China is accelerating research and development of COVID-19 vaccines targeting the Omicron variant, a health official said on Thursday, amid concerns among global scientists that it may spread more quickly than other strains. Mainland China has not detected any Omicron case yet.

"We are rapidly pushing forward the research and development of Omicron-specific vaccines based on different technologies," Zheng Zhongwei, who heads a group tasked with COVID-19 vaccine development in China, told state broadcaster CCTV.

The potential vaccines against Omicron, dubbed a "variant of concern" by the World Health Organization, might not eventually be used but it was necessary for China to make such preparation, Zheng said.

There is no firm evidence yet whether Omicron will evade the vaccine-induced immunity, but most existing shots are still expected to help reduce severe disease and death, he added.

Chinese vaccine maker Sinovac Biotech said it was evaluating whether its vaccines work against Omicron or whether the company needs to develop new ones.

Shenzhen Kangtai Biological Products (BioKangtai) was seeking to cooperate with other institutions on vaccine research related to Omicron.

BioNTech SE expects more data on the Omicron variant within two weeks to help determine whether its vaccine produced with partner Pfizer Inc would have to be reworked, its chief executive said on Tuesday.

China has yet to approve COVID-19 vaccines developed overseas and uses several home-grown shots for its inoculation program.