The disease spectrum of coronavirus disease 2019 (COVID-19) ranges from no symptoms to multisystem failure and death. Characterization of virus-specific immune responses to severe acute respiratory coronavirus 2 (SARS–CoV-2) is key to understanding disease pathogenesis, but few studies have evaluated T cell immunity. In this issue of the JCI, Sattler and Angermair et al. sampled blood from subjects with COVID-19 and analyzed the activation and function of virus antigen–specific CD4+ T cells. T cells that failed to respond to peptides from the membrane, spike, or nucleocapsid proteins were more common in subjects who died. In those whose T cells had the capacity to respond, older patients with comorbidity had larger numbers of activated T cells compared with patients who had fewer risk factors, but these cells showed impaired IFN-γ production. This cross-sectional study relates activated T cell responses to patient risk factors and outcome. However, T cell response trajectory over the disease course remains an open question.
Diane E. Griffin
The Editorial Board will only consider comments that are deemed relevant and of interest to readers. The Journal will not post data that have not been subjected to peer review; or a comment that is essentially a reiteration of another comment.