Can you slow down the ageing of your immune system?

The immune system begins to change early in life, not only at an advanced age. A large study of more than 300 healthy adults between the ages of 25 and 90 showed that T cells become differently programmed already at younger ages, and that memory T cells develop a shifted profile that cooperates less effectively with B cells. As a result, older people respond noticeably less well to vaccines, such as the seasonal flu vaccine. This pattern could not be explained solely by chronic inflammation or a previous herpesvirus infection; it appears to be an intrinsic part of ageing.

These changes have real consequences. Older people become more susceptible to serious infections, and their innate immune defences slow down: immune cells move less quickly to the site of an infection, kill pathogens less effectively, and produce inflammatory substances in a way that no longer responds optimally to danger. At the same time, a low-grade chronic inflammation smoulders throughout the body, a phenomenon researchers call 'inflammaging'. That subtle but persistent fire contributes to vulnerability to a wide range of conditions.

Adapting vaccinations to the ageing immune system demonstrably helps. Vaccines containing additional immune-stimulating substances (so-called adjuvants) have so far proved the most consistently effective in older people. High-antigen flu vaccines provide better protection than the standard version. mRNA vaccines also produce strong responses in older people, although these are smaller than in younger individuals.

One unexpected finding deserves separate attention: shingles vaccination appears to go beyond protection against shingles alone. A quasi-experiment in Australia, in which one group was just eligible and another just ineligible for the free vaccine, found that vaccinated individuals had an almost two percentage point lower chance of a new dementia diagnosis over more than seven years. This confirms an earlier study in Wales. Additional observational research found that vaccinated individuals also had lower inflammatory markers and aged biologically more slowly, although such a study cannot prove a cause-and-effect relationship. Whether the shingles vaccine genuinely slows biological ageing or whether other factors play a role has not yet been clarified.