Global Alert and Response (GAR)

Communicable disease alert and response for mass gatherings

Dr Margaret Chan

Mass gatherings are a stress test for public health. Crowds, and the infrastructures that support them, can be an ideal setting for outbreaks of disease.
... As always, WHO stands ready to support countries seeking technical advice as part of preparedness for the stress test of mass gatherings.

Lancet Conferences: Mass Gathering Medicine, 23-25 October 2010
Dr Margaret Chan, Director-General of WHO

Even if the existing health services and other support services of the host community has adequate capacity to manage the regular disease burden affecting its own population (including occasional outbreaks), the influx of large numbers of people attracted to a mass gathering (MG), together with the infrastructural changes needed to support the event, can place severe strains on such services, compromising the ability to detect a developing problem and carry out an effective response.

If the gathering draws visitors from different nations, regions and cultures, the risk of potential importation or international spread of infectious disease presents additional challenges – as do many of the issues inherent in dealing with a sudden increase in a vastly more culturally and linguistically diverse population.

The Global Alert and Response department of the World Health Organization (WHO) has provided support to Member States in hosting mass gatherings on several occasions in the past, and regularly receives numerous requests for technical support from countries organizing large mass gatherings.

The mass gatherings team within the WHO can provide guidance that is appropriate to the needs of event organizers and local and national authorities. This includes a number of planning, management and response tools to help determine infectious disease risks in relation to mass gatherings. In addition, WHO offers the support of an international advisory network on mass gatherings, composed of technical experts from around the world, whose expertise can be brought to bear on particular issues or events on request. If you have any questions or concerns regarding a planned event, please contact

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