Pre-trial treatments: in the original MORDOR trial, communities were randomized to 4 rounds of biannual mass distributions of either azithromycin or placebo (i.e, the first two years of the trial). All communities were subsequently treated with 2 rounds of biannual mass azithromycin (i.e., the fifth and sixth rounds, during the third year of the trial).~Present trial design: The present trial enrolls all communities previously enrolled in the Niger site of MORDOR, and re-randomizes communities to biannual mass distributions of either azithromycin or placebo (i.e., the seventh, eighth, ninth and tenth rounds of mass drug administration since randomization for the original MORDOR trial, occurring in the fourth and fifth year since randomization). This results in four patterns of community-based treatment: four years of azithromycin (AAAAA), three years of azithromycin followed by one year of placebo (AAAPP), two years of placebo followed by two years of azithromycin (PPAAA), and two years of placebo followed by one year of azithromycin and then one year of placebo (PPAPP). The primary outcome will be all-cause mortality in children aged 1-59 months,as determined by biannual census. The mortality rate following re-randomization (i.e., the seventh, eighth, ninth and tenth rounds of mass drug administration) will be compared between the two re-randomized groups.
MORDOR was a cluster-randomized placebo controlled trial that assessed the efficacy of mass azithromycin distributions for the prevention of childhood mortality. All communities were subsequently treated with mass azithromycin for one year. The present trial re-randomized communities to azithromycin or placebo for the fourth and fifth year of the study.