China says it has been ramping up coronavirus vaccinations amid the spread of mutant strains that have been driving recent rebounds.

Nearly 640 million doses of COVID-19 vaccines have been administered in China. The daily inoculation rate has been over 2.5 times that of a month before – with an average rollout of 12 million doses per day, health officials said at a press conference in Beijing on Monday.

China's vaccination work is moving fast, but there's still a considerable way to go before herd immunity, they said.

Recent flare-ups have been triggered by coronavirus variants first found abroad, which have higher transmission rates than older strains. China will step up the prevention of epidemic rebound and imported COVID-19 cases.

"We have to continue improving our monitoring and detection capabilities. We must adopt more stringent protective measures in areas that are at high risk of infection, such as medical institutions, designated hospitals and isolation facilities for those returning from abroad," said Feng Zijian, a senior researcher at the Chinese Center for Disease Control and Prevention (CDC).

Chinese vaccines effective against variants first detected in the UK and South Africa

Vaccine developers have already been working on vaccines that can work against virus mutations.

Zhang Yuntao, vice president of Sinopharm's CNGB, said the company's COVID-19 vaccines show efficacy against new strains first found in the UK and South Africa.

"Vaccines against new strains can be quickly developed. They can be used in sequence with existing jabs as a multivalent vaccine. Throughout the years, we have developed better processes for vaccine supervision, review and approval. We've streamlined the overall process for the development and quality assurance of our vaccines," Zhang explained.

Shao Yiming, another CDC expert, said China is also better equipped with the addition of other vaccines to its list of COVID-19 jabs for emergency use, including a recombinant protein subunit vaccine and two more inactivated vaccines.