1. Pediatric Intensive Care Unit, Hospital Sant Joan de Déu, University of Barcelona, Passeig de Sant Joan de Déu, 2, 08950 Barcelona, Spain
2. Faculty of Medicine, University of Barcelona, c. Casanova, 143, 08036 Barcelona, Spain
3. Immunological and Respiratory Disorders in the Paediatric Critical Patient Research Group, Institut de Recerca Sant Joan de Déu, University of Barcelona, 08950 Barcelona, Spain
4. Neonatal Intensive Care Unit, Hospital Sant Joan de Déu, University of Barcelona, 08950 Barcelona, Spain
5. Neonatal Intensive Care Unit, Department of Paediatrics, Hospital Germans Trias i Pujol, Autonomous University of Barcelona, 08916 Badalona, Spain
6. Biostatistics, Department of Basic Clinical Practice, University of Barcelona, 08036 Barcelona, Spain
7. Pediatric Infectious Diseases Research Group, Institut de Recerca Sant Joan de Déu, CIBERESP, 08950 Barcelona, Spain