Binary logistic regression analysis showed that the combined use of immunosuppressants (OR: 26.969, 95% CI: 1.569–463.541), CRP ≥8 mg/L (OR: 6,468.029, 95% CI: 43.581–959,935.668), steroid resistance (OR: 100.191, 95% CI: 4.845–2,071.880), infection with gram-positive cocci (OR: 7,580.545, 95% CI: 27.126–2,118,452.938), infection with influenza virus (OR: 69.426, 95% CI: 2.494–1,932.221), and infection with respiratory syncytial virus (OR: 353.681, 95% CI: 5.011–24,963.819) were independent risk factors for severe infections in children with INS. The gene discussed is CRP; the disease is infection.