IFIH1 and COVID-19: SARS-CoV-2 infection also increases the expression of TLR2 and other molecules, such as melanoma differentiation-associated gene 5 (MDA5), ACE2 and interferon regulatory factor 3 (IRF3) (Mohanty et al., 2021; Yang et al., 2022), and the expression of TLR2 is positively associated with the severity of COVID-19 (Zheng et al., 2021).