The trial, Macrolides Oraux pour Réduire les Décès avec un Oeil sur la Résistance (MORDOR) (NCT02047981) demonstrated that biannual distribution of azithromycin to children 1-59 months old reduces child mortality. Targeting treatment to children 1-11 months old could reduce selection for resistance by limiting antibiotic distributions while maximizing the mortality benefit by targeting treatment to children at the highest mortality risk. Such a targeted intervention remains untested, however. The investigator's objective in this study is to determine the optimal age group to treat with biannual oral azithromycin distribution to reduce child mortality.

Eligible communities in Niger will be randomized to one of three azithromycin distribution strategies: 

1) biannual oral azithromycin to children 1-11 months old with biannual oral placebo to children 12-59 months old, 

2) biannual oral azithromycin to children 1-59 months old, or 

3) biannual oral placebo to children 1-59 months old.

Mortality will be monitored through biannual census data collection, which will be used to adaptively allocate treatment assignments, with the allocation updated at each treatment period and individual communities retaining their allocation for 4 distributions. Antimicrobial resistance will be monitored using cluster sampling of different groups of children and adults in the Dosso region. Additional data will be collected on implementation outcomes, including costs, reach and coverage, acceptability/adoption, and maintenance/sustainability.

Implementation will be phased in by region. Dosso will be enrolled in the first year, Maradi and Zinder in the second year, and secure areas of Tillabéri and Tahoua and in the third year.