Intervention and randomization.
Participants were randomized in a 1:1 fashion to a single oral 20-mg/kg dose of azithromycin or matching placebo (both provided by Pfizer, Inc, New York, NY) after enrollment and baseline assessments. Dosing was based on a weight measurement on a standard infant scale (ADE M112600 U Scale) and the study’s electronic data capture application automatically calculated the volume of a 20 mg/kg dose of azithromycin or equivalent volume of placebo. Study treatment was delivered by syringe, and all study treatments were directly observed and recorded in the study’s data capture application. The randomization sequence was generated by the trial’s unmasked data team without blocking or stratification using R (The R Foundation for Statistical Computing, Vienna, Austria).