(a–d) Representative flow cytometry plots showing the expression of activation and proliferation markers on CD4+ and CD8+ T cells (top and bottom panels, respectively in a, b), TCR-γδ T cells (c) and NK cells (d: plots shown for NK CD56dim cells) in a healthy control and the COVID-19 patient (at days 23 and 58). The gene discussed is CD8A; the disease is COVID-19.