Hong Kong wants more information on the Covid-19 vaccines produced by Sinovac, before recommending the mainland China provider’s doses be used in the city’s free jabs programme.

Despite believing the vaccine to be safe, the city’s advisory panel still had questions after a three-hour discussion on Wednesday over new data provided by the Coronavac manufacturer.

Panel chairman Professor Wallace Lau Chak-sing said the group would meet again in two weeks’ time.

“After a long discussion, we believe the vaccine is safe and effective according to its data in the first and second stages,” Lau said.

Lau also said the panel had assessed phase-three clinical trials of the vaccines in Brazil, Turkey, and Indonesia and was satisfied with its effectiveness.

“The panel is of the view that the phase-three data presented showed the vaccine is effective. And in terms of safety of the vaccine, we feel that it is acceptable and the safety level is also high,” Lau said.

But he said the panel wanted answers on the difference in the results of injecting the second dose 14 days or 28 days after the first one, and whether antibodies would be created after the injection.

Lau said the panel hoped the manufacturer could provide data to answer these two questions in two weeks.

It was not immediately known if the panel’s decision would delay the city’s vaccination programme. But Lau said the group appreciated that the Lunar New Year holiday was approaching and it hoped to allow Sinovac reasonable time to provide additional information.

Lau would not say what might happen if that data was not provided in time.

Asked whether any delay would hamper the government’s vaccine scheme and affect the city’s pandemic control, Secretary for Food and Health Professor Sophia Chan Siu-chee said her bureau would have to wait for the panel to reach a definitive decision on the vaccine.

“The data provided is positive, and at the same time, they would like to see more data to make their final decision,” she said. “So, I think once we receive their recommendation, we, the Food and Health Bureau, will try our best to review and endorse the vaccines for emergency use.”

Respiratory medicine specialist Dr Leung Chi-chiu believed as long as Sinovac could provide the additional required data before the panel’s next meeting, it would not create too much uncertainty in the schedule for mass vaccination in Hong Kong.

“The question is what kinds of data they can provide, and whether the expert panel would be satisfied with what they are able to present,” he said.

Details about the difference in time between the first and second injections, and the antibodies created would be important for the decision, he said,especially when deciding on how long after the first jab people got the second dose, and whether that would be different for high-risk groups.

The panel previously asked Sinovac to provide relevant clinical data after it had been published in medical journals, but has now accepted phase-three data submitted to the World Health Organization because of time constraints cited by the manufacturer.

On Tuesday, Chief Executive Carrie Lam Cheng Yuet-ngor said her administration was following the city’s regulations, which allowed for approval of a vaccine without the final round of clinical data.

Asked if the panel felt pressured by Lam’s remarks, Lau said it made assessments based on science, an approach unanimously backed by all members.

“The decision that I have just announced has been arrived at by the whole panel, all 12 members agreed on the approach that I have just highlighted,” Lau said.

“I hope the public will not only consider whether the data has been published in a medical journal. I hope they have confidence in the 12 members of our expert panel,” he added. “We adopted the same way of reviewing a report to be published in a medical journal.”

Hong Kong expects its first batch of 1 million doses of the Pfizer-BioNTech vaccine by late February, and the government also bought a vaccine jointly developed by British-Swedish pharmaceutical firm AstraZeneca and the University of Oxford.

Last month, Lam revealed she had asked for the central government’s help in procuring a fourth vaccine.