A03 - The Ethics of Placebo Controls in Vaccine Clinical Trials

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In May 2025, the FDA began requiring placebo-controlled trials for new vaccines and updates to existing vaccines, marking a major shift from past practices that allowed reliance on prior efficacy data—such as with annual flu or updated COVID-19 vaccines. This change raises ethical questions, as accepted standards limit placebo use to situations with no proven intervention, minimal risk, or strong methodological justification without serious harm. Is this requirement ethical given the challenges of large trials and the role of vaccines in preventing serious illness? Could stronger evidence justify the risk? This session will examine these issues and guide HRPPs and IRBs in navigating this new landscape for vaccine research.