A child receives oral polio vaccine during an anti-polio campaign in northwest Pakistan's Peshawar on Aug. 26, 2019. A three-day anti-polio campaign kicked off in Pakistan's northwest Khyber Pakhtunkhwa province on Monday. (Photo: Saeed Ahmad/Xinhua)

A medical staff marks a child after giving polio vaccine during an anti-polio campaign in northwest Pakistan's Peshawar on Aug. 26, 2019. A three-day anti-polio campaign kicked off in Pakistan's northwest Khyber Pakhtunkhwa province on Monday. (Photo: Saeed Ahmad/Xinhua)

A child shows his marked finger after receiving polio vaccine during an anti-polio campaign in northwest Pakistan's Peshawar on Aug. 26, 2019. A three-day anti-polio campaign kicked off in Pakistan's northwest Khyber Pakhtunkhwa province on Monday. (Photo: Saeed Ahmad/Xinhua)