Single-Arm Trial Design Estimates Efficacy

Nicole Campos looking away from camera with cup in hand.

CHDS faculty Nicole Campos and a team of researchers from the National Cancer Institute, including co-investigators Brian Befano and Li C. Cheung, proposed a resource-efficient single-arm trial design to estimate HPV vaccine efficacy published in the Journal of the National Cancer Institute.

The World Health Organization recommends a 1- or 2-dose HPV vaccination schedule for females aged 9 to 20 years. Studies to confirm the efficacy of a single dose, of vaccine durability, and of vaccine modifications are needed, but randomized controlled trials (RCT) are costly and face logistical and ethical challenges.

In the study, the authors used HPV types that are not targeted and not affected by the vaccine as controls. They estimated vaccine efficacy from only the HPV16/18 vaccine arm of the Costa Rica Vaccine Trial and compared it to published estimates from the RCT that relied on both the vaccine and control arms. The study demonstrated proof of principle that the single-arm design yields valid estimates of vaccine efficacy with similar precision to a RCT, while reducing sample size, costs, and avoiding concerns around unvaccinated control groups.

Learn more: Read the publication, Estimating Human Papillomavirus Vaccine Efficacy from a Single-Arm Trial: Proof-of-Principle in the Costa Rica Vaccine Trial

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