Does Treating Older Siblings Enhance the Impact of Azithromycin on Infant Survival? Insights from a Cluster-Randomized Trial in Niger

Highlights

• Mass drug administration (MDA) of azithromycin to children aged 1–59 months reduced infant (1–11 months) mortality by 23% compared to placebo.
• Adding azithromycin treatment for older siblings (12–59 months) provided an incremental mortality reduction among infants beyond direct treatment alone.
• Spillover benefits from treating siblings accounted for roughly three-quarters of the observed mortality reduction.
• Although the interaction between sibling treatment and infant mortality was not statistically significant, there was a trend toward lower mortality in infants living with treated older siblings.

Study Background and Disease Burden