The possible reasons of the difference in the rate of severity of COVID-19 between patients with UC and CD are (1) the majority of registered patients over 60 are patients with UC (Supplementary Fig. 5) and (2) the usage rate of anti-TNFα antibodies in UC and CD patients at the diagnosis of COVID-19 was 18.2% (19/104) and 70.2% (52/74), respectively (Supplementary Table 1). This evidence concerns the gene TNF and COVID-19.