Worldwide epidemic information
As of May 26, 2022, 650 possible cases of acute hepatitis of unknown etiology among children fulfilling the WHO case definition have been reported to the WHO from 33 countries in the 5 WHO region, and 99 other cases are awaiting classification. The majority of reported cases (n = 374; 58%) came from the WHO European region (22 countries), with 222 (34%) coming from the United Kingdom, Great Britain and Northern Ireland. Probable cases and cases awaiting classification have also been reported in the U.S. region (n = 240, including 216 cases in the United States), the western Pacific region (n = 34), the eastern region of Asia (n = 14), and the eastern Mediterranean region (n = 5). Compared to previous reports of acute hepatitis of unknown etiology in children, the cases are clinically more severe and require at least 38 (6%) pediatric transplantation to develop a high proportion of acute liver failure, and 9 (1%) deaths have been reported.
European epidemiological data
According to a recent joint surveillance report by the WHO Regional Office for Europe (EURO) and the European Center for Disease Prevention and Control (ECDC), cases arising from EU / EEA countries as of May 20, 2022:
- Three-quarters (75.4%) are under 5 years of age.
- Of the 156 cases for which hospitalization data were available, 22 (14.1%) were admitted to an intensive care unit.
- In the 117 cases for which this information was obtained, 14 (12%) received liver transplants.
- Overall, adenovirus was tested in 181 cases, regardless of sample type, and 110 (60.8%) of them tested positive. The positivity rate was highest in the whole blood sample (69.5%).
- Of the 188 cases tested by PCR for SARS-CoV-2, 23 (12.2%) tested positive. SARS-CoV-2 serology results were found in only 26 cases, of which 19 (73.1%) had positive results.
- Of the 63 cases with COVID-19 vaccine data, 53 (84.1%) were not vaccinated.
Most reported cases do not appear to be linked, and extensive epidemic investigations are under way to identify links between common exposure, risk factors, or cases. Two pairs of cases have been reported as associated with epidemiology in Scotland, and LinkedIn cases have also been reported in the Netherlands. Therefore, human-to-human transmission cannot be ruled out.
An etiology that remains unknown
The etiology of this severe acute hepatitis is still unknown and under investigation.
- Adenovirus has been found in 75% of cases tested in the UK and most of the few samples typed so far have been confirmed for adenovirus type 41. However, the virus has never been associated with such clinics. Pictures in healthy children. This question will be clarified through the expansion of adenovirus screening in other areas outside Europe and the United States and the ongoing UKHSA (United Kingdom Health Security Agency) results communication.
- For adeno-related viruses (or AAVs) Adeno-related viruses In the UK, a small number of cases have been identified, but the virus is not usually pathogenic.
- Estimates of the side effects of the COVID-19 vaccine are not currently supported because most infected children have not received this vaccine.
- Low circulation levels of adenovirus during the Covid-19 epidemic may result in increased susceptibility in young children as a result of the possible emergence of new adenoviruses, co-infection with SARS-CoV-2, or complications of previous SARS-CoV-2 infections. In the activation of super Antigen-mediated immune cells, the method that has been proposed. These assumptions need further investigation.