More than 510 million doses of COVID-19 vaccines have been administered across China as of Sunday, the National Health Commission (NHC) said Monday.

The pace of inoculations has accelerated after fresh locally-transmitted cases were reported in several places across China since May 13.

The country's vaccine production capacity is also growing quickly, meeting the domestic demand of over 20 million doses per day, the NHC said.

Among the recently confirmed cases in China, some were found to have been infected with variants circulating in other countries.

The Chinese Center for Disease Control and Prevention (CDC) said that COVID-19 vaccines currently used in China are still effective against variants detected in other countries based on preliminary research results.

Shao Yiming, chief expert at the CDC, said that once the existing jabs become ineffective against new COVID-19 strains, China can swiftly adjust and manufacture its inactivated vaccines as the entire production process doesn't require any major adjustments.

Read more: China can adjust its COVID-19 vaccines swiftly against emerging variants