Rationale: Vaccination of the older adults is often advised as they are a high-risk population; however, vaccine efficacy generally decreases with age. This is mainly due to a decrease in adaptive immune responses known as immunosenescence, which is a factor influencing the response to influenza vaccination. On the other hand, there are vaccines that show high efficacy (more than 95%) in older adults, one of the most effective being the AS01 adjuvanted herpes zoster vaccine, Shingrix. The differential immune pathways associated with vaccine responsiveness as well as the immune mechanisms by which adjuvants overcome immunosenescence remain poorly understood. Targeting key immune pathways could be a way to improve vaccine efficacy in older adults.~Objective: To explore immunological features between young and older adults after administration of an adjuvanted herpes zoster (Shingrix) or influenza unadjuvanted (Fluarix) vaccine that could explain differences in vaccine immunogenicity.~Study design: A single centre open label, randomised, and partially placebo-controlled trial Study population: Approximately 140 healthy adults, 80 of which are between 18-35 years old, the other 60 are 60+ years old.~Intervention: Two groups of young and elderly volunteers receive recombinant zoster vaccine (Shingrix), while two other groups will receive a quadrivalent influenza vaccine (Fluarix). Two groups of young volunteers will receive a placebo.~Main study parameter: To identify immune senescence-related differences contributing to vaccine immunogenicity
Vaccines are used to prevent infectious diseases worldwide. Unfortunately, many vaccines, like the flu vaccine, are less effective in older adults.~This single-centre open label partially randomised, partially placebo-controlled trial evaluates the differences in immune response between young and older adults after vaccination with a quadrivalent inactivated influenza vaccine and an adjuvanted herpes zoster vaccination.~Exploring the underlying mechanisms between the differences in immunogenicity can provide important information for future vaccine development.