Vaccine response in aging

The vaccine response deteriorates with aging due to multiple converging immunological deficits: reduced naive T- and B-cell diversity, impaired germinal centre reactions, diminished plasma cell longevity, and dysregulated innate sensing all lower the magnitude, affinity, and durability of vaccine-induced immunity. These deficits necessitate formulation adaptations in vaccines targeted at older adults — high-dose or adjuvanted influenza vaccines (e.g., Fluzone High-Dose, Fluad with MF59 adjuvant) elicit substantially stronger seroprotection rates than standard formulations in persons over 65. The recombinant subunit zoster vaccine Shingrix, which uses the AS01B adjuvant system to drive a strong CD4+ T-cell and antibody response, demonstrates approximately 90–97% efficacy against herpes zoster depending on age group (approximately 90% in adults aged 70+) compared with roughly 50% for the earlier live-attenuated Zostavax, which was discontinued in the US in 2020, illustrating how adjuvant engineering can partly compensate for age-related immunosenescence.