Epidemiologic detention of agents whose effects depend on host susceptibility.
D002675:Child, Preschool; D006801:Humans; D007109:Immunity; D007223:Infant; D007231:Infant, Newborn; D007938:Leukemia; D008457:Measles; D008962:Models, Theoretical; D011446:Prospective Studies; D012189:Retrospective Studies