Long-Term Immune Response

The immune response of live-attenuated vaccines may last for decades; however, other types of antigens like inactivated and recombinant protein require booster immunizations.

QS-21 and other saponin-based adjuvants elicit predominantly Th1 immune responses, characterized by robust cell-mediated immunity while maintaining high level of antibody response. This immunological environment promotes immune memory, marked by the generation of polyfunctional CD4⁺ T cells and long-lived plasma cells in secondary response [1]. Evidence demonstrates durable immune responses lasting from one to nine years, and potentially longer [2, 3]. Although saponin-adjuvanted vaccines were first licensed for human use in the late 2010s—limiting the availability of long-term immunogenicity data—the immune memory induced by the herpes zoster vaccine is projected to persist for up to 15 years.

References

1.Wen, X. et al., 2025. Longitudinal single cell profiling of epitope specific memory CD4+ T cell responses to recombinant zoster vaccine. Nature Communications, Volume 16.

2.Chlibek, R. et al., 2016. Long-term immunogenicity and safety of an investigational herpes zoster subunit vaccine in older adults. Vaccine, 34(6), pp. 863-868.

3.Schwarz, T. F. et al., 2018. Persistence of immune response to an adjuvanted varicella-zoster virus subunit vaccine for up to year nine in older adults. Human Vaccines & Immunotherapeutics, 14(6).