Quantifying HIV transmission in the context of armed conflict in the Tigray Region, Northern Ethiopia: a dynamic risk...

The two-year armed conflict in the Tigray Region of Northern Ethiopia (2020-2022) created a humanitarian crisis marked by widespread sexual violence, healthcare disruption, and displacement of health personnel. However, reliable epidemiological evidence on the contribution of conflict-related sexual violence to HIV transmission remains scarce. This study addresses this gap by quantifying the impact of conflict-related rape on HIV incidence and prevalence in Tigray. A dynamic risk equation model was developed to capture HIV transmission during conflict. In this framework, conflict intensity influences key transmission drivers, including rape prevalence, number of perpetrators, trauma severity, reduced post-exposure prophylaxis (PEP) use, and healthcare service degradation. Data from the Central Statistics Agency of Ethiopia, UNAIDS regional estimates, World Health Organization, Ethiopian Public Health Institute, and relevant literature were used. Uncertainty analyses were conducted, complemented by global sensitivity analysis and numerical simulations. This model-based study indicates that mass rape could cause a median of 122 (interquartile range, IQR: 13-681) new HIV infections, indicating conflict-related mass rape could cause a median increase of 13.8% (IQR: 1.9%-62.5%), while the median increase in prevalence could be 0.002% (IQR: 0.00027%-0.0089%). These results suggest the increase in incidence due to rape is epidemiologically notable though the effect on population prevalence is small, reflecting that escalating conflict intensity characterized by increased rape frequency, declining health system capacity, and reduced PEP coverage further amplifies HIV transmission. Integrated strategies, including prevention of sexual violence, timely PEP access, and mobile health services, are essential to mitigate HIV transmission. Humanitarian agencies and conflicting parties should act on both public health and human rights grounds.