Wang F, Nie J, Wang H, et al. - As there is an occurrence of novel coronavirus (SARS-CoV-2)-infected pneumonia (COVID-19) in Wuhan since December 2019, which rapidly spread throughout China, researchers here investigated the characteristics and clinical significance of peripheral lymphocyte subset alteration in COVID-19. Sixty hospitalized COVID-19 patients were assessed before and after treatment for the levels of peripheral lymphocyte subsets using flow cytometry, and for the association of these levels with clinical characteristics and treatment efficacy. COVID-19 patients showed reduced total lymphocytes, CD4+ T cells, CD8+ T cells, B cells and natural killer cells, and severe cases vs mild cases had a lower level. Findings suggested a significant association of the subsets with the inflammatory status in COVID-19, particularly CD8+ T cells and CD4+/CD8+ ratio. Multivariate analysis revealed independent predictive value of posttreatment decrease of CD8+ T cells and B cells and increase of CD4+/CD8+ ratio for poor efficacy. For COVID-19 severity and treatment efficacy, independent predictive value of CD8+ T cells is thus suggested.