The characteristics of polio vaccine are all except?

Ans. is 'b' i.e., 100% immunization In OPV, the viruses multiply in the gut and the vaccine progency is excreted in the feces and secondary spread occurs to house hold contacts and susceptible contacts in the community. Non-immunized person may therefore, be immunized. Thus widespread herd immunity results, even if only approximately 66% of the community is immunized (100% coverage is not required). Advantages of OPV o Easy to administer o Induces both humoral and intestinal immunity. o Antibody is quickly produced in a large propoion of vacciness, even a single dose elicits substantial immunity. o The vaccine excretes the virus and so infects others who are also immunized thereby. o Useful in controlling epidemics. o Relatively inexpensive. Disadvantages o OPV is a thermolabile vaccine -p maintenance of cold chian is required and vaccine is stored at -20degC in deep freez. Also know o Stabilized vaccine Recent oral polio vaccines are heat stabilised. They can be kept without losing potency for a year at 4degC and for a month at room temprature.