Positive progress has been made in the development of monovalent and multivalent vaccines against the Omicron variants, a senior Chinese health official told a press conference on Saturday.

Pre-clinical studies for some vaccines have been completed, with applications for clinical trials in progress, said Zheng Zhongwei, an official with the National Health Commission.

"Studies show that the Omicron variant has not completely escaped the existing vaccines," Zheng said, noting that complete vaccination is still effective in reducing the risk of hospitalization, severe illness and death caused by Omicron variants.

"Booster vaccination can also effectively reduce the risk of breakthrough infection caused by the Omicron variant," he said.

At present, China has 29 vaccines that have entered clinical trials, with 16 under phase-III clinical trials overseas, Zheng said. He added that seven vaccines have been approved for conditional marketing or emergency use, and two have been included in the World Health Organization emergency use list.