Abstract
INTRODUCTION: Administering a single dose of the human papillomavirus vaccine substantially reduces costs and simplifies distribution. However, due to inconsistent findings in the existing research, there is an ongoing debate regarding the efficacy of a single-dose HPV vaccine regimen. Therefore, this systematic review investigated the effects of different HPV vaccine administration frequencies. METHODS: We conducted a comprehensive search in the Cochrane Library, Embase, MEDLINE (accessed via PubMed), and CINAHL databases using MeSH and Emtree terms, with the assistance of a professional librarian. We included articles published until April 2024 without restrictions on publication year. We independently performed screening, data extraction, and quality appraisal using the Risk of Bias 2 for randomized controlled trial. This review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. RESULTS: Six publications derived from four unique randomized controlled trials were included in this review. These studies reported on immunogenicity outcomes from 6 to 132 months after HPV vaccination. Although the total number of participants across studies was 29,415, some studies reported overlapping cohorts and the sample size should not be interpreted as additive. Reported geometric mean concentrations (GMC) for single-dose recipients ranged from 2.17 to 176 EU/mL, and for three-dose recipients from 7.92 to 1045.37 EU/mL, depending on the vaccine type, assay, and follow-up time point. The HPV infection incidence rates were 0.0%-1.8% and 0.0%-0.9%, whereas vaccine efficacy was 53.9%-100.0% and 72.6%-100.0% for 1 and 3 doses, respectively. CONCLUSIONS: The findings indicate that, although single-dose vaccination generates lower antibody levels, it still offers substantial protection against HPV infection. This suggests that a single-dose approach could serve as a practical and cost-effective alternative in resource-constrained settings, addressing economic and logistical challenges associated with multi-dose schedules. TRIAL REGISTRATION: PROSPERO registration ID # CRD42024509046.