The threat of meningococcal disease during the Hajj and Umrah mass gatherings: A comprehensive review.

The Hajj and Umrah mass gatherings represent many of the risk factors for meningococcal disease and have historically been associated with both local and international outbreaks of the disease. The implementation of strict preventative measures including mandatory meningococcal vaccination with the quadrivalent (A,C,Y,W) vaccine has prevented pilgrimage-associated meningococcal outbreaks and significantly reduced the incidence of the disease at these events. However, meningococcal disease remains an important public health threat at the Hajj and Umrah due in part to the evolving nature of the disease, characterized with diverse and varying geographic trends, fluctuations in incidence and shifts in serogroups and genotypes. In addition, the current Hajj and Umrah meningococcal disease preventative measure do not protect against all invasive serogroups and do not necessarily affect carriage and transmission as the polysaccharide vaccine is still widely used. As a consequence, these events are still susceptible to outbreaks of the disease including those due to serogroups not included in the required vaccines such as serogroups B and X. In this context, despite the global decline in incidence of meningococcal disease, including that cause by serogroup B, the increased predominance of serogroup B disease in many countries, including countries with large Muslim populations, and the emergence of serogroup X in the African meningitis belt, are particularly concerning. Continued and strict surveillance of meningococcal diseases nationally and globally, especially in Muslim countries, is essential in detecting, understanding, and predicting the changes in the epidemiology of the disease and informing appropriate prevention and control strategies during these events. The current meningococcal disease preventative measures for Hajj and Umrah should continue to be strictly implemented, reviewed regularly and updated in accordance with changes in the epidemiology of meningococcal disease and availability of new preventative tools including new vaccines.