A boy receives a dose of oral polio vaccine in the railway station in the city of Karachi, in Sindh Province. On 31 January 2011 in Pakistan, a sub-National Immunization Days (SNIDs) campaign against polio began in 56 districts, targeting 13 million children under age five. Pakistan is one of only four polio-endemic countries in the world, and the only endemic country to experience a rise in polio cases in the past year: Cases jumped from 89 in 2009 to 144 in 2010. The increased spread of polio arrived during the worst flooding in Pakistans recorded history, a crisis that affected 20 million people and destroyed health systems across the country, including the cold chain, the series of temperature controls required to maintain vaccine potency from manufacture through inoculation. Polio transmission also continues in Khyber-Pakhtunkhwa Province and the Federally Administered Tribal Areas (FATA), areas where conflict and security concerns hamper access to aid and health workers. In response, the Government, assisted by UNICEF and others, has developed a national emergency plan to put the country back on track toward polio eradication, including new oversight and accountability mechanisms. Polio-immunization staffs have also been relocated to the worst flood-affected areas to assist in recovery and to establish early warning systems for disease outbreaks. The Ministry of Health and partners are working to provide measles and polio immunizations to all children under five who have been displaced by the flood crisis. An additional polio immunization campaign began on 2 February.