exposure risk of this age group,” it added.

Varied efficacy rates

Sinovac's vaccine is being tested in Phase III clinical trials in countries including Brazil, Turkey and Indonesia, where varied efficacy readings had been released separately, without sufficient details made available to public.

The vaccine was found 50.65 per cent effective against Covid-19 disease in the Brazil trial which had recruited 12,396 medical workers older than 18 as of December 16 and recorded 253 cases, Sinovac said in a statement on Friday.

The success rate from the Turkey trial was 91.25pc, local researchers said, based on a preliminary analysis of 29 cases. There was a 65.3pc efficacy rate in the Indonesia trial.

Brazil's more rampant epidemic, and the trial's focus on medical workers, are among factors which Sinovac believe may have lowered the efficacy rate seen in data from there, a person familiar with the matter told Reuters last month.

The Brazil trial also found the vaccine was 83.7pc effective against the disease that requires medical treatment, and 100pc effective against hospitalisation, severe cases and death in the same trial, Sinovac said on Friday.

The protection rate was nearly 70pc based on observation of a smaller sub-group in the Brazil trial, in which participants received the two doses at a three-week interval rather than two weeks apart for most participants, Sinovac said last month.