A medical worker introduces precautions for the COVID-19 vaccination at Jiangxi Provincial People's Hospital in Nanchang, capital of east China's Jiangxi Province, Jan. 4, 2021. Key groups with higher risks of infection, including frontline medical workers, customs inspectors of imported cold-chain goods and personnel working in the overseas and domestic transportation sector, began to receive their first COVID-19 vaccine doses in Jiangxi Province. (Xinhua/Peng Zhaozhi)