CD8A and severe acute respiratory syndrome: Higher IgG levels against spike protein during acute infection were observed in SARS patients who subsequently died, associated with worse clinical lung injury and pro-inflammatory macrophages, compared to SARS patients who went on to recover [12] In COVID-19 patients, total T cells counts are markedly lower in most patients compared to healthy controls and low CD8 T-cell counts (<165/mcl) are a predictor of higher risk for death [13], [14].