CD4 and COVID-19: In the work by Duarte-Neto et al. [22], the immunohistochemical assay carried out on lung samples obtained from 10 COVID-19 cases revealed a difference in the abundance of both CD4+ and CD8+ T lymphocytes depending on the DAD phase: few CD20+ B lymphocytes were observed in all cases, while CD4+ and CD8+ T lymphocyte infiltrates ranged from scarce in cases with exudative DAD, to moderate in cases with fibroproliferative DAD.