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Acute hepatitis of unknown origin in children

BMJ 2022; 377 doi: (Published 17 May 2022) Cite this as: BMJ 2022;377:o1197
  1. Muge Cevik, clinical lecturer1,
  2. Angela L Rasmussen, professor2,
  3. Isaac I Bogoch, associate professor diseases3,
  4. Jason Kindrachuk, Canada research chair4
  1. 1Division of Infection and Global Health Research, School of Medicine, University of St Andrews, St Andrews, UK
  2. 2Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Canada
  3. 3Division of Infectious Diseases, University of Toronto, Toronto General Hospital, Toronto, Canada
  4. 4Laboratory of Emerging and Re-emerging Viruses, Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada
  1. Correspondence to: J Kindrachuk Jason.Kindrachuk{at}

Many leads but few clear answers

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.

Possible causes

Tests for hepatitis viruses A–E have been universally negative. Detailed laboratory investigation by the UK Health Security Agency …

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