New research is shedding light on the immune system's role in “long COVID” — symptoms that linger past the typical course of COVID-19 — pointing the way to interventions that might treat this poorly understood condition.

Here are three key findings from recent studies:

• Those who suffered from severe COVID-19 have an immune system that shows changes commonly found naturally with biological aging three months after discharge from the hospital. However, it is not clear if these aging-related changes to the immune system were already present, or was a result of the COVID-19 infection.
• After severe COVID-19, approximately one third of patients have elevated and dysfunctional neutrophils, the white blood cells that protect us from infection. Elevated levels of neutrophils might promote excessive blood clotting. A person may have higher levels because of an infection.
• COVID-19 affects gene expression in proportion to its severity and duration, and severe cases can cause shifts in genetic expression that produce metabolic dysfunction and persistent immune changes.

While more research is needed, previous studies have shown that diet, exercise, and other interventions can reverse the changes associated with immune system aging. If such changes are a major factor in long COVID, the hope is that these healthy-living activities might help in recovery from long COVID too.