Fig. 1.

The association of the severity of COVID-19 with underlying diseases in the patient cohort. a The association of the severity of COVID-19 with comorbidities. The comorbidity group 1 (CG 1) includes chronic hepatitis B virus infection, liver cirrhosis, chronic respiratory diseases, HIV infection, and cancers which are known to impair immunological functions. The comorbidity group 2 (CG2) includes psychological diseases and fatty liver diseases which are primarily not related to host immune functions. The risk to develop severe COVID-19 was shown for patients without known comorbidities (No CG), CG1, and CG2. b The ranges of the ages of patients with and without comorbidities. The means ± SD are given in the graph. Results were tested for significance by Chi square test (a) or t test (b). A P value < 0.05 is considered as significant