As the nation is busy fighting recent COVID-19 outbreaks, mass vaccinations have kicked off in many parts of the country.

Beijing's 220 health centers have since Friday vaccinated 73,537 people, with no major side effects detected, said Gao Xiaojun, a spokesman for the Beijing Health Commission, at a news conference on Sunday.

As required by the national health authority, the first batch of vaccinations are being given to nine key groups including inspection workers handling imported cold-chain products, workers at ports of entry and those in the transportation sector. Medical and government department workers and those needing to travel abroad are also included.

Currently, health centers don't accept individual vaccination reservations. Individuals going abroad for personal reasons can apply for the shot at their residential community service centers.

Both Beijing and Shandong province plan to complete first-batch vaccinations before the Chinese Lunar New Year, which falls on Feb 12 this year.

Imported and domestic infections are being sporadically seen nationwide.

Beijing reported one domestic case, an eight-month-old girl, on Saturday. The infant is being treated in Ditan Hospital and all of her eight close contacts are under medical observation.

Her mother and grandmother were both previously reported as confirmed local cases in Shunyi district, Beijing.

In South China's Guangdong province, a B.1.1.7 imported viral mutation case was reported over the weekend.

The mutation carried from the United Kingdom by a returnee is highly similar to the gene sequence of the mutated virus recently seen in the UK, said the Guangdong Provincial Center for Disease Control and Prevention.

The Chinese mainland first detected the highly contagious variant in a woman who was tested upon arrival at an airport in Shanghai on Dec 14 after a flight from the UK.

Wang Huaqing, a chief researcher at the center, said on Sunday that regarding the viral mutation, "The World Health Organization is watching the issue closely."

Pang Xinghuo, deputy director of the Beijing Center for Disease Control and Prevention, said vaccine recipients should still follow COVID-19 preventive measures such as wearing masks and social distancing.

Also, only those aged between 18 and 59 can take the vaccine now, she added. "Pregnant and lactating women should not be vaccinated."

The health commission of Dalian, Liaoning province, said on Sunday that the latest COVID-19 outbreak in the city was started by five dockworkers unloading imported cold-chain cargo from a Russian-owned ship.

Moreover, a super spreading event involving direct and indirect transmission from one to over 30 was detected in the outbreak clusters in the Chinese port city, it added.

Since the outbreak emerged on Dec 15, Dalian reported 48 confirmed cases and 30 asymptomatic cases as of Saturday.

The National Health Commission said on Sunday that the Chinese mainland reported eight local cases on Saturday, with four in Heilongjiang province, two in Liaoning province and one each in Beijing and Hebei province.

Zhang Xiaomin in Dalian contributed to this story.