1 IRCCS-AUSL of Reggio Emilia, Department of Public Health, Service for Health and Safety in the Workplace, Reggio Emilia 42122, Italy. Electronic address: mricco2000@gmail.com.
2 Health Protection Agency Val Padana, Prevention of Infectious Disease Unit, Mantua, Italy.
3 School of Medicine, University Vita-Salute San Raffaele, Milan, Italy.