More than 160 children have now been identified with sudden onset hepatitis in the UK, of whom 11 have needed a liver transplant.
An update from the UK Health Security Agency (UKHSA) shows an extra 18 cases recorded as of May 3 (compared to April 29), bringing the UK total to 163.
None of the children have died.
The World Health Organisation (WHO) said earlier this week there were almost 300 probable cases of children with severe hepatitis detected in 20 countries worldwide.
Health officials are still investigating the cause of the increase in the severe liver condition but a common virus called adenovirus may be causing the surge following the pandemic, according to the UKHSA.
Adenovirus is the most often detected virus in the samples that have been tested.
However, as it is not common to see hepatitis following adenovirus infection in previously well children, investigations are continuing into other factors which may be contributing, the UKHSA said.
These include previous Covid infection or a change in the adenovirus genome itself.
The most common symptoms in children in the UK are jaundice and vomiting, and the vast majority of cases are in those aged under five.
Dr Meera Chand, director of clinical and emerging infections at UKHSA, said: “It’s important that parents know the likelihood of their child developing hepatitis is extremely low.
“However, we continue to remind everyone to be alert to the signs of hepatitis – particularly jaundice, look for a yellow tinge in the whites of the eyes – and contact your doctor if you are concerned.
“Our investigations continue to suggest that there is an association with adenovirus and our studies are now testing this association rigorously.”