Effect on the incidence of pneumonia of vitamin D supplementation by quarterly bolus dose to infants in Kabul: a randomised controlled superiority trial

Randomized controlled superiority trial in inner-city Kabul, Afghanistan, among infants aged 1 to 11 months. The active vitamin D group included 1,524 participants, enrolled at Maiwand Teaching Hospital and followed for 18 months.

Infants in the active arm received oral vitamin D3 (cholecalciferol) 100,000 IU per dose in 0.5 mL olive oil every 3 months for 18 months. The preparation was administered by fieldworkers as a bolus regimen; the comparator was placebo in olive oil.

Vitamin D3 supplementation did not reduce radiographically confirmed pneumonia in this high-risk infant population. The incidence rate of first or only pneumonia episode was 0.145 per child per year in the vitamin D group versus 0.137 in the placebo group, with an incidence rate ratio of 1.06 (95% CI 0.89-1.27). Repeat all-type pneumonia was significantly higher in the vitamin D group, and hospital admissions and all-cause mortality were not improved. No immediate or other adverse events associated with vitamin D3 were recorded.

The trial was conducted in a single urban setting in Kabul, which may limit generalizability to other populations and seasons. Follow-up data were incomplete for some participants, and the main benefit sought was not observed despite improved vitamin D status, leaving limited evidence of clinical efficacy for this indication.