Herd immunity is not impoant in
High-Yield Explanation
The epidemics wave declines with an up-built of herd immunity after natural infection and if high-level immunity maintained with immunization disease eliminated, e.g. Polio, Diphtheria. It is neither possible nor necessary to achieve 100% herd immunity in a population to halt an epidemic or to control the disease. E.g. smallpox eradication. In the case of tetanus, it does not protect the individual. Epidemiology of Infectious Diseases. Ref: Park text book 24th edition.