In a recent study, Kusnadi et al. examined landscapes of the SARS-CoV-2-reactive CD8+ T-cell population in a comparison with influenza A virus (IAV)-reactive and respiratory syncytial virus (RSV)-reactive CD8+ T-cell populations by scRNA-seq analysis.1 First, they isolated each virus-reactive CD8+ T-cell population from the peripheral blood mononuclear cells (PBMCs) of patients with COVID-19, or healthy donors via modified antigen-reactive T-cell enrichment (ARTE) (Fig. 1). Here, CD8A is linked to COVID-19.