Erika von Mutius is one of the leading experts in the field of the development of asthma and allergic diseases in childhood. She played a decisive role in coining the hygiene hypothesis, according to which the immune system must be trained in early childhood in order to be protected against asthma and allergies. In large-scale epidemiological studies, she was able to show that children who live on a farm are less susceptible to allergies and asthma than children from the city. For her research, Erika von Mutius received, among others, the Leibniz Prize of the DFG and the Bundesverdienstkreuz. | Erika von Mutius is Professor of Pediatric Allergology at the LMU and Director of the Institute for Asthma and Allergy Prevention (IAP) at Helmholtz Zentrum München. | Jonathan Grigg is Professor of Pediatric Respiratory and Environmental Medicine at Queen Mary University London.