The UK Health Security Agency (UKHSA) has released its fourth technical briefing, which details investigations into an increase in cases of childhood hepatitis

There have been 270 confirmed cases of hepatitis in children aged 10 and under as of July 19. 15 of these children have received liver transplants, and none have died. The number of new cases reported has now decreased.
The technical briefing examines 274 confirmed and possible cases through July 4. Adenovirus is still the most commonly found potential virus in cases. Among the 274 UK cases, 258 were tested for adenovirus, with 170 (65.9 percent) having adenovirus detected.
A case-control study conducted across the United Kingdom discovered a strong link between adenovirus infection and this cluster of cases. Data from routine surveillance show an increase in adenovirus detection and positivity in laboratory reports in young children both before and after those affected by the outbreak reported symptoms. Neither older children nor adults experienced similar increases.
Details of a study conducted by the MRC-University of Glasgow Centre for Virus Research (CVR) and the Royal Hospital for Children in Glasgow are included in the technical briefing. It is a collaboration between Public Health Scotland and the International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) WHO Clinical Characterisation Protocol UK (CCP-UK), and a second collaboration between Great Ormond Street Hospital and the UCL Great Ormond Street Institute of Child Health (UCL GOS ICH) and UKHSA.
The studies used metagenomics to look for other viruses that may have been involved in the outbreak by studying samples taken from those affected. Both studies found adenovirus-associated virus 2 (AAV2) in the majority of cases studied, but it was absent (or at low levels) in samples taken from people unaffected by the outbreak as part of the study (known as controls). AAV2 does not typically cause illness and requires a ‘helper’ virus to divide in the body. There are also some preliminary findings that suggest that differences in people’s immune systems may play a role. It is too early to say how these findings interact and which ones are important in the context of the outbreak.
The possible role of coronavirus (COVID-19) has been investigated further – In the two weeks preceding hospital admission, 4.4 per cent of cases tested positive for SARS-CoV2, compared to 4 per cent in a random age-matched sample of A&E admissions. Cases with COVID-19 positive tests at any point prior to hepatitis symptoms were studied to determine whether prior COVID-19 infection played a role. This study discovered that 11.9 per cent of cases had a positive COVID-19 test, compared to 15.6 per cent in the random sample – the difference is not statistically significant. Furthermore, blood samples from cases revealed no statistically significant difference in the presence of SARS-CoV2 antibodies when compared to age-matched NHS patient controls. This evidence, combined with data from researchers at the Universities of Glasgow and London, suggests that the rise in hepatitis cases is unlikely to be linked to prior COVID-19 infection.
According to Dr. Meera Chand, Director of Clinical and Emerging Infections, “untangling the cause of the increase in childhood hepatitis cases observed in 2022 is complex,” and “multiple strands of the investigation point to the possibility that several different factors have combined to cause severe illness in some children.”
It’s important to remember that hepatitis in children is extremely rare, and new cases associated with this outbreak have now declined. UKHSA continues to work with academic and international partners to understand why this cluster occurred and any future risks.