Clinical Infectious Diseases: Open Access

The respiratory syndrome that results from the coronavirus disease 2019 is accompanied by a cytokine storm, the release of numerous proinflammatory factors, and other symptoms. The Delta variant, which has been associated with a high mortality risk, has taken over in many nations. Therefore, comprehension of the immune responses linked to COVID-19 lineages may help in the creation of therapeutic and diagnostic approaches. The severity of COVID-19 was correlated with innate and adaptive immunological factors and pathways, according to numerous single-cell gene expression studies. Additional research on the features of the host-pathogen response to infection caused by various lineages is needed. Here, we used single-cell transcriptome profiling to identify variant-specific molecular immune factors in venous mononuclear cells from people with various COVID-19 and virus lineage severity. Our research shows that the Delta lineage of SARS-CoV-2 is associated with a large population of monocytes with distinct gene expression signatures, which may suggest immune components for targeted therapy.