O-05 Setting appropriate syndromic surveillance alert thresholds for mass gathering events in Small Island Developing States (SIDS) in the Caribbean

Methods: CARPHA implemented a novel Mass Gathering Surveillance System (MGSS) during the 2024 ICC Men’s T20 Cricket World Cup (CWC) across six Caribbean countries. Adapted from the Tourism and Health Information System (THiS), the MGSS integrated syndromic surveillance, visitor health reports, laboratory data, and environmental inputs to provide real-time situational awareness. Predefined symptoms were grouped into six reportable syndromes, and early-warning thresholds were applied to trigger automated alerts. Thresholds ranged from one case (e.g., undifferentiated fever, fever with rash, neurologic or haemorrhagic symptoms) to two or more cases within 24 hours (e.g., gastroenteritis, fever with respiratory symptoms). When thresholds were met, the system generated immediate alerts to health facilities and national authorities, enabling rapid investigation and response, with recommended crosscountry information sharing to enhance regional awareness.

Results: The 5 key parameters for determining suitable syndromic thresholds for the 2024 T20 CWC include the utilization of Global Evidence, consideration of the Caribbean Context which includes the environmental, economic and social structure of the specific Caribbean country, the Type of Mass Gathering Event as the crowds and behaviours vary between different events, the Local Disease Profile as this will provide an understanding of the current disease burden in the specific country and Locally available syndromic data.

Conclusion: This research focused on mass gathering events, the algorithm used and being proposed is applicable to other settings utilizing syndromic surveillance methodology to manage infectious diseases; including tourism establishments, health centers and shelter surveillance in times of emergency. The work done for the T20 Cricket World Cup in the Caribbean now provides baseline data for future mass gathering events in the Caribbean and provides greater impetus for continued and wider surveillance activity to strengthen the existing system.