Pneumonia can affect anyone. But the two age groups at highest risk are: Children who are 2 years old or younger and people who are age 65 or older.
Other risk factors include:
Being hospitalized. You are at greater risk of pneumonia if you're in a hospital intensive care unit, especially if you're on a machine that helps you breathe.
Chronic disease. You're more likely to get pneumonia if you have asthma, chronic obstructive pulmonary disease (COPD) or heart disease.
Smoking. Smoking damages your body's natural defenses against the bacteria and viruses that cause pneumonia.
Weakened or suppressed immune system. People who have HIV/AIDS, who've had an organ transplant, or who receive chemotherapy or long-term steroids are at risk.