Both, severe and mild COVID-19 in comparison to controls shared neutrophil-specific CD177 and HP expression among the most upregulated DEGs, as well as lymphocyte-associated genes such as ABLIM1, NELL2, RCAN3, RORC, BACH2, and KLRB1, among the downregulated genes (Additional file 2: Figure S1B,C). This evidence concerns the gene RCAN3 and COVID-19.