Shingles and RSV Vaccines Linked to Lower Dementia Risk in Older Adults: Study

AS01 is composed of monophosphoryl lipid A (MPL) and QS-21, substances that stimulate specific immune pathways. Prior research in animal models suggests that MPL may mitigate Alzheimer's-related changes in the brain, and both MPL and QS-21 activate immune cells and boost the production of interferon-gamma, a molecule linked to slower cognitive decline.

Although the exact biological mechanism remains uncertain, the researchers noted that the protective effect seems unlikely to be solely due to infection prevention since the observed benefits emerged within months of vaccination, too soon for infection avoidance alone to account for the dementia risk reduction.

The findings are based on retrospective observational data, and while the study adjusted for various confounding factors, the authors acknowledged limitations such as potential misclassification of vaccine brands and lack of socioeconomic data. Nevertheless, the consistent patterns across different analyses support the need for further exploration.

“Our data suggest that vaccines containing the AS01 adjuvant might offer benefits beyond infection prevention,” the authors stated. “Further clinical trials and mechanistic research are essential to confirm these effects and understand how long the protection might last.”

They conclude, "If confirmed, these findings could shape future strategies to delay or prevent dementia—one of the world’s leading causes of disability in older adults—using existing vaccination platforms."

Reference:

Taquet, M., Todd, J. A., & Harrison, P. J. (2025). Lower risk of dementia with AS01-adjuvanted vaccination against shingles and respiratory syncytial virus infections. Npj Vaccines, 10(1), 1-6. https://doi.org/10.1038/s41541-025-01172-3