Dr Saber Yezli is the Head of Research at the Global Centre for Mass Gatherings Medicine, a WHO collaborating center. A pioneer in the emerging field of mass gatherings health, Dr Yezli started his career in the area of infectious disease to later expand to public health, with particular interest in mass gatherings and mass gatherings health. In recent years, Dr Yezli led numerous multicenter/multinational research projects in the area of mass gatherings health, especially in relation to Hajj. Dr Yezli is the author/co-author of over 85 peer-reviewed publications and numerous book chapters, abstracts and invited oral presentations.