Among convalescent COVID-19 patients, for TRA, the most frequently used gene segments were TRAV12-3 and TRAJ42 in either CD4+ T or CD8+ T cells (Figure 3A), while the frequencies of TRBV23-1 and TRBJ2-7 were significantly higher for TRB (Figure 3B). The gene discussed is CD4; the disease is COVID-19.