Knowledge, Attitudes, and Behaviors Toward Human Papillomavirus Vaccination Among Adults in Switzerland.

Importance: Human papillomavirus (HPV) vaccination prevents several cancers and genital warts, yet adult uptake in Switzerland remains poorly characterized. In addition to demographic factors, understanding how individuals' knowledge, attitudes, and behaviors (KAB) are associated with vaccine uptake may support strategies to address coverage gaps. Objective: To estimate adult HPV vaccination uptake in Switzerland and evaluate how population-level KAB profiles are associated with vaccination uptake. Design, Setting, and Participants: This nationwide, cross-sectional, population-based survey of adults throughout Switzerland was conducted between September 2023 and September 2024. Adults aged 18 to 45 years were randomly selected from a national residential registry using disproportionate stratified sampling by age, gender, and region. Participants completed a questionnaire on HPV-related KAB, and corresponding HPV immunization data were verified from individuals' personal vaccination records. Exposure: Individual KAB responses regarding HPV disease and vaccination, assessed through standardized questionnaires. Main Outcomes and Measures: The primary outcome was documented receipt of 1 or more HPV vaccine dose according to vaccination records. Latent class analysis was used to define KAB profiles, and multivariable logistic regression used to assess associations with HPV vaccination. Results: Of 41 645 valid addresses, 3847 individuals (9.2%) submitted both a questionnaire and a vaccination record and were included in the analysis. Among 3847 participants (2433 women [weighted 49.1%]; 1997 individuals aged 18-26 years [weighted 26.1%]), 27.2% (95% CI, 25.9%-28.6%) had received 1 or more HPV vaccine dose, with uptake varying by age (58.6% [95% CI, 56.2%-60.9%] for those aged 18-26 years vs 16.1% [95% CI, 14.6%-17.8%] for those aged 27-45 years), gender (42.8% [95% CI, 40.6%-45.0%] of women vs 12.2% [95% CI, 10.8%-13.8%] of men), and region. Three KAB profiles were identified: cluster 1 (2280 participants [52.9%]) showed high HPV awareness and perceived importance, cluster 2 (1099 participants [30.9%]) showed moderate knowledge and low perceived risk, and cluster 3 (468 participants [16.2%]) showed high uncertainty. Vaccination uptake was 41.1% (95% CI, 40.9%-41.2%) in cluster 1, 13.6% (95% CI, 13.4%-13.7%) in cluster 2, and 8.1% (95% CI, 7.9%-8.2%) in cluster 3. Lack of practitioner recommendation was the most common barrier to vaccination across profiles. Conclusions and Relevance: In this cross-sectional study of Swiss adults, in addition to demographic factors, distinct KAB profiles were associated with HPV vaccine uptake. Tailored communication strategies that (1) reinforce practitioner engagement, (2) address risk perception and skepticism, and (3) improve informational outreach may help to address remaining coverage gaps.