This study is limited by its cross-sectional nature and its small
sample size, as reflected in wide confidence intervals around
effect estimates despite statistically significant results for main
outcomes. Other limitations include the age distribution and
lack of serial measures to assess discordant results and test
reproducibility. Since this was a household contact study, we
did not assess individuals without documented M tuberculosis
exposure; future studies should incorporate the use of such
control populations and should ideally include serial measurements
of both exposure and infection. We do not report on
findings in HIV-infected patients. ELISPOT-based IGRAs have
been shown to be sensitive measures of M tuberculosis infection
in HIV-infected individuals in endemic settings and also in those
with decreased CD4+ T cell counts.