1. Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu 211166, P.R. China
2. Department of Infectious Diseases, Τhe First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, P.R. China
3. Department of Basic and Community Nursing, School of Nursing, Nanjing Medical University, Nanjing, Jiangsu 211166, P.R. China