BTK and susceptibility to pneumonia measurement: In the multivariable logistic regression model, BTK inhibitor (HR=3.5, 1.6–8.0, P=0.003), active therapy (HR=3.3, 95% CI 1.6–6.8, P=0.001), and disease non-remission (HR=2.9, 1.3–6.4, P=0.007) were identified as independent risk factors for the development of pneumonia after COVID-19 infection among patients with lymphoma.