Effect of weekly zinc supplements on incidence of pneumonia and diarrhoea in children younger than 2 years in an urban, low-income population in Bangladesh: randomised controlled trial

Background Pneumonia and diarrhoea cause much morbidity and mortality in children younger than 5 years. Most deaths occur during infancy and in developing countries. Daily regimens of zinc have been reported to prevent acute lower respiratory tract infection and diarrhoea, and to reduce child mortality. We aimed to examine whether giving zinc weekly could prevent clinical pneumonia and diarrhoea in children younger than 2 years. Methods 1665 poor, urban children aged 60 days to 12 months were randomly assigned zinc (70 mg) or placebo orally once weekly for 12 months. Children were assessed every week by field research assistants. Our primary outcomes were the rate of pneumonia and diarrhoea. The rates of other respiratory tract infections were the secondary outcomes. Growth, final serum copper, and final haemoglobin were also measured. Analysis was by intention to treat. Findings 34 children were excluded before random assignment to treatment group because they had tuberculosis. 809 children were assigned zinc, and 812 placebo. After treatment assignment, 103 children in the treatment group and 44 in the control group withdrew. There were significantly fewer incidents of pneumonia in the zinc group than the control group (199 vs 286; relative risk 0.83, 95% CI 0.73-0.95), and a small but significant effect on incidence of diarrhoea (1881 cases vs 2407; 0.94, 0.88-0.99). There were two deaths in the zinc group and 14 in the placebo group (p=0.013). There were no pneumonia-related deaths in the zinc group, but ten in the placebo group (p=0.013). The zinc group had a small gain in height, but not weight at 10 months compared with the placebo group. Serum copper and haemoglobin concentrations were not adversely affected after 10 months of zinc supplementation. Interpretation 70 mg of zinc weekly reduces pneumonia and mortality in young children. However, compliance with weekly intake might be problematic outside a research programme.