Using TCR sequencing of 10 000 CD8 T cells expressing activation markers (CD38 and HLA-DR) sampled from each of the 30 COVID-19 patients and 30 healthy controls, the SARS-CoV-2 infection status was inferred by annotating those TCRs that are expected to react to a SARS-CoV-2 epitope (ROC AUC of 0.84 ± 0.10). The gene discussed is CD38; the disease is COVID-19.