We know the immune system is the key to fighting illness, but what we are learning is that it is also important for helping us live longer, regardless of the threat it might be fighting.

Immune resilience is the term for the ability of the immune system to rapidly launch attacks that defend against infectious invaders such as viruses. But it includes how well the body responds to aging or other health conditions while keeping potentially damaging inflammation under wraps.

To look at the role of immune resilience, an international team of researchers examined multiple studies on immune response using two patterns: one that looked at the immune response according to a pattern of survival, and the other associated with death.

Among their findings, the researchers discovered that while immune resilience generally declines with age, some people maintain higher levels for reasons that aren’t yet known. Some people also maintain higher levels of immune resilience despite the presence of inflammatory stress such as HIV infection or acute COVID-19 disease.

While people of all ages can show high or low immune resilience, the study found that higher levels are more common in females than males.

The findings suggest that there’s a lot more to learn about why people differ in their ability to fight off infections and chronic illness. With further research, it may be possible to develop methods to encourage or restore immune resilience as a way of improving general health.