General information
There were three boys, six girls and their 14 families admitted to Jinan Infectious Disease Hospital of Shandong University were investigated in this study. The youngest of the nine children was a pair of eleven-month-old twins and the oldest is nine years and 9 months old (mean age was 4.5 years, median age 3.5 years, Table 1). There were 16 families were infected by SARS-CoV-2, and 14 adults were enrolled in this study (two patients hospitalized in another hospital). The 14 patients consisted of 8 males and 6 females with a mean age of 42.9 years (median age, 37 years [range, 30–72 years]).