A Mysterious Outbreak in Children Possibly Linked to Adenovirus

A worldwide outbreak of liver disease of unknown origin is affecting young children around the globe, and has sent medical experts scrambling to uncover the cause.

These cases of hepatitis, an inflammation of the tissue in the liver, are primarily afflicting children between 2 and 5 years old, with the first cases appearing last fall. The symptoms start with gastrointestinal issues such as abdominal pain, diarrhea and vomiting, followed by the onset of jaundice. At least 194 children across more than a dozen countries have been affected, with at least 114 cases recorded in the UK alone, and 18 cases in the US across seven states; at least 17 patients have required liver transplants, and at least one child has died.

Prior to contracting the illness, all of the patients were considered healthy with no immune system issues or significant comorbidities, and no epidemiological links can be established between each of the cases; none of the patients in the US had been recorded as having contracted COVID-19.

Although medical experts have numerous theories as to what is causing the mysterious illness, an emergency briefing document from the UK Health Security Agency has ruled out a number of potential causes:

• Although the symptoms are consistent with hepatitis, the patients tested negative for the viruses that cause hepatitis A, B, C, D and E.
• With most of the children being five years or younger, an adverse reaction to COVID-19 vaccines has been ruled out, as they are not eligible to receive the vaccines.
• With the majority of patients being over the age 2, their mothers would not have been pregnant during the COVID pandemic.
• The adenoviruses used as vectors in some COVID vaccines, such as the Johnson & Johnson and AstraZeneca-Oxford vaccines, are inactive and cannot cause disease in their recipients.
• No common exposure to potential toxins, contaminated food, drugs or other environmental factors has been identified thus far.

Additionally, although the idea that reduced immunity resulting from “restricted social mixing” during the COVID-19 pandemic may be behind this illness has been put forward, these cases are also being recorded in regions that weren’t subject to such restrictions, and its appearance doesn’t seem to match the varying patterns of restrictions imposed in regions that were.

At this point the prime suspect behind this outbreak is human adenovirus type 41; although adenoviruses typically cause problems in the upper respiratory tract—they are the type of virus behind the common cold—adenovirus 41 can also cause gastroenteritis, an inflammation of the stomach and intestine, and is so far the most common adenovirus detected in the affected children.