The anti-S1 IgA was detected in 84.3% (253/300), 73.9% (139/188), 70.3% (111/158), and 74.1% (80/108) of samples from patients without pneumonia, and 88.2% (67/76), 86.8% (46/53), 81.6% (40/49), and 86.1% (31/36) of samples from patients with pneumonia, at 3, 6, 9, and 12 months after diagnosis, respectively. Here, PSMD1 is linked to pneumonia.