A health worker gives polio vaccine to a child during a door-to-door polio vaccination campaign in Rawalpindi of Pakistan's east Punjab province on Sept. 22, 2020. A new round of nationwide anti-polio campaign kicked off from Monday with the aim of reaching 40 million children across the country with the polio vaccine, according to a press release on the website of the Pakistan Polio Eradication Program. (Xinhua/Ahmad Kamal)

A health worker gives polio vaccine to a child during a door-to-door polio vaccination campaign in Rawalpindi of Pakistan's east Punjab province on Sept. 22, 2020. A new round of nationwide anti-polio campaign kicked off from Monday with the aim of reaching 40 million children across the country with the polio vaccine, according to a press release on the website of the Pakistan Polio Eradication Program. (Xinhua/Ahmad Kamal)

A health worker gives polio vaccine to a child during a door-to-door polio vaccination campaign in Rawalpindi of Pakistan's east Punjab province on Sept. 22, 2020. A new round of nationwide anti-polio campaign kicked off from Monday with the aim of reaching 40 million children across the country with the polio vaccine, according to a press release on the website of the Pakistan Polio Eradication Program. (Xinhua/Ahmad Kamal)

A health worker gives polio vaccine to a child during a door-to-door polio vaccination campaign in Rawalpindi of Pakistan's east Punjab province on Sept. 22, 2020. A new round of nationwide anti-polio campaign kicked off from Monday with the aim of reaching 40 million children across the country with the polio vaccine, according to a press release on the website of the Pakistan Polio Eradication Program. (Xinhua/Ahmad Kamal)

A health worker marks the finger of a child after giving polio vaccine during a door-to-door polio vaccination campaign in Rawalpindi of Pakistan's east Punjab province on Sept. 22, 2020. A new round of nationwide anti-polio campaign kicked off from Monday with the aim of reaching 40 million children across the country with the polio vaccine, according to a press release on the website of the Pakistan Polio Eradication Program. (Xinhua/Ahmad Kamal)

Health workers wearing face masks walk on a street during a door-to-door polio vaccination campaign in Rawalpindi of Pakistan's east Punjab province on Sept. 22, 2020. A new round of nationwide anti-polio campaign kicked off from Monday with the aim of reaching 40 million children across the country with the polio vaccine, according to a press release on the website of the Pakistan Polio Eradication Program. (Xinhua/Ahmad Kamal)