Strengthening memory immunity in the aged population by vaccinating pre-elderly

The world population is ageing. In 2060 about 30% of the population is predicted to be above 65 years, compared to 17.4% in 2010. Ageing of the world population forms one of the major challenges of the 21st century. Population ageing has implications for the medical conditions, as with age the vulnerability for chronic diseases and severe infections increases. Prevention of infectious diseases by timely immunization of the elderly population is a prerequisite to
establish healthy ageing.Due to the demographic changes in the future population, vaccination programmes need to shift to a life-course scheme. Childhood vaccinations remain extremely important to induce immunity, but it is also necessary to maintain immunity afterwards, before reaching old age. Immunization of elderly is challenging, due to changes in the immune system with age, which cause difficulties to respond to vaccination (immunesenescence). It has been suggested that immunization against antigens has to be established before the onset of immunesenescence, most probably in the 5th or 6th decade of life. Using this strategy, the protection of elderly against infectious diseases might be improved. Biomarkers that predict
vaccination responses earlier in life might also help to protect the aged population, since precautions can be taken before the onset of immunesenescence when low response to the vaccination is expected.

The main objective of this study is to determine remarkable differences in vaccine responses in the pre-elderly age group (50-65 years of age) to a primary immunization with vaccine antigens to which no or (very) low pre-vaccination antibody levels and memory cells exist.

The MenACWY-TT (against Meningococcal ACWY) and VZV (against Varicella Zoster)
vaccines will be used to study these differences.
Moreover, the utility of biomarkers that predict the responsiveness of pre-elderly persons will be explored.

The main objective of this study is to determine remarkable differences in vaccine responsesin the pre-elderly age group (50-65 years of age) to a primary immunization with vaccine antigens to which no or (very) low pre-vaccination antibody levels and memory cells exist.

The MenACWY-TT (against Meningococcal ACWY) and VZV (against Varicella Zoster)
vaccines will be used to study these differences. Moreover, the utility of biomarkers that predict the responsiveness of pre-elderly persons will be explored.

MenACWY: before vaccination (T0), post-vaccination: 7 days (T1), 28 days (T2), and 1 year (T3)

VZV: before vaccination (T0), post-vaccination: 14 days (T1), 28 days (T2), and 1 year (T3)

Two different study populations will be recruited, one group will be administered the MenACWY-TT vaccine and the other group the VZV vaccine. For the MenACWY-TT study group 200 persons will be included. Blood samples will be drawn pre-vaccination (T=0). Post-vaccination blood
samples will be drawn at 7 days (T=1), 28 days (T=2) and 1 year (T=3).

In the VZV study group 50 persons will be included, since it is considered a pilot study. Blood samples will be drawn pre-vaccination (T=0).
Postvaccination
blood samples will be drawn after 14 days (T=1), 28 days (T=2), and 1 year
(T=3). Moreover, participants of both study groups will be asked whether we are allowed to contact them again, for example for an extra blood sampling after 5 years. At T=0 and T=3 participants will be asked to fill in a general health questionnaire.