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Alert Date: 
Tuesday, April 26, 2022 - 4:00pm
Europe, United States

TO: Medical Officers of Health and Associate Medical Officers of Health

FROM: Dr. Barbara Yaffe - Associate Chief Medical Officer of Health

RE: Severe Acute Hepatitis of unknown origin in Children

The purpose of this memo is to make you aware of cases of severe acute hepatitis of unknown origin in children observed in Europe and the United States, update you on actions the Ministry of Health is taking to monitor this situation and request your assistance in sharing information with local primary care providers and paediatricians.

Since October 2021, there have been at least 169 cases of acute hepatitis of unknown origin reported among children up to 16 years of age in countries throughout Europe (UK, Ireland, Denmark, the Netherlands, Spain, Italy, Norway, France, Romania, and Belgium), Israel, and the United States.

These cases test negative for hepatitis viruses A, B, C, D and E and have aspartate transaminase (AST) or alanine transaminase (ALT) levels over 500 U/L. In the United Kingdom, some of the cases reported gastrointestinal symptoms, including abdominal pain, diarrhoea and vomiting, and most cases did not have a fever. Several cases have required liver transplantation and one death has been reported. In both Scotland and the US, none of the children had any underlying health conditions of note. Overall, information regarding the aetiology of these cases is evolving, although adenovirus has been identified in some cases. No other epidemiological risk factors have been identified to date.

In response to the request from the World Health Organization and Public Health Agency of Canada to monitor and report potential cases, the ministry is preparing an Order to public hospitals using legislative authorities of the Chief Medical Officer of Health (a copy of the Order will be shared when available). This Order will require public hospitals to report cases as outlined in the Order to Public Health Ontario. Aggregate information will be shared with the respective health unit should a case be identified in your jurisdiction.

In addition, a memo was sent to primary care providers and paediatricians today (a copy attached); please share this memo with your local providers if possible.

Should your public health unit issue any media alerts, we request they be shared with the Office of the Chief Medical Officer of Health at We will continue to share information with you as the situation evolves.


Dr. Barbara Yaffe, MD, MHSc, FRCPC
Associate Chief Medical Officer of Health