Before matching, most baseline characteristics of the two groups were unbalanced, including age, gender, body mass index (BMI), severity, vaccination doses, concomitant systemic steroid, concomitant antibiotics, comorbidities other than autoimmune diseases, neutrophil, glucose, creatine, glomerular filtration rate, C‐reactive protein, procalcitonin, prothrombin time, activated partial thromboplastin time, cholesterol, alkaline phosphatase, albumin, total bilirubin. The gene discussed is F2; the disease is autoimmune disease.