In an alarming development, the first-ever case of vaccine-derived polio virus Type 2 has been reported from Uttar Pradesh. The news comes at a time when the Government was planning to do away with administration of trivalent vaccine in the state because of the absence of Type 2 polio virus.

The latest report of the National Polio Surveillance Project says an 11-month-old boy from Badaun district has been confirmed to have vaccine-derived polio virus Type 2.

The last carrier of wild polio virus Type 2 was reported in October 1999 in Uttar Pradesh, and though the new case is believed to be vaccine-derived, experts are not taking any chances.

It is the fourth case of vaccine-derived virus in India, and the third case involving Type 2 polio. None of the cases is related to each other.

With Badaun district being the epicentre of the polio virus in the country, the Uttar Pradesh government has rushed a team of doctors to the spot to conduct sampling. Dr R R Bharti, the Director General, Medical and Health, Uttar Pradesh, said they were planning a special drive for the area with trivalent vaccine (for Types 1, 2 and 3).

Vaccine-derived polio viruses are strains which emerge from live virus contained in the oral polio vaccine (OPV) given to children. In rare cases, these lead to polio in children with immunodeficiency or living in a population with very low immunity.