Children in a Lahore slum after heavy rains. The slum has a large population of Pashtuns who came from Pakistan's lawless tribal regions; many carry the polio virus with them.
An Indian child receives the oral polio vaccine. Twice a year, an army of 2 million volunteers fans out across India to administer the vaccine. India has not reported a single case of polio in more than a year-and-a-half.
A Yemeni child receives a polio vaccine in the capital city of Sanaa. The Yemen government launched an immunization campaign last month in response to the polio outbreak in neighboring Somalia.
Mohammed Huwais/AFP/Getty Images