New publication by UKER: Yellow Fever Vaccination: How Long-Lived Immune Memory Is Established

Researchers at FAU Erlangen-Nürnberg and Universitätsklinikum Erlangen show that an early metabolic "standby mode" — established in T cells shortly after vaccination — is the key to durable immune protection. The findings could reshape how we design and evaluate vaccines. 

The yellow fever vaccine (YF17D) is one of the most effective immunizations ever developed. A single dose can provide robust protection lasting decades — possibly a lifetime. Because of the extraordinary durability of the immune responses it generates, YF17D has over the past 15 years emerged as a uniquely powerful model system for studying human immune memory directly in vaccinated individuals. 

But how exactly do some T cells manage to persist for decades, while most others disappear within weeks of vaccination? A research team led by Prof. Dr. Kilian Schober, Heisenberg Professor of T-Cell Immunology at the Institute of Microbiology of Universitätsklinikum Erlangen (FAU Erlangen-Nürnberg), has now provided a strikingly clear answer — published in the journal Nature Immunology. 

The Study 

In the context of Yellow4FLAVI, the team examined more than 50 healthy adults immediately following yellow fever vaccination, tracking their immune responses over a full year. They also analysed blood samples from individuals vaccinated against yellow fever between 7 and 26 years earlier, enabling a direct comparison between T cells at the height of the acute immune response and those that had persisted silently for decades. 

To measure the metabolic activity of individual T cells, the researchers used puromycin — a substance that is incorporated into proteins during active cell metabolism. The more metabolically active a cell, the more puromycin it takes up, allowing the team to quantify metabolic flux at both the subset and single-cell level. 

🔬 Key Findings 

✅ Long-lived memory cells are metabolically quiet: Contrary to the intuition that durability requires sustained high activity, the T cells that persist longest after vaccination are among the least metabolically active. Long-term immune memory is built on restraint — not on consistent peak performance. 

✅ An early "standby mode" defines future memory: Already in the first weeks after vaccination, a subset of naive-like memory precursor cells enters a metabolically quiescent state, relying almost exclusively on oxidative phosphorylation — a more efficient and sustainable energy pathway. This early metabolic switch marks cells destined to become long-lived sentinels of the immune system. 

✅ A general principle, not a yellow fever-specific effect: The team validated their findings in two independent mouse models of bacterial and viral infection, and in individuals recently vaccinated against SARS-CoV-2. The same pattern emerged, demonstrating that metabolic quiescence is a fundamental principle of immunological memory — not a peculiarity of the yellow fever vaccine. 

✅ Implications for vaccine design and immunomonitoring: These findings suggest that vaccine immunogenicity studies may need to look beyond counting T cells or assessing surface markers — and start integrating metabolic readouts to better predict the durability of vaccine-induced protection. Understanding and promoting this early metabolic programming could guide the development of more targeted vaccines and immunotherapies. 

These results are directly relevant to the goals of the Yellow4FLAVI project, which uses the yellow fever vaccine as a benchmark platform to investigate protective immunity against flaviviruses — including dengue, Zika, and West Nile virus — and to translate those insights into the next generation of vaccines. 

📖 Read the publication here: https://doi.org/10.1038/s41590-026-02421-w 

Metabolic quiescence of naive-like memory T cells precedes and maintains antigen-specific T cell memory 

Frischholz, S., Schuster, EM., Grotz, M. et al. Metabolic quiescence of naive-like memory T cells precedes and maintains antigen-specific T cell memory. Nat Immunol 27, 452–462 (2026). https://doi.org/10.1038/s41590-026-02421-w   Nature Immunology — DOI: 10.1038/s41590-026-02421-w