The announcement by a unit of state-owned Sinopharm gave the first official data from a Chinese vaccine’s late-stage trial. Its reported effectiveness rate is behind Pfizer Inc.’s vaccine at 95% and Moderna Inc.’s at 94%. Scientists have cautioned coronavirus vaccines may only be about as effective as flu vaccines, which generally are 50% effective.

Sinopharm is one of at least five Chinese developers that are in a global race to create vaccines for the disease that has killed more than 1.7 million people. More than 1 million health care workers and others in China have received vaccines being developed by Sinopharm and another supplier, Sinovac, under emergency approval while testing was underway.

The two-sentence statement by the Sinopharm unit that developed the vaccine, the Beijing Biological Products Institute Ltd., gave no additional details. Final proof of its effectiveness will depend on publication of more data.

“That’s useful, and at least it is showing that it is probably effective,” said Jin Dong-yan, a medical professor at the University of Hong Kong.

Jin said “it would be helpful” to know how many people were vaccinated, how large the control group was and other details.

“They should release more information,” Jin said.

Also Wednesday, another developer, Sinovac Biotech Ltd., signed an agreement to build a production facility in Beijing for a coronavirus vaccine with a planned annual capacity of 1 billion doses, the newspaper Beijing Youth News reported.