Pneumonia is a serious infection of the lungs caused by bacteria or viruses. The lungs fill up with fluid preventing oxygen from reaching the blood, thus causing the spread of infection throughout the body. In 2000, pneumonia and influenza combined ranked as the seventh leading cause of death. Because pneumonia is a common complication of influenza, getting a flu shot every year is good pneumonia prevention. A vaccine for pneumonia is also available. Early intervention with appropriate antibiotics can treat bacterial pneumonia. Supportive treatments, such as receiving supplemental oxygen, can increase the needed levels of oxygen in the body.