1 Department of Infectious Diseases, Nanjing Drum Tower Hospital, the Affiliated Hospital of Nanjing University Medical School, Nanjing, Jiangsu, China.
2 Institute of Viruses and Infectious Diseases, Nanjing University, Nanjing, Jiangsu, China.
3 Division of Gastroenterology and Hepatology, Stanford University Medical Center, Palo Alto, California, USA.
4 Department of Epidemiology and Population Health, Stanford University Medical Center, Palo Alto, California, USA.