CD4 and COVID-19: Furthermore, vaccine-inducedimmunity might be different from natural immunity; vaccines may not induce the same T cellresponses as a true SARS-CoV-2 infection does [24].Studies have accumulated evidence of more broadly dysregulated immune function during viralinfection [25], and consistently, we also observeddecreased CD4+ T cell counts in five adult cases, and decreased CD8+ Tcell counts in two critical COVID-19 patients (Tables S4 and S5).