Acute respiratory infections particularly clinical pneumonia are one of the most common causes of death world-wide. Clinical pneumonia in children less than 5 years old in developing countries is approximately 0.29 episodes per child-year or about 151.8 million cases per year of which 8.7% require hospitalization. An additional 4 million children are hospitalized in developed countries per year.

There are great differences across the world with the distribution of pneumonia cases. The 5 countries with the highest incidence of clinical pneumonia are India, China, Pakistan, Bangladesh and Nigeria. Even within these countries there are differences, for example rural areas often have higher incidences. Estimates of pneumonia mortality in children less than 5 years of age is about 2 ...