Pneumonia can affect people of all ages. However, two age groups are at greater risk of developing pneumonia:
Infants who are 2 years old or younger (because their immune systems are still developing during the first few years of life);
People who are 65 years old or older;
Other conditions and factors also raise your risk for pneumonia. You're more likely to get pneumonia if you have a lung disease or other serious disease. Examples include cystic fibrosis, asthma, COPD (chronic obstructive pulmonary disease), bronchiectasis, diabetes, heart failure, and sickle cell anemia.
You're at greater risk for pneumonia if you're in a hospital intensive-care unit, especially if you're on a ventilator (a machine that helps you breathe).
Having a weak or suppressed immune system also raises your risk for pneumonia. A weak immune system may be the result of a disease such as HIV/AIDS. A suppressed immune system may be due to an organ transplant or blood and marrow stem cell transplant, chemotherapy (a treatment for cancer), or long-term steroid use.
Your risk for pneumonia also increases if you have trouble coughing because of a stroke or problems swallowing. You're also at higher risk if you can't move around much or are sedated (given medicine to make you relaxed or sleepy).
Smoking cigarettes, abusing alcohol, or being undernourished also raises your risk for pneumonia. Your risk also goes up if you've recently had a cold or the flu, or if you're exposed to certain chemicals, pollutants, or toxic fumes.