Juul Gouweloos-Trines1,2, Mark P Tyler3,4, Melita J Giummarra5,6, Nancy Kassam-Adams7,8, Markus A Landolt9,10, Rolf J Kleber2,11, Eva Alisic9,12. 1. Impact, National Knowledge and Advice Centre for Psychosocial Care Concerning Critical Incidents, Partner in Arq Psychotrauma Expert Group, Diemen, The Netherlands. 2. Department of Clinical Psychology, Utrecht University, Utrecht, The Netherlands. 3. School of Psychological Science and Monash Institute of Cognitive and Clinical Neurosciences, Monash University, Clayton, Australia. 4. School of Psychology and Public Health, Department of Psychology and Counselling, La Trobe University, Melbourne, Australia. 5. Caulfield Pain Management and Research Centre, Caulfield Hospital, Caulfield, Australia. 6. Department of Epidemiology and Preventive Medicine, Monash University, Clayton, Australia. 7. Center for Injury Research and Prevention, Children's Hospital of Philadelphia, Philadelphia, USA. 8. Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA. 9. Department of Psychosomatics and Psychiatry, University Children's Hospital Zurich, Zurich, Switzerland. 10. Division of Child and Adolescent Health Psychology, Department of Psychology, University of Zurich, Zurich, Switzerland. 11. Arq Psychotrauma Expert Group, Diemen, The Netherlands. 12. Monash University Accident Research Centre, Monash University, Clayton, Australia.