Influenza (flu) is a highly contagious viral infection that affects the respiratory system and can cause mild to severe symptoms. The flu is one of the most severe and common viral illnesses of the winter season. It is easily spread from person to person, usually when an infected person coughs or sneezes.
Pneumonia is a serious infection in one or both of your lungs that causes inflammation. The air sacs fill with pus and other liquid, blocking oxygen from reaching the bloodstream. If there is too little oxygen in the blood, the body's cells cannot work properly, which can lead to death.
Risk Factors
The flu is a common cause of pneumonia, especially among individuals at increased risk including:
- Young children
- Adults 65 and older, and
- Individuals with certain chronic health conditions like chronic lung, heart or liver disease, diabetes or weakened immune systems
Prevention Strategies
In addition to the flu, COVID-19, RSV and other respiratory viruses can lead to pneumonia particularly among individuals at increased risk. Keeping up to date on recommended immunizations is the best way to help protect yourself from severe respiratory illnesses. As flu strains change each year, it is necessary to get a flu vaccination each season to make sure you are protected against the most current strains.
Additional immunizations may be recommended to help prevent infections and severe illness caused by bacteria and viruses that may lead to pneumonia. Ask your healthcare provider about what immunizations are recommended for you and the people you care for.
Page last updated: June 3, 2025
