A medical worker prepares a booster shot of COVID-19 vaccine at a vaccination clinic in Fanyu District of Guangzhou City, south China's Guangdong Province, Oct. 18, 2021. Guangzhou has started to give booster shots of COVID-19 vaccine to people aged over 18 who received the second dose of inactivated vaccine or the first dose of adenovirus vector vaccines at least six months ago. (Xinhua/Deng Hua)
