Abstract
Background A variety of intervention strategies to improve Human Papillomavirus (HPV) vaccination rates in adults exist; however, they have shown varying efficacy and inconsistent outcomes. Purpose This meta-analysis tested the efficacy of HPV vaccination interventions for adults in increasing vaccine intentions, rates of initiation of the vaccine series, and completion rates. The study also tested potential moderators (intervention strategy, theory-based versus nontheory-based interventions, race/ethnicity, gender, study quality) of relationships between intervention receipt and vaccine intentions. Method Electronic databases (PsychINFO, Web of Science, Scopus, EBSCO, JSTOR, PubMed) were searched for English-language articles published up to September 2021. Eligible studies included outcomes of vaccine intentions, receipt of the first dose, or vaccine series completion and included intervention and comparison conditions. Results The search yielded 38 eligible studies reporting 78 effect sizes. Random effects, multilevel, meta-analytic models revealed a significant, small effect of interventions on vaccine intentions (OR = 0.36, 95% CI [0.07, 0.65]); a nonsignificant effect on vaccine initiation rates (OR = 1.29; 95% CI [0.87, 1.91]); and significant effects on vaccine completion rates (OR = 1.58, 95% CI [1.18, 2.11]). Race/ethnicity, gender, intervention strategy, theory-based interventions, and study quality did not moderate the intervention effects on vaccine intentions. Conclusion Evidence supports the efficacy of interventions to increase intentions to receive the HPV vaccine and completion of the HPV vaccine series in adults. However, evidence did not support the efficacy of interventions to increase HPV vaccine initiation. Findings highlight directions for developing more efficacious HPV vaccine interventions for adults.