C5AR1 and COVID-19: The timing of the inflammatory phase of COVID-19 that usually occurs in the second week of illness58,59, together with the increased expression of immunoglobulin genes that we observed (e.g., IGKV1D-13, IGHV3-43, IGLV4-3, IGLV3-16, IGLV3-10) may suggest that immunoglobulin, directed at either viral or modified self-antigens, may be involved in neutrophil and macrophage activation through Fc-gamma receptors or complement mediated activation, genes related to which are upregulated in severe disease (e.g., FCGR2A, FCGR3B, FCGR3A, CR1, C3AR1, C5AR1).