Why polio has not been eradicated in India despite many remedial interventions?

Oral polio vaccine has reduced the incidence of polio in India and many states have been polio free for a long time while occasional polio cases are occurring in some states. On the other hand more than 96% of polio cases being reported in India are occurring in Uttar Pradesh and Bihar. The current polio scenario indicates that oral polio vaccines cannot eradicate polio from Uttar Pradesh and Bihar because some children from these two states show poor response to OPV. There is an urgent need for re-appraisal of polio eradication strategy.