herd immunity: Quick Facts

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Facts

Also Known As	community immunity

Photos

Three line graphs display the dramatic decline in reported cases of diphtheria, polio, and measles in the United States from 1920 to 2019, each showing a sharp drop after the introduction of their respective vaccines. Diphtheria cases fell after 1921, polio after 1955, and measles after 1963, illustrating the impact of mass vaccination programs. An inset highlights an increase in measles cases after 2010.

A nurse administers a vaccine to a young girl in a crowded clinic, while other women and children wait in line behind her in Nagaon, Assam, India.

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Topics

specific immunity immunization