Taken together, these results demonstrate that, compared to low proportions of severely ill COVID-19 patients and patients with fatal outcomes, significant proportions of both unvaccinated asymptomatic COVID-19 patients and unexposed pre-pandemic healthy individuals (UPPHI) presented significant α-CCCs/SARS-CoV-2 strong cross-reactive CD4+ and CD8+ T-cell responses. Here, CD4 is linked to COVID-19.