The transmission routes of SARS-CoV-2, the pathogen of COVID-19, remain still partly unclear (Yang and Duan G, 2020). According to present knowledge (Chinese Thoracic Society and Chinese Association of Chest Physicians, 2021), the main transmission routes of COVID-19 are respiratory droplets from close contacts and aerosols in confined spaces (Rabaan et al., 2021; Schijven et al., 2021). However, there is no evidence to exclude the possibility of other routes of transmission, such as gastrointestinal tract transmission (Jiao et al., 2021).
