1. Department of Respiratory Medicine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510120, P.R. China
2. Department of Pediatrics, Hospital Foshan, Guangzhou, Guangdong 528000, P.R. China
3. Institute of Human Virology, Zhongshan School of Medicine, Sun Yat‑sen University, Guangzhou, Guangdong 510080, P.R. China