JINAN -- A total of 217,158 doses of COVID-19 vaccines have been administered to key groups with higher risks of infection in East China's Shandong province, authorities said on Monday.

As of Sunday, no serious side effects have been reported among vaccine recipients, said the provincial health commission.

Related personnel in port cities are prioritized for inoculation.

China in mid-December officially launched a vaccination program for the winter-spring period targeting several key groups. These groups include those engaged in the handling of imported cold-chain products, customs officers, medical workers, and people working in public transport and fresh produce markets.

"I used to be worried about being infected with the virus as I'm in the cold-chain business. The vaccination has comforted me," said Xia Dongdong, a cold-chain food processing worker at a food company called Tanrun based in Tancheng county in the city of Linyi.

"I've had no adverse reactions," he said.

According to the commission, frontline customs inspectors involved in the import of frozen goods and loading and transporting personnel working at ports have received their first vaccine doses.