<prompt> Threshold level of herd immunity for Peussis is80709050  <response>: 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. 