AAV patients with severe COVID-19 infection were more likely to be male (OR 1.921 [95% CI 1.020–3.619], P = 0.043), suffered from worse kidney function (serum creatinine [Scr], OR 1.901 [95% CI 1.345–2.687], P < 0.001), had higher C-reactive protein (CRP) (OR 1.054 [95% CI 1.010–1.101], P = 0.017) and less likely to have evidence of initial vaccination (OR 0.469 [95% CI 0.231–0.951], P = 0.036), and Scr and COVID-19 vaccination were proven to be significantly associated with severe COVID-19 infection even after multivariable adjustment. The gene discussed is CRP; the disease is COVID-19.