Importantly, the frequency of naïve CD8+ T cells (CCR7+CD45RA+) was two-fold lower in the patient with severe disease compared to the patient with mild disease, while a remarkably higher frequency of terminally differentiated TEMRA (CCR7−CD45RA+) CD8+ T cells was observed in both moderate (54.2%) and severe (51.9%) COVID-19 compared to in mild COVID-19 (19.0%). Here, CCR7 is linked to COVID-19.