Development and Initial Validation of a Multidimensional Instrument for Assessing Determinants of HPV Vaccine Readiness and Uptake Among Caregivers in Pakistan: A PLS-SEM Approach

Background: HPV vaccination coverage in Pakistan is extremely low, and there are complex psychosocial, cultural, and logistical barriers that currently impede vaccinations. There is no validated measurement tool that is appropriate to the context to measure these determinants systematically. Objective: To develop and validate a multidimensional instrument measuring important factors associated with HPV vaccine uptake and readiness in Pakistan through partial least squares structural equation modelling (PLS-SEM). Methods: A cross-sectional survey was administered to caregivers of girls aged 9–16 years, recruited via purposive/convenience sampling from schools, EPI sites, and household outreach in three Punjab/ICT districts (Rawalpindi, Islamabad, Bahawalpur) during September–November 2025, coinciding with Pakistan’s national HPV vaccination campaign (700 initial responses; 639 retained after screening). The instrument comprised 75 initial items across six constructs: thinking and feeling, social processes, motivation, practical issues, cultural integration, and the vaccination uptake composite index (a composite index of actual vaccination receipt, intention, perceived importance, and perceived access). The measurement model was evaluated for indicator/construct reliability, convergent validity (AVE), and discriminant validity (HTMT, Fornell–Larcker, cross-loadings); the structural model tested direct effects, mediation via motivation, and moderation by practical issues and cultural integration. Results: The number of indicators after model refinement was 27 in six constructs. All outer loadings exceeded 0.70 (range: 0.765–0.939). Cronbach’s α ranged from 0.854 to 0.928, composite reliability from 0.912 to 0.945, and AVE from 0.710 to 0.850. All the HTMT ratios were less than 0.90; Fornell–Larcker and cross-loadings criteria supported discriminant validity. The relationships between thinking and feeling (β = 0.098, p < 0.001) and social processes (β = 0.155, p < 0.001) with vaccination uptake were significantly mediated by motivation. Social and cognitive pathways were moderated by cultural integration. The model accounted for 65.8% of the variance in motivation and 59.4% in uptake of vaccination. Conclusions: The instrument was found to have good psychometric properties and to be suitable suitable for evaluating the determinants of HPV vaccination in conservative, resource-constrained countries such as Pakistan. Findings have direct implications for targeted public health interventions to improve HPV vaccine readiness and uptake.