In coronavirus vaccine development trials, no cases of acute liver injury were reported. However, the number of people included in these trials was insufficient to detect rare side effects after vaccination. Following mass vaccination around the world against COVID-19, cases of acute liver injury (similar to autoimmune hepatitis), with increased laboratory values of liver enzymes, have been described.
To find out how often acute liver damage occurs after vaccination, a study was conducted in Hong Kong and published in the Journal of Hepatology. They included 2,343,288 people who were vaccinated against COVID-19 with the messenger RNA vaccine or with an inactivated coronavirus vaccine.
2,473 cases of acute liver injury were detected with the messenger RNA vaccine and 2,204 cases among those who received the inactivated coronavirus vaccine. Generally, the onset of liver disease occurred about 20 days after vaccination and lasted only about 4 days. 99.2% of the cases evolved favorably and were cured. The incidence was 335 cases per 100,000 people with the messenger RNA vaccine and 358 with the inactivated coronavirus.
In summary, the incidence of liver injury after vaccination against COVID-19 is very low and the course is benign. The benefit of vaccination overwhelmingly outweighs the risk of acute liver damage.