Modeling Infectious Disease Epidemics in Mass Religious Gatherings: A Systematic Review

Like other global mass gatherings, religious pilgrimages, such as Hajj, Arba’een, and the Hindu festival Kumbh Mela, attract millions of pilgrims to gather at specific holy sites on specific dates. During disease pandemics, mass gatherings can become super spreader events, causing exponential growth of infections in multiple regions. Epidemic modeling approaches can be valuable tools for studying the impact of mass gatherings on global health during disease outbreaks. To assess the use of epidemic models at religious pilgrimages, we compile published studies that proposed epidemic models at mass religious gatherings. A review of existing epidemic models at various religious gatherings highlights the role of epidemic modeling approaches in assessing the implications of religious pilgrimages on disease pandemics. All the articles surveyed showed a link between hosting religious gatherings and an increase in the number of cases of the simulated epidemic. In addition, we found that the SEIR mathematical model was the most common type developed with variations in some of the retrieved papers. The results reported in these studies motivate further investigation of the role of epidemic modeling and simulation in estimating the size and geographic scale of infections while hosting religious gatherings. Finally, we believe that this survey article draws attention to the application of epidemic models in the advanced planning of recurrent religious pilgrimages, as it is not feasible to cancel, suspend, or reallocate these pilgrimages. These epidemic models can provide a baseline for policymakers to determine which control measures should be implemented and when.