Second-hand smoke exposure linked to TB infection or disease in children/adolescents: systematic review and meta-analysis

BACKGROUND TB, including Mycobacterium tuberculosis ( Mtb ) infection and TB disease, is a leading cause of morbidity and mortality among children and adolescents aged 0–18 years in low-resource settings. Second-hand smoke (SHS) exposure is a widespread public health threat, and children are especially vulnerable due to their developing immune and respiratory systems. However, evidence regarding the association between SHS exposure and childhood TB risk remains inconsistent across observational studies. METHODS This PROSPERO-registered meta-analysis (CRD420261354572) searched seven databases and grey literature from 2000 to December 2025. We included English observational studies of 0–18-year-old children/adolescents in low-resource settings. Study quality was assessed via the Newcastle–Ottawa Scale, and pooled odds ratios (ORs) were calculated. RESULTS Twelve eligible studies with a total of 6,411 participants were pooled for analysis. Compared with children and adolescents without household SHS exposure, those exposed to SHS had significantly elevated combined odds of Mtb infection or TB disease. The pooled OR was 2.689 (95% confidence interval: 2.384, P < 0.001), with negligible between-study heterogeneity (I 2 = 0.0%). Egger’s test suggested mild publication bias across included studies. CONCLUSION SHS exposure is significantly associated with higher pooled odds of Mtb infection or TB disease among children and adolescents in low-resource settings.