More than three years of conflict in Yemen have resulted in one of world’s worst humanitarian emergencies. People are suffering from direct violence, but also from the spread of disease and malnutrition. A blockade by the Saudi-led military coalition has restricted access to essentials, including food and medical supplies. The public health care system is on the edge of collapse. Here, Doctors Without Borders field worker Heather Thomson talks about what she saw while working in Yemen as a medical coordinator.