1. Department of Infectious Disease, Children’s Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Chongqing Key Laboratory of Pediatrics, Chongqing 400014, China
2. Department of Epidemiology, School of Public Health, University of Michigan, M5124 SPH II, 1415 Washington Heights, Ann Arbor, MI 48109, USA