This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
[{'content': 'Herd immunity is not important in: \nSelect and explain. \nA. Tetanus, B. Pertussis, C. Diphtheria, D. All', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The epidemics wave declines with a 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 disease. E.g. small pox eradication.\nIn the case of tetanus it does not protect the individual.\nEpidemiology of Infectious\nDiseases', 'role': 'assistant'}]