title: A randomized trial of two coverage targets for mass treatment with azithromycin for trachoma.
abstract: BACKGROUND
  The World Health Organization recommends at least 3 annual antibiotic mass drug administrations (MDA) where the prevalence of trachoma is > 10% in children ages 1-9 years, with coverage at least at 80%. However, the additional value of higher coverage targeted at children with multiple rounds is unknown.
  
  
  METHODS
  2 × 2 factorial community randomized, double blind, trial.
  32 communities with prevalence of trachoma ≥ 20% were randomized to: annual MDA aiming for coverage of children between 80%-90% (usual target) versus aiming for coverag e> 90% (enhanced target); and to: MDA for three years versus a rule of cessation of MDA early if the estimated prevalence of ocular C. trachomatis infection was less than 5%. The primary outcome was the community prevalence of infection with C. trachomatis at 36 months.
  
  
  RESULTS
  Over the trial's course, no community met the MDA cessation rule, so all communities had the full 3 rounds of MDA. At 36 months, there was no significant difference in the prevalence of infection, 4.0 versus 5.4 (mean adjusted difference  = 1.4%, 95% CI  =  -1.0% to 3.8%), nor in the prevalence of trachoma, 6.1 versus 9.0 (mean adjusted difference  =  2.6%, 95% CI  =  -0.3% to 5.3%) comparing the usual target to the enhanced target group. There was no difference if analyzed using coverage as a continuous variable.
  
  
  CONCLUSIONS
  In communities that had pre-treatment prevalence of follicular trachoma of 20% or greater, there is no evidence that MDA can be stopped before 3 annual rounds, even with high coverage. Increasing coverage in children above 90% does not appear to confer additional benefit.
authors.affiliation: Dana Center for Preventive Ophthalmology, Johns Hopkins University, Baltimore, Maryland, USA. shwest@jhmi.edu
authors.forename: Sheila K
authors.initials: SK
authors.lastname: West
authors.forename: Robin
authors.initials: R
authors.lastname: Bailey
authors.forename: Beatriz
authors.initials: B
authors.lastname: Munoz
authors.forename: Tansy
authors.initials: T
authors.lastname: Edwards
authors.forename: Harran
authors.initials: H
authors.lastname: Mkocha
authors.forename: Charlotte
authors.initials: C
authors.lastname: Gaydos
authors.forename: Thomas
authors.initials: T
authors.lastname: Lietman
authors.forename: Travis
authors.initials: T
authors.lastname: Porco
authors.forename: David
authors.initials: D
authors.lastname: Mabey
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Quinn
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D017963:Azithromycin / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015995:Prevalence; D014141:Trachoma / Q000188:drug therapy* / Q000453:epidemiology* / Q000517:prevention & control; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents; D017963:Azithromycin