A man receives the COVID-19 vaccine at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

Staff members work at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

A man receives the COVID-19 vaccine at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

Staff members ask people's personal information waiting to receive the COVID-19 vaccine at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

A woman receives the COVID-19 vaccine at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

A medical worker is seen at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

People walk in and out of a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

People are seen at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

Staff members work at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)

A medical worker shows a vial of the COVID-19 vaccine at a mass vaccination venue converted from the Cairo's International Exhibition Center in Cairo, Egypt, on May 25, 2021. (Xinhua/Ahmed Gomaa)