CD9 and COVID-19: In these cases, EVs can also carry viral elements, such as proteins or receptors that make the acceptor cell more susceptible to infection, as described for human immunodeficiency virus (HIV),26,27 and similar to the transference of CD9 and ACE2 receptors that has been recently proposed for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19).28