Logistic regression analysis revealed that the independent risk factors for severe infections were the combined use of immunosuppressants [95% confidence interval (CI):1.569–463.541, P = 0.023], steroid resistance (95% CI: 4.845–2,071.880, P = 0.003), C-reactive protein (CRP) ≥8 mg/L (95% CI: 43.581–959, 935.668, P = 0.001), and infections caused by GPB (95% CI: 27.126–2,118, 452.938, P = 0.002), influenza (95% CI: 2.494–1, 932.221, P = 0.012) and RSV (95% CI: 5.011–24 963.819, P = 0.007). This evidence concerns the gene CRP and influenza.