Herd immunity to pertussis.
D002675:Child, Preschool; D004196:Disease Outbreaks / Q000453:epidemiology*; D006801:Humans; D010567:Pertussis Vaccine / Q000276:immunology*; D013997:Time Factors; D014611:Vaccination; D014900:West Indies; D014917:Whooping Cough / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control
D010567:Pertussis Vaccine