Severe acute hepatitis of unknown origin.

At the beginning of 2022, in the United Kingdom, and later in several European countries, a group of pediatric patients who developed acute hepatitis of so far unknown origin was reported. Clinical data include nausea, vomiting, jaundice, and liver failure; some patients require liver transplantation. The affected population is younger than 10 years of age. The probable etiological agent is adenovirus genotype F41, and toxic factors have been ruled out, as well as a relationship with COVID-19. There are several theories to explain this phenomenon, which are being investigated.