BTK and susceptibility to pneumonia measurement: In multivariable analysis, BTK inhibitor (HR=3.5, 95% CI 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 independent risk factors for pneumonia development after COVID-19 infection in patients with lymphoma.