University of Oslo - Division of Emergencies and Critical Care, University of Oslo - Department of Research Support for Clinical Trials, University of Oslo - Oslo University Hospital, University of Oslo - Division of Emergencies and Critical Care, University of Oslo - Department of Immunology and Transfusion Medicine, University of Oslo - Institute of Clinical Medicine, University of Oslo - Institute of Clinical Medicine, Vestre Viken Hospital Trust, Diakonhjemmet Hospital, Sørlandet Hospital, Innlandet Hospital, University Hospital North Norway, University of Stavanger - Stavanger University Hospital, University of Oslo - Institute of Clinical Medicine, Vestre Viken Hospital Trust, University of Oslo - Division of Emergencies and Critical Care, University of Oslo - Oslo University Hospital, District General Hospital of Førde - Section for Rheumatology, Haugesund Hospital, Vestre Viken Hospital Trust, Vestre Viken Hospital Trust, Møre og Romsdal Hospital Trust, Telemark Hospital Trust, Haraldsplass Deaconess Hospital, Sørlandet Hospital, Møre & Romsdal Hospital Trust - Molde Hospital - 8Department of Internal Medicine, Innlandet Hospital Trust, Nord-Trøndelag Hospital Trust, University of Oslo - Department of Immunology and Transfusion Medicine, University of Oslo - Institute of Clinical Medicine, University of Oslo - Department of Immunology and Transfusion Medicine, Trondheim University Hospital, Akershus University Hospital - Department of Infectious Diseases, Lovisenberg Diaconal Hospital - Department of Medicine, University of Oslo - Institute of Clinical Medicine, University of Bergen - Department of Clinical Science, Østfold Hospital Kalnes - Department of Infectious Diseases, University of Oslo - Oslo University Hospital, University of Oslo - Institute of Clinical Medicine, University of Oslo - Institute of Clinical Medicine, University of Oslo - Institute of Clinical Medicine, University of Oslo - Section for Clinical Immunology and Infectious Diseases and University of Oslo - Institute of Clinical Medicine

University of Oslo - Section for Clinical Immunology and Infectious Diseases, Universidad Autónoma de Madrid - Hospital Universitario La Paz. IdiPAZ, Sorbonne University - Institut Pierre-Louis d'Epidémiologie et de Santé Publique, University of Oslo - Institute of Clinical Medicine, University of Lille, affiliation not provided to SSRN, University of Verona, Hospital Universitario Virgen Macarena - Unidad Clínica de Enfermedades Infecciosas, affiliation not provided to SSRN, Université Libre de Bruxelles (ULB), Medical University of Innsbruck, Government of Portugal - Unidade Local de Saúde de São João, affiliation not provided to SSRN, affiliation not provided to SSRN, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, Sorbonne University, University of Oslo - Division of Emergencies and Critical Care, University of Claude Bernard Lyon 1, affiliation not provided to SSRN, University of Pécs, National and Kapodistrian University of Athens, University Hospital Brno, University of Basel - University Hospital Basel, Hacettepe University, Technische Universität München (TUM), Hospices Civils de Lyon - Département des Maladies Infectieuses et Tropicales, Sorbonne University - Institut Pierre Louis d'Épidémiologie et de Santé Publique IPLESP, University of Oslo - Oslo University Hospital, Sorbonne University, University of Oslo - Oslo University Hospital, affiliation not provided to SSRN, Vestre Viken Hospital Trust, Groupe Hospitalier de la Région Mulhouse Sud-Alsace, University of Oslo - Institute of Clinical Medicine, University of Stavanger - Stavanger University Hospital, Hospital Universitario La Paz, Vestre Viken Hospital Trust, University Hospital North Norway, Hospices Civils de Lyon - Service de Médecine Intensive-Réanimation, Akershus University Hospital - Department of Infectious Diseases, Norwegian Institute of Public Health, Sorbonne University, affiliation not provided to SSRN, affiliation not provided to SSRN, affiliation not provided to SSRN, University of Oslo - Department of Immunology and Transfusion Medicine, Hospices Civils de Lyon - Laboratoire de Virologie, University of Nantes - INSERM, University of Oslo - Oslo University Hospital, Norwegian Institute of Public Health, University of Verona - Infectious Diseases, Department of Diagnostic and Public Health, affiliation not provided to SSRN, University of Oslo - Department of Research Support for Clinical Trials and Sorbonne University - Institut Pierre Louis d'Épidémiologie et de Santé Publique IPLESP

University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, Lyon Sud Hospital, University of Lille, Hospital Universitario La Paz, Hospices Civils de Lyon, University of Claude Bernard Lyon 1, Sorbonne University - Institut Pierre-Louis d'Epidémiologie et de Santé Publique, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, University of Nantes - INSERM, University of Nantes - INSERM, University of Oslo - KG Jebsen Centre for B Cell Malignancies, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, University of Oslo - Department of Immunology and Transfusion Medicine, University of Oslo - Institute of Clinical Medicine, Groupe Hospitalier de la Région Mulhouse Sud-Alsace, Groupe Hospitalier de la Région Mulhouse Sud-Alsace, Amiens Picardie University Hospital - Intensive Care Unit, Hospices Civils de Lyon - Service de Médecine Intensive-Réanimation, University of Bordeaux - CHU de Bordeaux, University of Bordeaux - CHU de Bordeaux, Assistance Publique-Hôpitaux de Paris - Service de Réanimation Médicale Et Infectieuse (MI2), Université Paris Cité, Louis Mourier Hospital, Dijon University Hospital - Clinical Epidemiology Unit, University of Nantes - INSERM, Centro Hospitalar Universitário de Lisboa Central, University of Oslo, Vestre Viken Hospital Trust, Vestre Viken Hospital Trust, University of Stavanger - Stavanger University Hospital, University of Oslo - Oslo University Hospital, University Hospital North Norway, Østfold Hospital Kalnes - Department of Infectious Diseases, University of Oslo - Oslo University Hospital, University of Oslo - Institute of Clinical Medicine, University of Oslo - Oslo University Hospital, University of Oslo - Oslo University Hospital, Sorbonne University - Institut Pierre Louis d'Épidémiologie et de Santé Publique IPLESP, Hôpital Bichat - Claude-Bernard - INSERM, IAME Infectious Diseases Department, University of Oslo - Oslo University Hospital, University of Oslo - Division of Emergencies and Critical Care, University of Oslo - Oslo University Hospital, University of Oslo - Institute of Clinical Medicine and University of Oslo - Section for Clinical Immunology and Infectious Diseases

University of Bergen, University of Bergen - Haukeland University Hospital, University of Bergen - Haukeland University Hospital, University of Oslo - Oslo University Hospital, University of Bergen, University of Bergen, University of Bergen, University of Bergen, University of Bergen, University of Oslo - Oslo University Hospital, University of Oslo - Division of Emergencies and Critical Care, University of Bergen, University of Bergen, Western Norway University of Applied Sciences, University of Oslo - Institute of Clinical Medicine, University of Bergen, University of Bergen - Department of Clinical Science, University of Bergen - Department of Clinical Science and University of Bergen - Influenza Centre