Lilly Verhagen is a paediatrician who studies the immune system of the respiratory tract in vulnerable children around the world. By unravelling how antibodies function in the respiratory tract, she hopes to develop new treatments that will speed up children's recovery and reduce the use of antibiotics. For example, our understanding of respiratory infections may be better served by analysing saliva and other samples taken from the respiratory tract than by taking blood samples, which is the current practice in hospitals. Lilly combines patient care with research in the Netherlands, South Africa and the Caribbean. Her international partnerships ensure that precisely the most vulnerable groups of children benefit from her research, and that young researchers have the opportunity to build their international careers.