Severe acute hepatitis and acute liver failure of unknown origin in children: a questionnaire-based study within 34 paediatric liver centres in 22 European countries and Israel, April 2022

To detect potential concern about severe acute hepatitis in children, we conducted a survey among 50 ERN RARE-LIVER centres. By 26 April 2022, 34 centres, including 25 transplant centres, reported an estimated median of 3-5, 0-2 and 3-5 cases in 2021, 2020 and 2019 and a mean of 2 (range: 0-8) cases between January and April 2022 (mean in 10 large liver transplant centres: 3). Twelve centres reported suspicion of an increase, but no rise. Following a report by the United Kingdom (UK) on 5 April 2022 on the occurrence of cases of severe acute hepatitis in children aged 16 years or under, the World Health Organization (WHO) raised concerns about the possibility of an epidemic [1,2]. By 21 April, 169 possible or confirmed cases were reported fulfilling the WHO case definition [3]. The cause of the hepatitis is unknown but a link to a virus infection has been suggested due to the epidemiological pattern of cases [4,5]. The hepatitis can progress to paediatric acute liver failure (pALF) necessitating urgent liver transplantation to avoid multi-organ failure [6]. We intended to assess whether a rise in incidence of severe acute hepatitis or pALF could be observed between 1 January and 26 April 2022 in comparison to previous years, within the European Reference Network on Hepatological Diseases (ERN RARE-LIVER) [7].