This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

(The Hill) – Researchers in the U.K. found evidence linking the recent pediatric hepatitis cases detected around the world to the coinfection of two viruses that normally do not cause severe illness, while also finding no connection to COVID-19.

Earlier this year, health authorities in the U.S., western Europe and Japan noted what seemed to be an increase in pediatric hepatitis cases resulting from an unknown cause. In the U.S. alone, more than 300 cases across 42 states are being investigated, according to the Centers for Disease Control and Prevention.

Many of the children who presented with cases of hepatitis — an inflammation of the liver — also tested positive for adenovirus, a common pathogen that usually does not affect the liver. In the U.S., health authorities said very few of the children tested positive for COVID-19 or had a history of the virus.

Several have had to receive liver transplants due to the incurred damage, though the majority of children affected have fully recovered, with the health outcomes usually good.

Now researchers from University College London (UCL) say they have found a possible link between the hepatitis cases and the common adeno-associated virus 2 or AAV2. The virus was found in 96 percent of cases observed in the studies.

As researchers noted, AAV2 is usually “harmless” and unable to replicate without a “helper” virus, such as an adenovirus or herpesvirus. They believe that the infection resulting from both AAV2 as well as the herpesvirus HHV6 offers the best explanation for what caused the unexplained hepatitis.

HHV6 is an extremely common pathogen, with nearly 100 percent of humans having the virus. This strain of herpes often manifests as a rash and fever in very young children and typically resolves on its own.

“While we still have some unanswered questions about exactly what led to this spike in acute hepatitis, we hope these results can reassure parents concerned about Covid-19 as neither teams have found any direct link with SARS-SoV-2 infection,” said Judith Breuer, professor at the UCL Great Ormond Street Institute of Child Health.

Sofia Morfopoulou, a physician at the Institute of Child Health, noted that while AAV2 was found in nearly all of the cases that were part of the study, it is relatively rare in the general population.