Risk of acute liver injury following the mRNA (BNT162b2) and inactivated (CoronaVac) COVID-19 vaccines

Abstract

Background Case reports of severe acute liver injury (ALI) following COVID-19 vaccination are recently described. We evaluated the risks of ALI following COVID-19 vaccines (BNT162b2 or CoronaVac). Methods We conducted a modified self-controlled case series analysis using the vaccination records in Hong Kong with data linkage to electronic medical records from territory-wide healthcare database. Incidence rate ratios (IRRs) for ALI outcome in the 56-day period following first and second doses of COVID-19 vaccines in comparison to the non-exposure period were estimated, and compared to the ALI risk in patients with SARS-CoV-2 infection. Results Among 2,343,288 COVID-19 vaccine recipients who were at risk, 4,677 patients had the first incident ALI from 23rd February 2021 to 30th September 2021. Number of ALI within 56 days after the first and second dose of vaccination were 307 and 521 (335 and 334 per 100,000 person-years) for BNT162b2, and 304 and 474 (358 and 403 per 100,000 person-years) for CoronaVac, respectively, compared to 32,997 ALI cases per 100,000 person-years among patients within 56 days of SARS-CoV-2 infection. Compared to the non-exposure period, no increased risk was observed in the 56-day risk period for first (IRR=0.800, 95%CI: 0.680–0.942) and second (IRR=0.944, 95%CI: 0.816–1.091) dose of BNT162b2; first (IRR=0.689, 95%CI: 0.588–0.807) and second (IRR=0.905, 95%CI: 0.781–1.048) dose of CoronaVac. Of all ALI cases following COVID-19 vaccination, there were no severe or fatal cases. Conclusion There was no evidence of an increased risk of ALI associated with BNT162b2 or CoronaVac vaccination. Based on all current available evidence from previous studies and our study, the benefit of mass vaccination far outweighs the ALI risk from vaccination and SARS-CoV-2 infection. Lay summary Our study did not find an increased risk of acute liver injury following COVID-19 vaccination. Among the very few observed cases of acute liver injury, they were mostly mild and self-limiting. As acute liver injury is far more common after SARS-CoV-2 infection than following COVID-19 vaccination, benefits of mass vaccination outweigh the risks during this pandemic.