Validation of the Microarray Patch for Vaccination (MAPVac) scale to measure the perceptions of safety, usability, and acceptability

Introduction: Vaccination is a crucial element of public and population health. Microarray patches (MAPs) may improve vaccine uptake due to reduced pain, being needle-free, enhanced thermostability, and potential for self or lay administration. We aimed to validate a scale that measures perceptions of MAP vaccine safety, usability, and acceptability in adults aged 18+. Methods: This study followed the three phases of scale development and validation. Phase 1 comprised a literature review and key stakeholder cognitive interviews (n = 10) to identify potential and additional scale items. Experts (n = 14) scored the draft scale for face and content validity. In phase 2 further cognitive interviews (n = 27) and exploratory factor analyses determined content validity, informing the addition, adjustment, or deletion of draft items. In phase 3 reliability testing was undertaken by administering two online surveys at least two weeks apart to determine the consistency of participant scores across time and to examine internal consistency. Results: A draft 32-item scale was developed and assessed by experts and key stakeholder cognitive interviews. The final ‘MAPVac’ scale consisted of 20 items. A total of 206 participants from the general public completed online surveys across Australia and New Zealand (n = 92, 44.7 %), Canada (n = 87, 42.2 %), and the United Kingdom (n = 27, 13.1 %). A four-factor model was determined by exploratory factor analysis, which encompassed general positive attitude questions around MAP vaccination achieving its desired outcome, MAP delivery, self and lay administration, and side effects including perceived discomfort. The MAPVac scale demonstrated high internal consistency (Cronbach's alpha = 0.90) and considerable repeatability, with all scale items demonstrating moderate positive correlations at both administrations (Spearman's r = 0.40–0.61). Conclusion: The MAPVac scale is a reliable and valid approach to assessing MAP vaccines' social and behavioural aspects. This scale may assist vaccination programs in developing effective strategies for integrating MAPs and overcoming barriers to vaccination.