Officials in health continue to investigate the sudden rise in liver inflammation and hepatitis among children around the globe.
Although there are many possible causes, it seems likely that the common virus that causes diarrhoea, vomiting, and cold symptoms is at play.
Another factor could be the return to normal social interaction after the pandemic.
Hepatitis is the general term for inflammation of the liver tissue.
It can be caused by a viral infection, but also by chemical, alcohol, drug, and genetic disorders.
Specific viral infections are responsible for the most common forms of liver disease, known as A and E. These viruses are not known to be present in children.
Scientists now focus on one adenovirus, but this virus doesn't often cause severe liver disease.
In Scotland, a "signal" that indicated a slight but uncharacteristic rise in cases among previously healthy young children was first discovered.
This prompted an investigation by UK Health Security Agency (UKHSA), which now examines hospital admissions in England and Wales since January.
The agency is currently investigating at least 163 cases involving children aged under 10 years, with most of the cases involving children younger than 5 years.
Initial symptoms included vomiting and diarrhoea, followed by yellowing of skin or whites of eyes (called jaundice).
Of the confirmed cases, 118 are in England, 22 are in Scotland, 13 in Wales, and 10 in Northern Ireland.
The majority have a milder form of the condition. However, 11 people have had to have a liver transplant.
After the UK began reporting an increase in acute severe liver disease cases, though in relatively small numbers of people, awareness grew in other countries. They also started to look for similar conditions in children.
At least 228 cases of suspected hepatitis have been reported to WHO (World Health Organization) as of May 1. Another 50 cases are currently under investigation, it says.
Most of the species have been found in Europe, including Ireland, the Netherlands and other European countries. However, some may also be present in the Americas and the western Pacific, as well as south-east Asia.
One child died from hepatitis.
Scientists are still trying to determine if there's been an increase in cases of hepatitis among children, or a greater awareness about these cases that would otherwise go undiagnosed in a normal year.
There is no reason for us to believe that the rare liver condition is spreading - it is simply being noticed in children from different countries.
Scientists are now studying the adenovirus, which was found in approximately three quarters of UK children who had hepatitis confirmed.
Adenoviruses can spread easily through close personal contact. They can cause diarrhoea, sickness, and even colds. There are over 50 types.
Scientists are interested in F41, a particular type. AAV2 has been detected in samples by genetic analysis.
According to health officials, adenovirus may be making a comeback after almost disappearing in the first year of the pandemic.
The current surge could be due to its impact on the immune system of young children who have never been exposed to adenovirus before or are not protected against it.
The UK's lab data shows that children are more susceptible to viruses than they were in previous years.
According to UK health officials, the chance of your child getting hepatitis from the virus is "extremely unlikely".
Children with diarrhoea or vomiting symptoms should be kept at home for 48 hours.
It is important to wash your hands frequently when you are interacting with children. This will help reduce the spread of many common infections.
None - the children were not vaccinated.
Covid vaccines in the UK are not available until five years of age. This means that many children with hepatitis wouldn't have been eligible for them.
Nearly 16% of patients were positive for coronavirus (SARSCoV-22) upon admission to hospital. However, because there was a lot of Covid at the time, officials claim this is not unusual.
Officials from the UK Health Service say that they are investigating the possibility of new adenoviruses emerging and looking into previous Covid infections.
It stated that it continues to investigate a broad range of infections and causes.
Research suggests that a small number of Covid-infected children and babies have required treatment in countries like the USA, Brazil, and India for hepatitis. Most of these cases were quickly treated and the patients were discharged within days.
Parents, GPs, and other healthcare workers were asked to be aware of symptoms of jaundice. This is a yellowish tint to the skin that can be seen most clearly in the whites.
Children may also experience hepatitis symptoms like:
