[Vaccine protection in the elderly: are Austrian seniors adequately protected by vaccinations?]. / Impfschutz im Alter: Sind österreichische Senioren durch Impfungen ausreichend geschützt?

OBJECTIVE: The aim of the study was to evaluate, if elderly persons are sufficiently protected against infectious diseases by vaccination. PROBANDS AND METHODS: 300 elderly (> 60 years) and 300 young (< 35 years) persons from five Austrian cities were recruited according to the criteria of a field study. Antibody concentrations against tetanus, diphtheria, tickborne encephalitis and influenza were assessed by ELISA or by haemagglutination inhibition test. Disease and vaccination histories were recorded. RESULTS: The results of the study demonstrate that protection against infectious diseases was frequently insufficient in the elderly. This was partly due to the fact that old persons were not vaccinated according to recommended strategies. However, low antibody concentration and a short duration of protective humoral immunity were also observed in many elderly persons in spite of regular vaccination. This was not only the case in frail, but also in healthy elderlies. CONCLUSION: The data demonstrate that vaccination has a relatively weak and short-lasting effect in old age. The results of the study should stimulate discussions about strategies how vaccinations can be made more effective in old age. Improved campaigns, shortened vaccination intervals as well as the design of novel vaccines tailored to fulfill the specific demands of the aging immune system are imaginable.

Insufficient protection for healthy elderly adults by tetanus and TBE vaccines.

Little information is available on post-vaccination antibody concentrations and the duration of protection in persons of more than 20 years of age. We, therefore, measured antibodies specific for tetanus (TT) or tick-borne encephalitis (TBE) virus in 734 adults (age 18-93 years, 382 females and 352 males) and evaluated these data in connection with the time point of the last vaccination against tetanus or TBE and age. This analysis revealed that the time of the last vaccination as well as age had highly significant effects on tetanus and TBE titers (p < 0.001). Our results show a strong decline in post-vaccination antibody concentrations with age, which sets in at the age of 40 in the case of tetanus, and is observed right throughout adult life in the case of TBE. Persons over 60 years of age frequently do not have protective antibody concentrations. We conclude that immunological responsiveness to vaccination decreases throughout adult life, and that conventional vaccination strategies designed for children and young adults cannot be uncritically applied in the elderly.

Lack of antibody production following immunization in old age: association with CD8(+)CD28(-) T cell clonal expansions and an imbalance in the production of Th1 and Th2 cytokines.

Although it is generally recognized that the function of the immune system declines with age, the nature of the underlying defects is still poorly understood. We now demonstrate the predominance of CD8(+)CD28(-) T cell clonal expansions in elderly persons who fail to produce specific Abs following influenza vaccination. These clones express effector cell markers and are mostly CD45RA(+). When isolated and put into culture, they are unable to proliferate, but produce IFN-gamma (but no IL-5) upon stimulation with anti-CD3 or autoantigen. These autoreactive CD8(+) type 1 effector cells seem to trigger a Th1 polarization, as CD4(+) T cells from elderly persons without in vivo Ab production produce Th1, but only low amounts of Th2 cytokines upon in vitro stimulation with PHA. Therefore, the increased occurrence of CD8(+)CD28(-) clonal expansions may be decisive for the development of immune deficiency in the elderly.