The investigators will conduct a n=5,400 Phase 3, double-blind, individually randomised
placebo-controlled clinical trial of 5 years' duration in primary schools in City of Cape
Town Metropolitan Municipality, Western Cape Province, Republic of South Africa.
The primary objective of the trial is to determine whether a weekly oral dose of 0.25 mg
(10,000 IU) vitamin D3, administered for three years, reduces risk of acquisition of latent
tuberculosis infection (LTBI) in Cape Town primary schoolchildren.
Statistical analysis will be performed on an intention-to-treat basis to compare acquisition
of LTBI in intervention vs. control arms during three-year follow-up. The primary analysis
will be logistic regression with presence/absence of LTBI at follow-up as the outcome,
adjusted for a random effect of school of attendance.