People line up to get vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People get vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People get vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People get vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

A woman gets vaccinated with COVID-19 vaccine in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People get vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

A man has his personal information registered before getting vaccinated with COVID-19 vaccine in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People get vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People head to observation area after getting vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)

People stay for observation after getting vaccinated with COVID-19 vaccines in Dadong District of Shenyang, northeast China's Liaoning Province, May 18, 2021. (Xinhua/Yang Qing)