As health authorities around the world race to understand the cause of a mysterious hepatitis outbreak in children, evidence of a link to Covid-19 is growing.
About 450 cases have now been reported in more than 25 countries worldwide, while almost a dozen children have died, according to the European Centre for Disease Prevention and Control (ECDE).
Five children have lost their lives to unexplained hepatitis in Indonesia, five in the US and one in Palestine, while in the UK, 11 children have required liver transplants.
In its update, the ECDE said the aetiology and pathogenetic mechanisms are still under investigation, but new research has thrown the spotlight on Covid.
Two studies have followed the chain reaction of the virus, highlighting that it may pave the way for hepatitis, while others suspect pandemic health measures have left children more vulnerable to illness.
A severe and unexplained killer
Hepatitis, an inflammation of the liver, is usually caused by a viral infection from hepatitis viruses A, B, C, D or E, but experts say those typical causes have not been detected in recent cases.
At the top of the suspects list is adenovirus, a large family of common viruses that typically cause mild cold and flu like illnesses.
It is commonly spread by close personal contact, respiratory droplets and surfaces, and is known to cause respiratory symptoms, conjunctivitis and digestive disorders.
Health authorities are continuing to investigate the potential role of SARS-CoV-2, the virus that causes Covid.
“The leading hypotheses remain those which involve an adenovirus,” Professor Phillipa Easterbrook from the World Health Organisation’s global hepatitis program said.
“But I think with also an important consideration about the role of Covid as well, either as a co-infection or as a past infection.”
Research points to the super antigen of the Coronavirus
Hundreds of cases of acute hepatitis in children of unknown causes may be associated with the super antigen of coronavirus, according to a new study published in The Lancet Gastroenterology and Hepatology.
Researchers believe the cases were probably the result of a Covid infection, followed by an adenovirus infection after the emergence of a viral reservoir in the intestinal tract.
The report suggests it is possible the affected children, many of whom were too young to receive the Covid vaccine, may have had mild or asymptomatic Covid infections that went unnoticed.
While in the US, a recent case study published in the Journal of Pediatric Gastroenterology and Nutrition analysed a three-year-old girl who developed acute liver failure a few weeks after recovering from a mild Covid infection.
While the author said it was impossible to prove that Covid directly caused the liver disease, they said it is possible that the virus triggered an abnormal immune response that attacked her liver.
The Covid-co factor
UK researchers suggest that public health measures and lockdowns as a result of the pandemic have reduced exposure to viruses, leaving children more susceptible to adenovirus infections.
A further theory is that a ‘cofactor’, such as prior or existing infection with another virus like Covid, may cause a more severe reaction or abnormal immune response to adenovirus infection.
While currently only a small number of children with hepatitis have tested positive for Covid, of those tested in the UK, around 18 per cent returned a positive PCR test for Covid.
Researchers are now looking to find out what proportion of hepatitis patients have antibodies to SARS-CoV-2 and have been infected in the past.
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