CCR1 and COVID-19: To functionally characterize the drug targets of these genes, we conducted a drug-gene interaction analysis and identified 11 genes including CCR1, IFNAR2, IL10RB, and OAS1 were targeted by at least one known drug (Fig. 2D and Additional file 3: Fig. S14), of which some genes including CCR1, IFNAR2, and IL10RB have been reported to be drug targets for treating severe COVID-19 patients [25, 26].