A drive to vaccinate 60 million African children against polio was under way last month, part of the latest immunization campaigns that have reduced the number of polio-endemic countries in Africa to an all-time low, according to the World Health Organization. Only three African countries—Nigeria, Niger, and Somalia—are considered polio-endemic, compared with 20 in 1999.
A global effort launched in 1988 to eradicate polio has reduced the number of cases by 99%. But experts warn that eliminating the final 1% will entail many difficulties, including reaching children in remote areas and in conflict-affected countries.
Stephenson J. Push to End Polio. JAMA. 2002;288(22):2813. doi:10.1001/jama.288.22.2813-JWM20012-2-1