In general, this illustrates that there is cross-reactivity among CD4+ T cells for prevalent coronaviruses that affect humans and COVID-19, with CD4+ T cells from COVID-19 patients impartially recognizing both the S1 and S2 subunits of SARS-CoV-2, while the cross-reactive CD4+ T cells recognize the S2 subunit [58]. The gene discussed is CD4; the disease is COVID-19.