Pneumonia is the single most common cause of death in under-fives, accounting for a fifth of childhood deaths worldwide.
But if childhood vaccination programmes manage to halve mortality from severe pneumonia, strategies to combat the remaining disease will require a complete re-think.
Writing in PLoS Medicine, J. Anthony G. Scott and Mike English say current strategies focus on two vaccine preventable pathogens — Haemophilus influenzae type b (Hib) and pneumococcus.
If the 50 per cent mortality reduction is achieved, the present classification of pneumonia would be obsolete, they say. The many other causes of pneumonia, such as the bacteria Staphylococcus aureus, will need to be given more attention and vaccination campaigns may prove impractical or too expensive.
Distinguishing between pneumonia and asthma — on the rise in developing countries — will be important, as will consideration of the effect of tuberculosis and other risk factors, such as HIV infection, indoor air pollution and poor nutrition.
Better diagnostic tests will be required, as well as clinical trials at multiple sites to evaluate new treatments for the various causes of pneumonia.
The authors say this represents "at least a decade's work, yet the situation we anticipate will arrive in many developing countries before a decade is out."