“Back then, I wasn’t ill so often”: With advancing age not only the skin loses its elasticity – many organs lose their functions. So does the immune system: Defense cells do not react promptly anymore, and immunological memory is not established. As a result, we are poorly protected by vaccines and more susceptible to infections. While the mechanisms of immune aging remain unknown, it is speculated that chronic viral infections play a crucial role in this age-related loss of immune functions. Read more about how pathogens may have an impact on the real age of our immune system.