A child getting a polio vaccine at Toll Plaza, outskirts of Karachi. Polio is a highly infectious disease caused by a virus that can provoke permanent paralysis in a matter of hours. There is no cure, but there are safe and effective vaccines.
Saurabh Das / AP
A child is administered polio drops by a mobile unit during an anti-polio drive in New Delhi, India, Sunday, Jan. 15, 2012. India marked a full year since its last reported case of polio on Friday, Jan. 13.
Chris Hondros / Getty
A Nigerian schoolboy is vaccinated against polio during a mass nationwide polio inoculation April 12, 2005, in Kano, Nigeria.
JAGADEESH NV / REUTERS
A ten-year-old polio victim in Bangalore, India
Bill Gates gives a baby an oral polio drop at a community health clinic in Andhra Pradesh
CHRIS HONDROS / GETTY
POLIO: After a year-long hiatus, children in Nigeria are once again getting oral vaccines
Chris Hondros / Getty Images
Teams Give Polio Vaccine in Massive Nigerian Innoculation
Fayaz Aziz / Reuters
An Afghan refugee woman waits her turn to receive a drop of polio vaccine for her child at the United Nations High Commissioner for Refugees supported Jalozai camp on the outskirts of Peshawar, Sept. 25, 2012.