An affiliate of China's state-owned drug maker Sinopharm said on Wednesday its Covid-19 vaccine showed 79.34% efficacy and it has requested regulatory approval of the shot, moving a step closer to become China's first approved vaccine for general public use.
The efficacy rate, based on an interim analysis of Phase III clinical trials, is lower than 86% rate for the same vaccine announced by the United Arab Emirates on Dec. 9, based on preliminary data from trials there.
A spokeswoman declined to explain the discrepancy and said detailed results would be released later, without giving a timeline.
There have been fragmentary releases of efficacy data for Chinese vaccine makers' Covid-19 candidates, which are being considered by many developing countries for mass inoculation campaigns.
Health experts warn that piecemeal data without sufficient detail could undermine confidence in vaccines.
Turkish researchers said on Thursday their interim results from a Covid-19 vaccine developed by China's Sinovac Biotech showed 91.25% efficacy, only to see a confusing readout the same day from Brazil, which said the vaccine's efficacy was between 50% and 90%.
While the efficacy of the China-developed shots trails the more than 90% success rate of rival vaccines from Pfizer Inc and its partner BioNTech SE and Moderna Inc , it points to progress China has made in the global race to develop successful Covid-19 vaccines.
China, whose President Xi Jinping has pledged to make its vaccines a global public good, has won several large supply deals with countries including Indonesia and Brazil - the most populous countries in Southeast Asia and Latin America respectively.
But none of the Chinese drug makers has yet to release detailed efficacy data.
"I think it's very positive news. The results for other Covid vaccines ... were also released initially in very short press releases, and within a few weeks more details were provided," said Benjamin Cowling, a public health professor at the University of Hong Kong.
Experts warned, however, that it's still early to conclude how successful the Sinopharm vaccine is.
"Data can only be interpreted when key details, such as the study design, number of participants, period of observation and number of cases, are described," said Ooi Eng Eong, an immunology professor at the National University of Singapore.
The Sinopharm vaccine is among the five most advanced candidates from China in terms of development and has been used in its emergency use programme that has vaccinated hundreds of thousands of people since July.
Its developer Beijing Biological Products Institute, a unit of Sinopharm subsidiary China National Biotec Group (CNBG), said that it had applied to the National Medical Products Administration for conditional approval of the vaccine.
CNBG has another vaccine in late-stage trials and both have been approved for emergency use in China even as studies have not been completed.
The approval request in China came as Britain on Wednesday approved a second Covid-19 vaccine, a shot developed by Oxford University and AstraZeneca, as the country battles a major winter surge driven by a new variant of the virus.