Smallpox vaccinations.
D000293:Adolescent; D000367:Age Factors; D002675:Child, Preschool; D005060:Europe; D006801:Humans; D007223:Infant; D007883:Legislation, Medical; D012899:Smallpox / Q000453:epidemiology / Q000517:prevention & control*; D014195:Travel; D014481:United States; D014611:Vaccination / Q000009:adverse effects