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Pneumonia is an infection of the lungs that can cause mild to severe illness in people of all ages. It is the leading cause of death in children younger than 5 years of age worldwide. However, these infections can often be prevented with vaccines and can usually be treated with antibiotics, antiviral drugs (such as Tamiflu), or specific drug therapies. Common signs of pneumonia include cough, fever, and difficulty breathing. You are more likely to become ill with pneumonia if you smoke or have underlying medical conditions, such as diabetes or heart disease. However, you can lower your chances by taking good care of your medical problems, and quitting smoking. You can also help prevent pneumonia and other respiratory infections by following good hygiene practices, such as washing your hands regularly and disinfecting frequently touched surfaces.

Common Causes of Pneumonia

Pneumonia can be caused by viruses, bacteria, and fungi. In the United States, common causes of viral pneumonia are influenza and respiratory syncytial virus (RSV), and a common cause of bacterial pneumonia is Streptococcus pneumoniae (pneumococcus). Pneumonia can also be caused as a result of being on a ventilator. This is known as ventilator-associated pneumonia.

Learn more below about the infections that commonly cause pneumonia.

Less Common Causes of Pneumonia

Vaccines Can Help Prevent Pneumonia

In the United States, there are several vaccines that prevent infection by bacteria or viruses that may cause pneumonia. These vaccines include

  • pneumococcal,
  • Haemophilus influenzae type b (Hib),
  • pertussis (whooping cough),
  • varicella (chickenpox),
  • measles, and
  • influenza (flu).


Etiology of Pneumonia in the Community (EPIC) Study

The Etiology of Pneumonia in the Community (EPIC) study conducted by CDC and three U.S. children’s hospitals and five U.S. adult medical centers estimated the burden of community-acquired pneumonia hospitalizations among U.S. children and adults from January 2010 – June 2012.