Risk-targeted interventions for measles control- Lessons from an emergency response project in the Katanga Region, Democratic Republic of the Congo (2021-2023)

The Urgepi project is a measles emergency initiative implemented by Medecins Sans Frontieres Operational Centre Paris (MSF-OCP) in the Katanga region of the Democratic Republic of Congo, a setting characterized by recurrent measles epidemics with substantial public health impact. To maximize impact, the project employs a risk-targeted approach directing resources to selected health zones to strengthen surveillance, implement preventive vaccination, and ensure timely epidemic response. This study presents the Urgepi approach, and, based on surveillance data from 2021-2023, evaluates the effectiveness of targeted preventive activities, explores strategies for prioritizing interventions amid multiple alerts, and assesses the overall impact of interventions on measles epidemics. Preventive vaccination successfully averted epidemics in six of the nine vaccinated high-risk health zones, while nine of ten non-vaccinated priority health zones experienced large epidemics. In the three vaccinated health zones that experienced epidemics, more locally adapted vaccination strategies would have been required to achieve higher coverage. Regarding the project's approach to prioritize alerts for investigations and interventions, we found that the Urgepi alert prioritization score was positively associated with subsequent epidemic size, suggesting that this approach allowed effective and timely targeting of larger local measles epidemics. Although no clear impact of epidemic response vaccination on case numbers was observed, likely due to biases introduced in case reporting through provision of free case management, a 50% reduction in the median epidemic duration was recorded. In conclusion, the findings demonstrate the effectiveness of the Urgepi project's risk-targeted approach for measles prevention and control and highlight the importance of timely and context-specific interventions.