Multilevel Interventions Aimed at Improving HPV Immunization Coverage: A Systematic Review and Meta-Analysis.

BACKGROUND/OBJECTIVES: Human papillomavirus (HPV)-attributable cancers are a major public health problem worldwide. However, HPV vaccination rates vary significantly and are often not optimal. This study aimed to assess the effects of multilevel interventions on improving HPV vaccination. METHODS: A systematic literature review and a meta-analysis were carried out, taking into account randomized controlled trials. Outcomes of interest were HPV vaccination initiation and completion. A random-effect meta-analysis using the generic inverse variance method was carried out, with a risk ratio (RR) with a 95% confidence interval (CI) as the pooled effect estimate. RESULTS: A literature search identified 15 relevant studies, all conducted in high-income countries. Multilevel interventions significantly improved HPV vaccination coverage and initiation (RR = 1.26, 95% CI 1.16-1.38, p < 0.00001 and RR = 1.14, 95% CI 1.04-1.24, p = 0.004, respectively) compared to usual care. Sensitivity analyses showed that the results remained relatively robust. Subgroup analysis by targeted levels of intervention indicated that multilevel interventions had an effect across all comparisons and outcomes except for HPV vaccination completion for interventions that targeted four levels of influence. CONCLUSIONS: Based on evidence from high-income settings, multilevel interventions are effective in improving HPV vaccination rates. Future studies should expand the focus to areas with limited resources too and aim to provide more detailed data, avoid registering outcomes via self-report, and create sustainable strategies that can persist beyond a study's duration and possibly become part of policies for improving HPV vaccination coverage.