In addition, a t-test analysis revealed an increase in severe COVID-19 patients’ EVs expressing platelet endothelial cell (EC) adhesion molecules (PECAM-1, CD31 + CD41-; p = 0.0452), with a large size effect between patient subgroups (mild vs. severe patients, Cohen’s d = 0.978 and moderate vs. severe patients, Cohen’s d = 0.961). This evidence concerns the gene PECAM1 and COVID-19.