Uptick in cases of hepatitis in children

In recent months, over a hundred young children - under 5 - across the UK have been admitted to hospital with signs of liver damage. This is called hepatitis. Thankfully most have recovered but some have been life threatening. But, so far, investigators have drawn a blank regarding the cause, although there is speculation that a new infection could be responsible, or it might be a knock-on effect of some of the public health measures used to control Covid-19. Will Irving is a clinical virologist at the University of Nottingham; Chris Smith asked him how this came to light in the first place…

Will - It was first picked up in Scotland where public health authorities noticed that they were receiving an increased number of reports of young children with severe liver damage. Then, the UK health security agency put out an alert and a number of other cases were identified right across the UK. I think, at the moment, we're around about 110 cases. Following the UK raising an alert with the world health organisation, cases have been reported in quite a few countries in Europe, America, and in Japan.

Chris - And this all started when?

Will - The first alarm was raised about three weeks ago, but the cases that we're counting are from the 1st of January this year. To see 110 cases of young children with jaundice in a period of four months is extraordinary. It's a really unusual event. To add to the problem is that we don't know what the cause is.

Chris - So, how are they investigating it, then?

——所有这些孩子将有数量吗investigations. They're usually ill enough to be in hospital, so samples are taken. There are a standard set of viruses which are known to cause hepatitis, but the tests for all of those viruses in all of these children have been negative. An alternative possibility is that there is some kind of toxin these children are being exposed to. That is being investigated. But, at the moment, none of the usual suspects have turned out to be the cause.

Chris - Have those investigating ruled out Covid as a possibility? Because that seems to be responsible for, and capable of, causing pretty much everything as far as I can tell over the last two years.

Will - Well, in terms of direct link, of those hundred odd children in the UK, a small percentage at the time that they presented with their severe illness were infected with SARS-CoV-2 but it's less than a fifth. It doesn't appear that an immediate Covid infection is resulting in the hepatitis. That is not to say that the pandemic and SARS-CoV-2 the virus are not in some way related to this outbreak. It would be quite a coincidence, I think, to imagine that this outbreak happened just at the end of two years worth of pandemic that has nothing to do with it.

Chris - So what do you think that relationship could be then?

Will - It's possible that these children have been infected with SARS-CoV-2 before they became ill and that, in some way, has altered the ability of their immune response to deal with the normal childhood virus infections they would usually be exposed to. Then, you have the huge behavioural change across the entire population we've undergone because of the COVID pandemic. We've been isolating, and there's no doubt that over the last two years the circulation of viruses which are normally very common in the community has been reduced. Last August in the UK, we removed most of the precautions that society was taking, which means that, during the last winter, these children who mostly are between three years and six years old have come out into the community, having had two years worth of isolation, and that maybe in some way they've been exposed this winter to a whole range of different viruses, and that may have caused their immune system to react in some peculiar way, which has resulted in liver damage.

Chris - Presumably we've got samples from these children, or at least a proportion of them, and those will be being tested. So, are there any things coming up in those tests that might point towards what viral causes there are?

Will - There is one lead: that many of these children have been shown to be infected with an adenovirus. Adenoviruses are very common childhood infections. There are many different types of adenovirus, but about three quarters of the children where it's been looked for have been found to be positive for an adenovirus. Now, that's interesting and clearly we can't ignore that, but it has to be said that adenoviruses in otherwise healthy children are not known as a cause of hepatitis. We know viruses mutate over time and that can sometimes alter their behaviour, so there are laboratories that are busy looking at the genetic sequence of these adenoviruses to see if there's anything peculiar. But, at the moment we don't know which is the correct explanation.

Chris - And are the kids okay? I mean, are they recovering?

Will - Yes. Most of the children are spending some time in hospital, being supported and then their liver is recovering. The liver has a very great capacity to recover. And then they're going home. There have been around 10 children where the liver damage has been so great that they've needed a liver transplant. I'm not sure about within the UK, but I think there have been, one or two deaths reported from other countries. So it is potentially serious, but 90% of these children are recovering and going home.