Immunization in the adult immunocompromised host.

The number of patients with impaired immune response has been steadily increasing within the last years, not only with the onset of the AIDS epidemic, but also due to increasing numbers of subjects on immunosuppressive therapies. These patients are at an increased risk for infections, many of which are preventable by immunization. Inactivated vaccines are generally safe in subjects with underlying immunosuppression. However, immune response and protection may be hampered, depending on the extent of immunosuppression. In contrast, live vaccines such as yellow fever, measles, rubella, herpes zoster, and cholera may lead to severe reactions in immunocompromised patients and have been shown to deteriorate some immune-mediated diseases such as multiple sclerosis. Data on the efficacy of vaccines in biological therapies is scarce. Where necessary vaccines should be updated before immunosuppressive therapies are started. To improve the vaccination status several guidelines exist for immunosuppressed patients at risk such as those with rheumatic diseases, asplenia or solid organ and hematopoietic stem cell transplantation.