While the acute impact of the coronavirus disease 2019 (COVID-19) pandemic has waned, implications for clinical trials remain. In particular, guidance for evaluation of elevated liver tests due to COVID-19, its treatments, and COVID-19 vaccination is lacking. The IQ DILI Initiative, composed of experts from academia, regulatory agencies, and industry herein propose recommendations to address this gap. Extensive literature review was conducted and structured discussions were held between IQ DILI industry members, regulators, and academic experts in hepatology and DILI. Liver-related manifestations in nonhospitalized patients with COVID-19 are highly varied. Evidence of liver injury may occur after COVID-19 symptoms resolve and testing is negative. Treatments for COVID-19 may cause liver injury or alter pharmacokinetics. COVID-19 vaccination has been associated with rare but clear hepatotoxicity, typically consistent with drug-induced autoimmune-like hepatitis, although other presentations, severity, latency, and time to resolution have been reported. Liver injury occurred with mRNA and viral vector vaccines, and in individuals with and without underlying autoimmune or liver diseases. Drug developers and investigators should be aware of the potential liver-related manifestations related to COVID-19, its treatments, and COVID-19 vaccination, as this may impact study eligibility and causality assessment during a trial. COVID-19 testing should be considered part of DILI causality assessment, as a positive test may prevent premature termination of the investigational drug. Since clinical trial participants may not consider vaccinations in their medical history, specific inquiry about their receipt is important when liver tests are abnormal during screening and as part of DILI causality assessment.
© 2025. The Author(s).