CD8A and COVID-19: Our findings are in agreement with other single-cell studies reporting an enrichment of effector populations with a cytotoxic phenotype (effector CD8+, MAIT and NK T cells) in COVID-19 individuals with milder disease phenotype [55, 56] and further highlight the impact of SARS-CoV-2 ORF8 on cytotoxic cellular responses in COVID-19 (Fig. 5).