Good piece on the hepatitis cases in kids, speaking with some of the epidemiologists for the CDC's Epidemic Intelligence Service.
Still no breakthroughs in the investigation. But some things are ruled out or unlikely. It is unlikely to be a toxin exposure given the wide geographic dispersal of the cases, and local cases don't have much in common. It is also not connected with the coronavirus vaccine as the children weren't vaccinated.
One hypothesis is that it is related to an adenovirus as many of the cases have tested positive for an adenovirus infection, specifically adenovirus type 41 in the US and UK cases. But too early to rule out other pathogens.
Important to also keep in mind that hepatitis of unknown etiology cases occur each year, so some of the detected cases may not be related to the outbreak. And there may be some detection bias given the attention this has garnered.