India has reported its first case of polio but its vaccine derived polio virus (VDPV) and not caused by the wild polio virus. A five-month-old child from the Murshidabad district of West Bengal has got infected with the virus after taking the oral polio vaccine. This does not threaten India's recently awarded polio free status because though detecting VDPV is part of the surveillance system it does not get added when putting together a country's polio numbers. Only infections triggered by wild polio virus strains like P1 and P3 get counted. VDPV is caused by the vaccine given to children.