Children and adolescents immunized according to the recommended childhood and adolescent immunization schedule (see Fig 1.1-1.3) should be considered to be protected against diseases for which they were immunized. Disease-specific chapters should be consulted for details.

Measles and varicella vaccines have been demonstrated to provide protection in some susceptible people if administered within 72 hours after exposure. Measles or varicella immunization should be recommended immediately for all nonimmune people during a measles or varicella outbreak, respectively, except for people with a contraindication to immunization. Students immunized for measles or varicella for the first time under these circumstances should be allowed to return to school after immunization. Susceptible children and adolescents 12 months of age or older exposed to HAV should receive single-antigen hepatitis A vaccine (or Immune Globulin) within 14 days after exposure. People who are immunocompromised, are older than 40 years of age, or have liver disease should receive Immune Globulin (see Hepatitis A).¹

Mumps vaccine given after exposure has not been demonstrated to prevent infection among susceptible contacts, but immunization should be administered to unimmunized students to protect them from infection from subsequent exposure.