Risk factorsBy Mayo Clinic staff
Pneumonia can affect anyone. But the two age groups at highest risk are:
- Infants and children younger than age 2 years, because their immune systems are still developing
- People older than age 65
Other risk factors include:
- Certain chronic diseases, such as asthma, chronic obstructive pulmonary disease and heart disease
- Weakened or suppressed immune system, due to factors such as HIV/AIDS, organ transplant, chemotherapy for cancer or long-term steroid use
- Smoking, which damages your body's natural defenses against the bacteria and viruses that cause pneumonia
- Being placed on a ventilator while hospitalized
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