Altered liver function test after Covid‐19 vaccines: A retrospective control group study.

Background and Purpose: Liver injury after Covid‐19 vaccine has been described, although the incidence was not well established. We aimed to compare cumulative incidence of new onset liver test alteration after Covid‐19 vaccination, and to compare with an historical control of influenza vaccination. Methods: We conducted a retrospective cohort study which included adults who received at least one dose of Covid‐19 vaccine from January 1 to May 30, 2021 and a control group who received a single dose of influenza vaccine during 2019, in a tertiary medical center from Argentina. Results: We included 29 798 patients in Covid‐19 vaccine group and 24 605 in influenza vaccine group. Liver function tests were performed in 7833 (26.9%) in Covid‐19 vaccine group and 8459 (34.37%) in influenza vaccine group. Cumulative incidence at 90 days of new onset liver enzyme test alteration was 4.7 per 1000 (95% 4.0–5.5) for Covid‐19 group, and 5.1 per 1000 (95% 4.3–6.1) for the influenza vaccine group (p value = 0.489). Two patients in the Covid‐19 vaccine group developed immune mediated liver injury. Conclusions: We found no difference in liver test alteration between groups. These findings support the safety of Covid‐19 vaccines. While we have identified two cases that are consistent with immune mediated liver injury following COVID‐19 vaccination, we believe that the available data is insufficient to attribute them solely to the vaccination. [ABSTRACT FROM AUTHOR]