SARS-CoV-2 shares 82% genome sequence similarity to SARS-CoV and 50% genome sequence homology to Middle East respiratory syndrome coronavirus (MERS-CoV)—all three coronaviruses are known to cause severe respiratory symptoms. Liver impairment has been reported in up to 60% of patients with SARS3 and has also been reported in patients infected with MERS-CoV.4 At least seven relatively large-scale case studies have reported the clinical features of patients with COVID-19.

In this Comment, we assess how the liver is affected using the available case studies and data from The Fifth Medical Center of PLS General Hospital, Beijing, China. These data indicate that 2–11% of patients with COVID-19 had liver comorbidities and 14–53% cases reported abnormal levels of alanine aminotransferase and aspartate aminotransferase (AST) during disease progression (table). Patients with severe COVID-19 seem to have higher rates of liver dysfunction. In a study in The Lancet by Huang and colleagues, elevation of AST was observed in eight (62%) of 13 patients in the intensive care unit (ICU) compared with seven (25%) of 28 patients who did not require care in the ICU. Moreover, in a large cohort including 1099 patients from 552 hospitals in 31 provinces or provincial municipalities, more severe patients with disease had abnormal liver aminotransferase levels than did non-severe patients with disease. Furthermore, in another study,patients who had a diagnosis of COVID-19 confirmed by CT scan while in the subclinical phase (ie, before symptom onset) had significantly lower incidence of AST abnormality than did patients diagnosed after the onset of symptoms. Therefore, liver injury is more prevalent in severe cases than in mild cases of COVID-19.