The median MBL concentration for all patients was 918 ng/mL (interquartile range 508-1683 ng/mL, inclusive range 0-8194 ng/mL). The median MBL concentration in subjects randomized to receive azithromycin or placebo was 1008 ng/mL (95% confidence interval [CI] 909-1082) and 850 ng/mL (95% CI 776-929), respectively (P = 0.017).