1. Department of Health Sciences (DISSAL), University of Genova, Genoa, Italy
2. Infectious Diseases Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
3. Section of Biostatistics, Department of Health Sciences, University of Genoa, Genoa, Italy
4. Infectious Diseases Unit, Albenga Hospital, Savona, Italy
5. Infectious Diseases Unit, Sanremo Hospital, Imperia, Italy
6. Hygiene Unit, IRCCS Ospedale Policlinico San Martino, Genoa, Italy