Chinese vaccine developer Sinopharm said interim results from final stage trials of one of its coronavirus vaccines showed a 79 per cent efficacy rate, moving the group closer to large-scale rollout in China and overseas.

The Beijing-based branch of China National Biotec Group, a unit of Sinopharm that is developing the vaccine, published the results on its website on Wednesday. The result clears the minimum requirements for Chinese regulators and the group has applied for market approval, it added.

The same jab, one of two Covid-19 vaccines under development by Sinopharm, received approval in Bahrain and the United Arab Emirates this month, after the Gulf states separately said the vaccine had an 86 per cent efficacy rate.

Neither Sinopharm nor regulators in Bahrain and the UAE have publicly released details of the analysed data, making it unclear what accounts for the difference in reported efficacy rates. Sinopharm did not respond to a request for comment on the discrepancy.

The lack of transparency over data and regulatory approval for Chinese vaccines has caused international experts to question whether global standards are being met.

Greater openness would help mitigate the discrepancies, according to Xi Chen, an associate professor at the Yale school of medicine. Prof Chen said the discrepancies were probably due to independent clinical trials with different numbers of participants being conducted in countries at various stages of controlling the virus.

“To further secure market share, especially in some western countries, more data will have to be released,” he said, adding that the application for conditional approval from the Chinese regulator would increase Sinopharm’s reach at home and in countries where its clinical trials have been conducted.

China’s foreign ministry on Monday defended the vaccine programmes and reiterated plans to offer the jabs as a “global public good” once development had concluded.

Sinopharm’s two vaccines, both of which use a chemically inactivated version of the Sars-Cov-2 virus to spark an immune response, are leading contenders to be distributed both in China and to countries across the developing world.

More than 1m people have already received the jab within China as part of an emergency use programme that officials said would be expanded this winter to include all high-risk groups, including workers travelling overseas, healthcare professionals and the elderly, in a bid to prevent a relapse of virus transmission.

Multiple countries in the developing world have struggled to obtain vaccines from western companies including Moderna, BioNTech/Pfizer and Oxford/AstraZeneca and are likely to be reliant on vaccines from Chinese pharmaceutical groups.

The efficacy rate, if replicated in a final analysis of phase 3 results, would place the Sinopharm vaccine’s result below those of Moderna and BioNTech/Pfizer, which have achieved higher than 90 per cent efficacy.

Sinopharm, one of China’s largest vaccine manufacturers, has said it expects to be able to make 1bn doses of its two inactivated Covid-19 vaccines by the end of next year.

Sinovac and CanSino Biologics, two other Chinese pharmaceutical companies, are also developing vaccines.

Chinese vaccines can be transported at normal refrigeration temperatures, rather than the subzero conditions necessary for Moderna and BioNTech/Pfizer jabs.

China’s near complete eradication of the virus within its borders has given Chinese developers greater leeway to provide vaccines to overseas markets.

However, sporadic clusters of Covid-19 infections in China, including in Beijing and Liaoning province, could increase domestic demand and create a new “urgency to vaccinate the Chinese population, adding some uncertainties to its global market supply”, said Prof Chen.