Zero dose of polio vaccine in which is give
Before giving DPT
At bih
When child is having diarrhoea
When child is having polio
the WHO programme on immunisation and the national immunisation programme in india recommend a primary course of 3 doses of OPV at one month intervals,commencing the first dose when infant is 6 weeks old.it is recommended that a dose of OPV (zero dose)is required to be given to all children delivered in health institutions before their discharge from hospital. ref:parks textbook ,22nd edition,pg no 187
Epidemiology