China's National Health Commission (NHC) on Wednesday announced rolling out a second round of COVID-19 vaccine booster shots for high-risk groups.

People aged over 60 or those with underlying diseases or weak immunity, who had their booster shots over six months ago, will get a second booster, according to the NHC's plan.

For the purpose, all COVID-19 vaccines approved for emergency use or those granted conditional market approval in China can be used, but a vaccine type different from the previous one inoculated is preferred.

A majority of people in China have so far received two shots and a booster, which are all inactivated vaccines from Sinopharm or Sinovac. Meanwhile, some people received three shots of recombinant protein vaccine or one shot of adenoviral vector vaccine. Besides the jabs, alternatives include inhaled or intranasal COVID-19 vaccines.

Three kinds of vaccines have been approved in China so far: inactivated vaccine, recombinant protein vaccine and adenoviral vector vaccine. Two other types China has been working on are live attenuated influenza vaccine and nucleic acid vaccine.

Stressing the importance of vaccination, the NHC has required the local health authorities and other relevant departments to closely monitor the inoculations for people's safety and encourage the targeted group to receive the booster.