Psychometric validation of the 5-item parent attitudes about childhood vaccines survey (PACV-5) in an Italian parental population

: To evaluate the psychometric properties of the Italian version of the Parent Attitudes about Childhood Vaccines Survey (PACV-5), a total of 308 parents/legal guardians of children aged 0-18 years completed an anonymous online survey (EUSurvey®). Structural validity was assessed using confirmatory factor analysis (CFA). Convergent validity was assessed by correlating PACV-5 scores with health literacy and vaccine confidence measures. Measurement invariance across education levels was tested using the multiple indicators multiple causes (MIMIC) approach. Reliability was evaluated with Cronbach's α and Omega coefficient (ω). Precision was assessed through the standard error of measurement (SEM) and smallest detectable change (SDC). The PACV-5 total score (M = 2.00, SD = 2.36) reflected low vaccine hesitancy. CFA supported a unidimensional structure with good fit indices (RMSEA = 0.057, CFI = 0.99). Convergent validity was confirmed by significant negative correlations between PACV-5 and health literacy (r =  - 0.32 and r =  - 0.25, p < 0.001, respectively), the Vaccine Confidence Index (r =  - 0.60, p < 0.001), and the Adult Vaccine Hesitancy Scale (r =-0.53, p < 0.001). Measurement invariance was confirmed across education levels (less than university degree vs university degree or above). Reliability testing revealed strong internal consistency (ω = 0.81, α = 0.80) and adequate precision (SEM = 1.06, SDC = 2.85).Conclusion: The Italian version of PACV-5 demonstrates robust reliability, validity, measurement invariance, and precision for use in public health contexts. Future research should also assess criterion validity and responsiveness to interventions to enhance vaccine confidence and uptake.