3 Laboratory of Clinical Microbiology, Virology and Bioemergencies, Ospedale Sacco, Milan, Italy.
4 Infectious Diseases Unit, San Raffaele Scientific Institute, Milan, Italy.
5 Vita-Salute San Raffaele University, 20132 Milan, Italy; Department of Biomedical and Clinical Sciences "L Sacco", University of Milan, Italy.
6 Laboratory of Clinical Microbiology, Virology and Bioemergencies, Ospedale Sacco, Milan, Italy; Infectious Diseases Unit, San Raffaele Scientific Institute, Milan, Italy.