Since the start of the year, at least 111 children in the UK have been identified with acute liver inflammation that does not appear to be caused by the group of hepatitis viruses that would have been a more likely culprit. Many more cases have been announced in the US and other countries around the world.
About three quarters of 53 children tested for adenovirus in the UK came back positive. In contrast, the virus that causes Covid-19 was found in just one-sixth of the children tested – in line with levels of community transmission in the UK.
Adenoviruses are a large family of viruses that can spread from person to person and cause a range of illnesses, including the common cold, pink eye, and gastroenteritis. They are rarely reported as a cause of severe hepatitis in healthy people.
But these cases of hepatitis come as the spread of the adenovirus has escalated in recent months, along with other common viruses that have increased with the end of Covid-19 prevention measures and behaviors that kept most germs at bay.
After a dramatic decline during the pandemic, documented cases of adenovirus have returned and are now at a higher level than the UK saw before Covid-19.
Although studies are circling around adenovirus, it’s still unclear how it might cause liver inflammation. Experts say the virus may be just one factor leading to these cases when it happens alongside something else.
Experts say another possibility could be timing. Children who would normally be infected with minimal symptoms as babies may have more severe reactions to the viruses now that they are older.
British scientists have their sights set on a specific type of adenovirus due to blood sample data, but they will need to look at its genetic makeup for confirmation.
According to the UK Health Security Agency, the majority of these are children under the age of 5, with a median age of 3, and only “a small number of children over the age of ten are studied”. Dozens have recovered and no deaths have been reported in the UK, but 10 children required a liver transplant.
Brenda Goodman of CNN contributed to this report.