PSMD1 and susceptibility to pneumonia measurement: The anti-S1 IgG was detected in 89.3% (268/300), 63.8% (120/188), 65.8% (104/158), and 59.3% (64/108) of samples from patients without pneumonia, and 94.7% (72/76), 81.1% (43/53), 89.8% (44/49), and 91.7% (33/36) of samples from patients with pneumonia, at 3, 6, 9, and 12 months after diagnosis, respectively.