A review of the performance of the early warning alert and response system (EWARS) in conflict-affected Borno State, Nigeria: a five-year descriptive analysis.

Background: The northeastern region of Nigeria has been experiencing a protracted humanitarian crisis, characterized by conflict, displacement, and a severely disrupted health system. The Early Warning Alert and Response System (EWARS) was implemented in 2016 to strengthen disease surveillance in this challenging context.

Methods: This study employed a descriptive design to evaluate the performance of EWARS in Borno State, Nigeria, over a five-year period (2016-2021). The data sources included weekly health facility reports and the EWARS alert log. Key performance indicators, including timeliness and completeness of reporting, were analyzed.

Results: EWARS coverage expanded significantly, reaching 341 health facilities across 25 local government areas. The timeliness of reporting ranged from 6 to 85%, with a median of 65.5% (95% CI: 59-73%). A statistically significant positive Pearson correlation was observed between timeliness and the duration of implementation (r = 0.45, p < 0.001). Completeness of reporting ranged from 42 to 96%, with a median of 68% (95% CI: 62.0-76.25%) and a weaker but significant positive correlation (r = 0.19, p < 0.001). A total of 13,737 alerts were generated, of which 89.6% were verified within 24 hours. However, only 0.1% required an immediate public health response. While systematically recorded data on response activities were limited, verified alerts-particularly for measles and cholera-reportedly triggered vaccination campaigns, case investigations, and WASH interventions.

Conclusions: The EWARS system demonstrated significant operational value in strengthening disease surveillance and triggering early warning alerts in the conflict-affected Borno State. Despite not meeting all national performance targets, the system showed improvements over time and supported early detection and verification of potential outbreaks. Its utility as a first-line surveillance tool is evident, though future efforts should prioritize integrating response documentation and event-based surveillance components to strengthen public health impact assessment.