Progress toward poliomyelitis eradication --- India, January 2009-October 2010.

India is one of only four countries (including Afghanistan, Nigeria, and Pakistan) where wild poliovirus (WPV) transmission has never been interrupted. Historically, WPV transmission in India has centered largely in Uttar Pradesh and Bihar, two states with low routine vaccination coverage, large migrant and remote populations, and lower relative vaccine effectiveness than other areas of the country. However, during a 9-month period from November 2009 to August 2010, no WPV type 1 (WPV1) cases were reported in Uttar Pradesh or Bihar. This report summarizes the substantial progress made in India toward polio eradication during January 2009-October 2010, according to data reported as of December 4, and updates previous reports. During January-October 2010, only 40 WPV cases were confirmed in India, a 94% decrease from the 626 WPV cases confirmed during the same period in 2009; the decrease likely resulted, in large part, from the introduction of bivalent oral poliovirus vaccine types 1 and 3 (bOPV). Increasingly important contributors to WPV transmission are large migrant subpopulations; surveys have indicated that up to 11% of children aged <5 years in these subpopulations were missed during supplementary immunization activities (SIAs). Interruption of all WPV transmission in India will require maintaining high levels of immunity in Uttar Pradesh and Bihar and additional efforts directed toward children in migrant subpopulations that are not vaccinated as readily during SIAs.