Acute hepatitis of unknown origin in children

Recent reports of severe acute hepatitis of unknown aetiology in previously healthy children across multiple countries have resulted in health alerts and a race to identify the underlying cause.

By 11 May, around 450 probable cases of acute hepatitis of unknown cause had been reported worldwide,1 with 163 in the UK by 3 May.2 Affected children were aged between 1 month and 16 years, although more than three quarters of those in the UK were under 5 years and those in the US had a median age of 2 years.2 Eleven children have died so far, and 31 have been reported to require liver transplants (11 in the UK, 5 in Europe, and 15 in the US).34 Gastrointestinal symptoms are common,245 including jaundice (71%), vomiting (63%), pale stools (50%), and diarrhoea (45%). Fever (31%) and respiratory symptoms (19%) are reported less often.6 Most affected children have not received a covid-19 vaccine.