Background WHO recommends a one- or two-dose human papillomavirus (HPV) vaccination schedule for females aged nine to twenty years. Studies confirming the efficacy of a single dose and of vaccine modifications are needed but randomized controlled trials (RCTs) are costly and face logistical and ethical challenges. We propose a resource-efficient single-arm trial design that uses untargeted and unaffected HPV types as controls. Methods We estimated HPV vaccine efficacy (VE) from a single arm by comparing two ratios: the ratio of the rate of persistent incident infection with vaccine-targeted and cross-protected types (HPV16/18/31/33/45) to vaccine-unaffected HPV types (HPV35/39/51/52/56/58/59/66) versus the ratio of prevalences of these types at the time of trial enrollment. We compare VE estimates using only data from the bivalent HPV16/18 vaccine arm of the Costa Rica Vaccine Trial to published VE estimates that used both the vaccine and control arms. Results Our single-arm approach among 3,727 women yielded VE estimates for persistent HPV16/18 infections similar to published two-arm estimates from the trial (according-to-protocol cohort: 91.0% (95% CI = 82.9%–95.3%) [single-arm] vs. 90.9% (95% CI: 82.0%–95.9%) [two arm]; intention-to-treat cohort: 41.7% (95% CI = 32.4%–49.8%) [single-arm] vs. 49.0% (95% CI = 38.1%–58.1%) [two-arm]). VE estimates were also similar in analytic sub-groups (number of doses received; baseline HPV serology status). Conclusion We demonstrate that a single-arm design yields valid VE estimates with similar precision to an RCT. Single-arm studies can reduce the sample size and costs of future HPV vaccine trials while avoiding concerns related to unvaccinated control groups. Trial registration ClinicalTrials.gov Identifier: NCT00128661.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.