1 Division of Infectious Diseases and Hospital Epidemiology, Children's Research Center, University Children's Hospital Zurich, University of Zurich, Zurich, Switzerland.
2 Pediatric Infectious Diseases and Vaccinology Unit, Department Women-Mother-Child, Lausanne University Hospital, Lausanne, Switzerland.
3 Divisions of Allergy and Immunology, Children's Research Center, University Children's Hospital Zurich, University of Zurich, Zurich, Switzerland.
4 Pediatric Infectious Diseases Unit, Division of General Pediatrics, Department of Woman, Child, and Adolescent Medicine, Geneva University Hospitals, Geneva, Switzerland.
5 Division of Pediatric Infectious Disease, Department of Pediatrics, Inselspital, Bern University Hospital, University of Bern, Switzerland.