Threshold level of herd immunity for Peussis is

Ans. is 'c' i.e., 90% Advantage of herd immunity o It is not necessary to achieve 100% immunization to control a disease by providing herd immunity. o When a ceain percentage of population, is vaccinated, the spread of disease is effectively stopped. o This critical percentage is referred to as herd immunity threshold. Disease Herd immunity threshod Diphtheria 85% Measles 83-94% Mumps 75-86% Peussis 92-94% Polio 80-86% Rubella 80-85% Small pox 83-85% Limitation of Herd immunity o Only a small fraction of the population (or herd) can be left un-vaccinated for this method to be effective.