Ten children in the UK have required a liver transplant following a recent surge in severe hepatitis cases among young children, with the current total standing at 114 cases across all four UK nations.
A lack of exposure to common adenoviruses due to Covid restrictions during the past two years combined with a recent spike in adenovirus infection as society opens back up is the most likely explanation, experts say.
Adenoviruses are common viruses that can cause a range of symptoms, from common cold-like symptoms, to fever, pneumonia, diarrhea and conjunctivitis. They do not usually cause hepatitis, although this can be a very rare complication of some types of adenovirus infection.
Speaking during an emergency session at the European Congress of Clinical Microbiology and Infectious Diseases in Lisbon on Monday, Dr Meera Chand, incident director for UKHSA’s investigation into the hepatitis surge, said that of 81 cases reported in England so far, 43 children had fully recovered , while 38 were still in hospital. Seven of the transplant cases were in England.
“The cases in England are not known to be connected to each another and are dispersed all over the country,” she said.
The vast majority of cases have involved children aged one to six (median age: three), and have occurred during the past three to five weeks. None of the affected children have died.
A leading hypothesis is that surge in severe hepatitis is a knock-on effect of the pandemic, with lockdowns and other restrictions having meant that many children have had less exposure to common viruses than normal, resulting in an inadequate immune response when confronted with infection as society opens back up.
Adenoviruses are a prime suspect: they are spread through close personal contact, coughing or sneezing, and touching contaminated surfaces.
Of the 53 children with hepatitis in England who have been tested for adenovirus so far, 40 (75%) tested positive. Adenovirus infections among one- to four-year-olds in England are also currently at their highest level compared with any other time during the past five years, Chand said.
“I think our leading hypothesis, given the data that we’ve seen, is that we probably have a normal adenovirus circulating, but we have a co-factor affecting a particular age group of young children which is either rendering that infection more severe, or causing it to trigger some kind of [inappropriate immune response],” said Chand.
Prof Deirdre Kelly, a paediatric hepatologist at Birmingham Women’s and Children’s NHS trust and part of a group working with UKHSA to investigate the cases, said: “It may be due to the fact that children who have been largely isolated are responding to viruses that they would normally have built up an immunity to at an early age or it could be previous infection with Covid that has affected the body’s defense systems.”
Between January and April 2018, the Birmingham centre, which is the largest of three specialist centers in the UK that treat severe liver disease in children, saw six severe unexplained hepatitis cases in children. “In the same time interval this year we saw about 40,” Kelly said. “We don’t have the answer why but it’s likely to be something to do with the pandemic because we never had this before.”
Another is that recent Covid infection could suppress the immune system, making children more vulnerable to serious side-effects from normally fairly innocuous viruses; or that a new, more virulent strain of adenovirus is in circulation, although initial genotyping has found no evidence for this, Kelly said.
Most of the infections appear to involve adenovirus 41F, which usually causes diarrhea, vomiting, abdominal pain and fever.
Cases of severe hepatitis among young children have also been detected in 12 other countries, with at least 169 cases reported to the World Health Organization so far. Most of the reported cases have been in the UK, followed by Spain (13 cases) and Israel (12 cases). Cases have also been reported in the US, Denmark, Ireland, the Netherlands, Italy, France, Norway, Romania and Belgium.