This is the Guardian.

Over the past few weeks countries around the world have seen an unusual increase in the number of children with severe unexplained hepatitis or inflammation of the liver.

So far, around 200 cases have been reported globally,

in children age from one month to 16 years old,

and more than half of those have come from the UK. This is still a very rare

disease, but the sharp rise has caused concern among scientists and clinicians, not least

because 10% of the children affected have become so ill they've needed a liver transplant.

We don't yet know what's behind this, the UK Health Security Agency and others are investigating

possible causes. So we at the CDC will continue to monitor this event and

work with the teams in the countries reporting cases to see what is behind this.

But there are some clues. As we collectively step out of lockdowns,

other viruses are on the rise again alongside COVID.

So what do scientists think is going on,

and how concerned should we be? I'm Ein Sample, the Guardian Science Editor,

and this is Science Weekly.

Deidry Kelly, you're a professor of pediatric hepatology at the University of Birmingham.

First off, can you just describe to us what severe hepatitis actually is.

Hepatitis means inflammation of the liver, which means it gets

swollen, and it's a non-specific response of the liver to any form of injury.

It could be a drug,

could be a poison, it could be a virus. It is a response to damage and sometimes if the

disease is very severe and the damage is quite extensive.

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