Hajj vaccinations—facts, challenges, and hope

• The impact of changing vaccine policy on infectious disease transmission during the Hajj is reviewed.
• The role of preventive measures during the Hajj is discussed.
• The status of Hajj vaccination studies highlights the knowledge gaps.

SummaryVaccination is an effective preventive measure that has been used in the unique Hajj pilgrimage setting to control the transmission of infectious diseases. The current vaccination policy applied during Hajj is reviewed herein, highlighting the effectiveness of the approaches applied and identifying research gaps that need to be filled in order to improve the development and dissemination of Hajj vaccination strategies.