CD81 and COVID-19: Proteomic profilingof SiEVs showed that SARS-CoV-2 colocalizes with a CD81/integrin-richsubpopulation of EVs in the sputum of patients with severe COVID-19.Using a proximity barcoding assay, researchers examined immune-relatedproteins in SiEVs and demonstrated that CD81-regulated EV subpopulationsplay a significant role in pneumonia and the immune response to SARS-CoV-2infection.