Conflict, measles resurgence, and immunisation system collapse in Sudan: a narrative review

Sudan is experiencing one of the most severe measles emergencies in recent decades, driven by the collapse of routine immunisation services amid armed conflict and mass displacement. Using vaccination coverage estimates, case-based surveillance reports, and humanitarian situation reports from the World Health Organisation (WHO), the United Nations Children's Fund (UNICEF), Médecins Sans Frontières (MSF), and the United Nations Office for the Coordination of Humanitarian Affairs (OCHA), this review synthesises evidence on declining measles-containing vaccine (MCV) coverage, the rapid rise in diphtheria–tetanus–pertussis first-dose (DTP1) zero-dose children, and the compounding effects of severe acute malnutrition and overcrowding in internally displaced persons camps and border regions. These intersecting vulnerabilities have increased measles transmission and elevated case-fatality rates, while also heightening the risk of cross-border spread to neighbouring countries. Sudan's experience demonstrates how fragile health systems can rapidly lose immunity gains and underscores the need to prioritise immunisation in conflict settings to safeguard regional measles elimination goals.