The polio eradication campaign is the largest non-military, global enterprise in history. It involves dozens of organizations, scores of governments, thousands of health workers and millions of volunteers. In a world of AIDS, malaria and other health crises, the eradication of polio would demonstrate that humankind can triumph over nature. After sixteen years of the campaign in India, on February 25th, 2011 India has finally been declared polio free with the last polio case dated January 13th, 2010. The size of the campaign in India is nothing less than amazing; 2.3m vaccinators and 155,000 supervisors go house to house to 209 million houses and vaccinate 172m kids under 5 years old twice a year during the national immunization day (NID). A sub-national immunization day takes place up to eight times a year in high risk areas like Uttar Pradesh and Bihar where more than 550,000 new babies are born every month. The following gallery is a documentation of the Sub National Immunization Day (SNID) in Bihar commissioned by UNICEF as a part of the last documentation of the program in India. The images will be published in the book 'The SNID' that is scheduled for publication on February 2013.