The Hajj Rituals; Agent-based Simulation - AnyLogic Software

Mass gathering events pose a significant risk for the spread of respiratory viruses, such as the SARS-CoV-2 virus that caused the COVID-19 pandemic. During the Hajj pilgrimage, large numbers of people perform rituals and prayers in often-crowded, predefined indoor and outdoor spaces. This creates conditions where respiratory infections can easily spread among pilgrims from over 180 countries, potentially leading to a super-spreading event with global implications. This study focuses on the rituals performed within the Masjid-Al-Haram complex, specifically the Tawaf in Mata'af and Sa'ay in Masa'a Building. Our model allows users to adjust parameters such as the total number of pilgrims, entrance rates, pilgrim speed, and test measures like social distancing and PPE use, along with visual settings. The model also calculates the number of close contacts, based on CDC definitions, as a key factor in COVID-19 transmission. We used a combination of agent-based modeling and discrete event simulation techniques to develop a multiscale simulation model in AnyLogic software. The model simulates pilgrim movement within Masjid-Al-Haram, from entry to completing Tawaf and Sa'ay, and departure. Pilgrims enter from five main gates at a predefined rate, proceed to Mata'af, complete seven rounds, pray outside, then enter Masa'a for Sa'ay (seven rounds), and finally leave through one of the five gates. The model dynamically displays pilgrim count, unique contacts, and disease transmission probability. Evaluating, mitigating, and communicating the risks of mass gatherings are crucial for informed decision-making. Further details of the simulation and findings can be found in the research paper: Tofighi, M., Asgary, A., Tofighi, G., Najafabadi, M. M., Arino, J., Amiche, A., Rahman, A., McCarthy, Z., Bragazzi, N. L., Thommes, E., Coudeville, L., Grunnill, M. D., Bourouiba, L., & Wu, J. (2022). Estimating social contacts in mass gatherings for disease outbreak prevention and management: Case of Hajj pilgrimage. Trop Dis Travel Med Vaccines, 8(1), 19. https://doi.org/10.1186/s40794-022-00177-3