ABSTRACT
VACCINE EFFICACY IN THE ELDERLY The implementation of large-scale vaccination strategies led to the eradication of smallpox in 1980 and to a drastic reduction of poliomyelitis, diphtheria, tetanus, pertussis, measles, mumps, rubella, and Haemophilus influenzae infections. More than 25 different infectious diseases can be prevented by vaccinations these days and vaccinations are considered the most cost-effective medical procedure for preventing morbidity and mortality caused by infectious diseases. However, the problem of decreased vaccine efficacy in the elderly, due to an age-related decline in immune system functions, has been recognized only recently. Especially the induction of protective antibody levels as well as functional and long-lived memory T-cell numbers in the case of vaccinations with new antigens remain a major problem in old age (Fig. 2). The situation of elderly persons is further aggravated by a different clinical presentation of infectious diseases, the failure to respond sufficiently to therapy, the frequent occurrence of opportunistic or recurrent infections and the reactivation of latent diseases, for instance those caused by varicella-zoster virus (VZV) and Mycobacterium tuberculosis.
