Abstract Background Religious mass gatherings (MGs) such as Hajj, Umrah, Arba'een, and Kumbh Mela attract tens to hundreds of millions of participants annually, posing unique challenges for infectious disease control, surveillance, and health system preparedness. Methods We conducted a structured comparative analysis of these four MGs, evaluating attendance scale, participant demographics, governance structures, epidemiological risks, and public health response strategies. Data were synthesized from international public health reports, peer-reviewed literature, and national MG health policies. Results Hajj attracts 1.8–3 million pilgrims annually from 180 countries, while Umrah draws ~30 million yearly with similar global diversity. Arba'een hosts 20–22 million participants mainly from Iraq, Iran, and neighboring nations. Kumbh Mela peaks at tens of millions overall, exceeding 50 million on high days, predominantly Indian nationals plus international visitors. Common threats across these mass gatherings include respiratory pathogens, water- and food-borne illnesses, and vaccine-preventable diseases, amplified by crowding and diverse origins. Successful public health responses emphasize pre-event vaccination (e.g., meningococcal ACWY for Saudi MGs), real-time surveillance systems, and multisectoral coordination among stakeholders. Conclusions Comparable yet distinct, these MGs require tailored risk-based frameworks emphasizing leadership, surveillance, prevention, and surge capacity. Our analysis proposes a unified model to strengthen global MG policies and practices, enhancing health security for future events.
Al-Tawfiq et al. (2026) studied this question.