Background: Pneumonia is the leading cause of childhood mortality, accounting for 19% of the 10.6 million deaths that occur each year1. Case-control studies from Ethiopia2 and India3 suggest that sub-clinical vitamin D deficiency may increase ten times the risk of pneumonia in children. We postulate that controlling childhood vitamin D deficiency has the potential to dramatically reduce the incidence of pneumonia and save >700,000 lives each year since vitamin D deficiency is widespread in developing countries.

Aim: To investigate whether 3-monthly oral supplementation of 100,000iu vitamin D reduces pneumonia and its consequences among children aged 1-12 months (followed for 18 months), living in a deprived area of Kabul, Afghanistan, where >70% of young children are vitamin D deficient (<8ng/dl). The effect of vitamin D on the incidence of other diseases, in particular diarrhea and rickets will also be investigated.

Methods: Randomised double-blind placebo-controlled trial: 3000 children will be randomised to receive either 6 doses of vitamin D or placebo. The first dose will be given at the start of autumn and the second and subsequent doses every 3 months thereafter; children will be followed for 18 months. Incidence of pneumonia will be ascertained though weekly home visits (active surveillance) and from attendances and admissions at the trial clinic and wards in the hospital serving the study area (passive surveillance).