Beijing has vaccinated 73,537 people in the two days since it started mass immunization work on Friday and no serious adverse reactions have been observed, a senior official of the city government said at a news conference on Sunday.

Starting on Friday, 220 medical service centers in the city started to be used as spots for vaccination, according to Gao Xiaojun, a spokesman for the Beijing Health Commission.

He said at present, the medical centers don't accept individual reservations for vaccination.

The first batch of vaccines will be given to nine key groups, including inspection workers dealing with imported cold-chain products, porters at entry ports and those who work in the industries of international and domestic transportation.

People who will travel abroad for work and personal reasons, medical workers and government department workers are also included.

People who need to go abroad should bring their related documents to residential communities for approval before getting vaccinated.

Pang Xinghuo, deputy head of the Beijing Center for Disease Control and Prevention, reminded people who have received a vaccine should still follow COVID-19 control and prevention measures such as a one-meter social distance and mask-wearing.

By Sunday, Beijing government has held 200 news conferences for epidemic control and prevention since the first one was held at the beginning of last year.