What Causes Pneumonia?
Pneumonia is usually caused by bacteria and viruses. The most common cause of bacterial pneumonia is Streptococcus pneumoniae. Viral infections such as influenza could directly lead to pneumonia (primary viral pneumonia) or increase the risk of secondary bacterial pneumonia.
What Causes Pneumonia
Professor Brian Duerden, CBE, explains how pneumococcal disease can cause pneumonia and other invasive infections. He describes the effects of the disease on older people and children, and what you can do to prevent it.