1. Department of Neonatology, Bambino Gesù Children’s Hospital - IRCCS, Rome, Italy;
2. Department of Pathology, Bambino Gesù Children’s Hospital - IRCCS, Rome, Italy;
3. Dipartimento Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy;
4. Division of Neonatology, St-Luc University Hospital, Catholic University of Louvain, Brussels, Belgium