At present, COVID-19 still influences the world as a pandemic infectious disease; Pesce et al. [80] isolated EVs from the plasma of mild and severe COVID-19 patients followed up by proteomics with healthy donors as the control group and observed both mild and severe case-derived EVs to be involved in the upregulation of the immune response for SARS-CoV-2, but differences in the immunomodulatory effects in the activation of immune cells (CD4+T-cell) and acute inflammation, respectively, associated with different protein signatures in EVs. Here, CD4 is linked to COVID-19.