Presence of smokers at home (aOR 2.11, 95% CI 1.27–3.52, P value = 0.004), CRP level ≥ 50 mg/dL (aOR  6.11, 95% CI  3.86–9.68, P value < 0.0001), RSV (aOR  1.78, 95% CI  1.07–2.96, P value = 0.03) and H. influenzae (aOR  1.66, 95% CI  1.03–2.67, P value = 0.04) PCR detection associated with a higher risk of severe pneumonia; ,. The gene discussed is CRP; the disease is susceptibility to pneumonia measurement.