Efficacy of single-dose HPV vaccine over no vaccination and standard multiple dose regimen: a systematic review and meta-analysis of available evidence

BackgroundThe logistical and financial challenges posed by the current multi-dose Human Papillomavirus (HPV) vaccines in countries with limited resources, result in low vaccine coverage and thus are big hurdles against effective prevention for cervical cancer. This study compared the efficacy of a solitary dose of HPV vaccine regimen with standard multi-doses. MethodsThe PRISMA guidelines were followed. A thorough search was conducted till January 10, 2024, to identify studies investigating the HPV vaccine's efficacy with single versus multiple doses or no dose. For the meta-analysis, a random-effects model was used, considering heterogeneity with I² statistics. The included studies were also assessed for quality using standard tools. ResultsThree observational studies were included with two randomized controlled trials. The meta-analysis comparing individuals given a single dose of the HPV vaccine to those with no dose, revealed an insignificant RR (risk ratio) of 2.11 (95%CI [0.34; 12.87]) with high heterogeneity, which on adjusting for outlier, became significantly better (RR of 1.09 (95%CI [1.04; 1.14]); I² = 33.6%). The comparison of single-dose with two-dose regimens showed no significant difference, while that with three-dose regimens revealed an RR of 2.21 (95%CI [0.07; 66.28]), with I² = 95%. However, a leave-one-out analysis with two- and three-doses, indicated significantly less protection with single dose, RR of 0.81 (95%CI [0.67;0.98]) and 0.78 (95% CI [0.77; 0.79]), respectively. The included studies and trials had moderate to high quality. ConclusionA single-dose HPV vaccine regimen could offer a potential interim solution in preventing incident HPV infection, especially in resource-limited settings (like LMICs) where simplifying vaccination logistics and reducing costs could significantly enhance vaccine accessibility and coverage. However, more evidence is needed to confirm these results and assess the long-term effectiveness of the single-dose regimen.