The timely facilitation of immunologic (immunoglobulin or vaccine) or
antimicrobial prophylaxis is used in individuals who ha ve been expose
d to certain infectious diseases. Such methodology has been shown to b
e helpful in infections such as viral hepatitis types A and B, measles
, varicella, rabies, and tuberculosis. The data supporting such use in
rubella and mumps are not strong and information is still needed in h
epatitis C, human immunodeficiency virus, and Lyme borreliosis. This a
rticle reviews postexposure prophylaxis in these situations. Preventiv
e strategies for meningococcal disease, group A streptococcus, tetanus
, diphtheria, and pertussis are discussed elsewhere in this issue.