IL22 and COVID-19: As IL-22 plays critical functions in epithelial barrier integrity and ILCs are identified as the major source of IL-22 in response to lung pathogens stimulation (98), further studies are urgently needed to assess their exact roles in SARS-CoV-2 infection since current results regarding IL-22 and ILCs in COVID-19 individuals are obtained via analysis of blood periphery (Figure 4).