How the flu turns deadly

Although most people do not die from the flu, young children and people with other illnesses, such as heart disease, lung disease and diabetes are at elevated risk.

Adults can succumb to the flu in three ways: pneumonia, sepsis and heart attack.

Pneumonia can develop in a person who is infected with influenza. Pneumonia causes the small air sacs of the lungs to fill with fluid or pus, sometimes leading to death.

With sepsis, the influenza virus can trigger the body to release chemicals into the blood to fight infection that triggers inflammation throughout the body. That inflammation can then trigger multiple organ system failure.

The third way the flu kills adults is by triggering heart attacks.