1. These authors contributed equally to the work and share first authorship.
2. Coordinated Research Centre “EpiSoMI”, Università Degli Studi di Milano, Milan, Italy
3. Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
4. Department of Clinical Sciences and Community Health, Università degli Studi di Milano, Milan, Italy
5. Health Protection Agency of the Metropolitan Area of Milan, Milan, Italy
6. Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
7. General Directorate of Welfare, Regione Lombardia, Milan, Italy