title: Epidemiological data needed in planning immunization programmes.
mesh_terms: D004165:Diphtheria / Q000276:immunology; D004812:Epidemiologic Methods; D006801:Humans; D007114:Immunization; D011051:Poliomyelitis / Q000276:immunology; D011159:Population Surveillance; D011635:Public Health Administration; D013742:Tetanus / Q000276:immunology