TLR7 and COVID-19: As regards the involvement of DCs in determining SARS-CoV-2 infection susceptibility and COVID-19 severity, experimental data demonstrated that TLR7 plays a critical role through viral single-stranded RNA recognition in the endosomal compartments of pDCs (Moreno-Eutimio et al., 2020; Onofrio et al., 2020; Kim and Shin, 2021; Gabriele et al., 2021).