Brazilian version of the Vaccine Trust Gauge for adolescents

Aim To cross-culturally adapt the Vaccine Trust Gauge (VTG) for the Brazilian context and evaluate its content validity, structural validity, internal consistency, and test–retest reliability among adolescents. Methods This methodological study involved the cross-cultural adaptation of the VTG and the evaluation of its content validity, structural validity, internal consistency, and test–retest reliability. Content validity was assessed by an expert committee. Pre-testing was conducted with adolescents to evaluate clarity and acceptability. Internal structure was examined using confirmatory factor analysis (CFA) with the weighted least squares mean and variance adjusted estimator for ordinal data. Reliability was assessed using McDonald's omega and test–retest analysis with the intraclass correlation coefficient (ICC). Results The Brazilian version demonstrated strong content validity (Content Validity Index = 0.90). Pre-testing indicated good comprehension following minor linguistic adjustments. CFA supported the three-factor model (trust, importance, recommendation), with excellent fit indices (CFI = 0.972; TLI = 0.962; RMSEA = 0.056; SRMR = 0.052). Internal consistency ranged from 0.70 to 0.89. Test–retest analysis showed moderate temporal stability (ICC = 0.74). Conclusion The Brazilian VTG provides initial evidence of validity and reliability for assessing vaccine trust among adolescents. The instrument may support monitoring of vaccine trust, inform targeted interventions, and guide public health strategies across diverse immunization contexts.