The pandemic of the severe acute respiratory syndrome coronavirus 2 (COVID-19) has brought enormous challenges to children at schools worldwide . In early 2020, COVID-19 pandemic forced the Hong Kong government to lock down all the kindergartens and primary schools in Hong Kong district. The young children have to stay at home for online courses, enhancing the family burden to care for them as well as decreasing their social activities. Up to the early spring semester of 2020, COVID-19 pandemic has eased in Hong Kong. All the online courses returned to normal face-to-face classes. The children in all the kindergartens and primary schools were required to wear face masks back to their schools. However, outbreaks of upper respiratory tract infections (URTI) were recently reported in the wearing masks of young children in Hong Kong kindergarten and primary schools. Even though these children with URTI were not found to have caught COVID-19, the government considering the pressures from the COVID-19 crisis and winter flu season declared that Hong Kong kindergartens were closed and all the face-to-face lessons from the first grade to the third grade were stopped in the primary schools for two weeks.