The impact of geographically-targeted vaccinations during the 2018-2020 Kivu Ebola outbreak

The 2018–2020 Ebola virus disease (EVD) outbreak in the Democratic Republic of Congo (DR Congo) was the second-largest in history, mainly because of security challenges and community mistrust. This study evaluates the impact of geographically targeted vaccinations (GTVs) as a complementary strategy when traditional measures—contact tracing, ring vaccinations, and antiviral treatments—are insufficient. We develop a novel mathematical model, incorporating key factors such as transmission from the deceased, heterogeneity in susceptibility, migration patterns, and control measures. Numerical simulations reveal that while traditional control measures substantially reduce cumulative cases to 3500 within one year, compared to over 10 million cases without intervention, population movement into high-infection areas intensifies transmission by increasing the pool of susceptible individuals. This highlights the need to reduce the flow of population into high-risk regions. Sensitivity analysis identifies key parameters, including effective contact rate and the rate of movement into areas with high infections, as critical epidemic drivers. Contour plots demonstrate that GTVs in areas with high infections significantly reduce the spread of EVD. Model findings emphasise integrating GTVs and population flow management with traditional strategies to strengthen outbreak responses in conflict-prone regions.