CCR9 and COVID-19: Therefore, the present study revealed a total of 19 genome-wide risk genes for COVID-19, including ABO, CCR1, CCR2, CCR3, CCR9, CCRL2, CXCR6, DPP9, FYCO1, IFNAR2, LIMD1, LTF, LZTFL1, OAS1, OAS2, OAS3, SLC6A20, VSTM2A, and XCR1.