In regions where anaemia prevalence still exceeds 40%, WHO recommends provision of daily multiple micronutrient sachets containing 10·0–12·5 mg elemental iron with a target of at least 90 doses per 6 months in children aged 6–23 months and 2–12 years; however, there are concerns that iron supplementation could increase the risk of infection.8, 15, 25 In this trial, we tested whether a hepcidin-guided screen-and-treat approach could reduce the iron dosage given, while maintaining a non-inferior efficacy. This evidence concerns the gene HAMP and anemia (phenotype).