Polio Provocation: Solving a Mystery with the Help of History

During the summer of 1951, a medical mystery in the USA erupted into a crisis, stimulating professional debate and public anxiety. The issue was polio provocation, a health risk facing unvaccinated children in polio endemic regions. Leading specialists were at a loss to explain the condition. As the poliovirus was widespread before the discovery of an effective vaccine in 1955, evidence that some paediatric injections could incite polio infection and paralysis led to extraordinary shifts in health policy and calculated efforts to mitigate the risk.