The chapters present comprehensive information about the biology, diagnosis and treatment of the disease, and are written by experts in the field of world renown. The European Respiratory Society is a partner of the Platform for European Preparedness Against (Re-)emerging Epidemics (PREPARE) (http://www.prepare-europe.eu), which is funded by the European Commission’s 7th Framework Programme for Research and Technological Development (FP7) project. PREPARE aims to harmonise large-scale clinical research studies on infectious diseases, and is prepared to respond to severe infectious disease outbreak rapidly, in order to provide real-time evidence for clinical patient management and inform public health responses. PREPARE is a driving force in this area: it has already launched a range of interventional and observational interpandemic trials, and is working to reduce logistical, regulatory and administrative bottlenecks to speed the rapid implementation of clinical trials. With this initiative in mind, an ERS Monograph on viral diseases is very well timed. The Guest Editors, David S. Hui, Giovanni A. Rossi and Sebastian L. Johnston have worked very successfully to integrate the selected topics into a comprehensive book that presents the current knowledge on viral infection. I would like to thank the Guest Editors and all the authors for their work on this excellent book. I am sure that this comprehensive review will be useful for the clinical practice of a broad range of respiratory physicians. Disclosures: R. Bals has received grants from the German Research Ministerium and the Deutsche Forschungsgemeinschaft. He has also received personal fees from GSK, AstraZeneca, Boehringer Ingelheim and CSL Behrig. vi