Top suspects are both viruses: Sars-Cov-2 (COVID-19) and adenovirus 41. But the real cause could just as easily be something else that hadn’t been detected yet. It’s just too early to be certain.
I don’t see why sar-cov-2 would be suspect given it has been running around for a good 2 years already. Unless there is a suspected lower base rate and the sheer speed at which BA.1/2 rips through the population.
1) Many of these hepatitis patients tested positive for Sars-Cov-2 when they arrived at the hospital for hepatitis.
2) Sars-Cov-2 is changing fast. Just in the last few months it has changed substantially several times. Increased hepatitis risk in kids might be one of those changes.
3) The usual causes of hepatitis were not present, and no better explanation has been found yet.
Investigation still in progress. Might be one of these two viruses. Might be something else that hasn’t been detected yet.
Bacteria occasionally intermingle and swap DNA. Most such mutations are not viable, but occasionally you end up with the odd survivor.
This gets more interesting with viruses in the mix. When two viruses infect the same host that later gene transfers items genes the viral payload can end up joining.
It’s a weird, fascinating, and somewhat horrifying (conceptually) process.