While many have recovered, 11 needed urgent liver transplants. The majority of cases were in the United Kingdom, but now children are affected in the United States, Japan and Israel. One child has died, according to the World Health Organization – he did not say in which country – while U.S. health officials are investigating the death of another young man with suspected hepatitis. Hepatitis is the term used to describe inflammation in the liver, an organ that helps filter toxins from the body. It often causes only mild flu-like symptoms, but can also lead to more serious problems such as jaundice, swelling of the feet, ankles and feet, and blood in the stool and vomit. According to the United Kingdom Health Insurance Agency (UKHSA), all 145 cases of the latest hepatitis outbreak in the UK so far have been in people under the age of 16, with the vast majority being under the age of five. (File image) In its most extreme form, hepatitis can cause liver failure and patients may need a transplant to survive. The five viruses that cause it are known as hepatitis A, B, C, D and E. They are transmitted in different ways, depending on the virus, including contaminated blood, feces or badly cooked meat. Hepatitis can also be caused by toxins, such as those found in industrial chemicals, drugs and, more commonly, alcohol. Although it is not clear what causes these cases of hepatitis in children, and theories revolve around blaming everything from lockdowns to hidden viruses, we have asked scientists the relevant questions about this mysterious outbreak. What do we know so far about the affected children? The pop-ups do not match the typical patient profile. According to the United Kingdom Health Insurance Agency (UKHSA), all 145 cases detected in the last outbreak in the UK so far have been in people under the age of 16, with the vast majority under the age of five. Experts say this is surprising, as young children are usually not severely affected by the common causes of hepatitis. “Hepatitis viruses usually flush children out without causing too much damage,” says Professor Will Irving, a virologist at the University of Nottingham. “Adults are much more likely to get seriously ill. “And, of course, we can rule out alcohol as a factor.” Research conducted by the UKHSA also found no toxins in the blood or urine of children, ruling out theories about food contamination. Scientists say that, every year, hospitals actually see a small number of children suffering from severe hepatitis for no apparent reason. But these figures are vague compared to this recent rise. Are there any theories for the cause of all this? Scientists have discovered a common feature – more than three-quarters of cases are positive for a pathogen called adenovirus 41F. Adenoviruses are a group of about 80 viruses that usually infect the upper respiratory tract, leading to coughing, runny nose or pneumonia. They can sometimes infect the gut and lead to severe stomach pain, but the adenoviruses that reach the liver are almost unheard of. There does not seem to be a clear link between the cases. With the exception of two children in Wales, none of the patients, who are scattered in the UK, appear to have been in contact with each other or to have a personal relationship. Scientists say this shows that if an adenovirus is the cause, it is not transmitted from person to person. But they also say that, given how many patients appear to carry the pathogen, it is very likely that adenovirus 41F is somehow linked to the outbreak. “Adenovirus infection is really the only striking consequence in these cases that we can find so far,” said Professor Alasdair Munro, a pediatric infectious disease specialist at Southampton University Hospital. Could there be a link to previous Covid infections? Experts believe that Covid may also be linked to the phenomenon, but the exact nature of this link is still unclear. According to the UKHSA, 16 percent of children admitted to hospital with severe hepatitis were positive for Covid. But scientists say this is to be expected and is not necessarily related to inflammation of the liver. “If you have 100 children, then you will inevitably see a similar level of Covid infection,” says Professor Simon Taylor-Robinson, a liver specialist at Imperial College London. “This does not mean that it is the cause of hepatitis.” However, experts believe that a previous infection with Covid in combination with an adenovirus infection may trigger inflammation of the liver. Hepatitis can also be triggered by an autoimmune response – when the body’s immune system attacks healthy cells. This can often happen after a viral infection. While the UKHSA is still assessing how many children have previously been infected with Covid, scientists say it is very likely that almost everyone already has the virus at some point. Experts say a previous Covid infection could cause children’s immune systems to react differently to an adenovirus infection. “There may be some viral interaction with Covid and the adenovirus, which causes the immune system to respond in unexpected ways,” says Professor Munro. Is this a negative effect of lockdown isolation? It is true that social contact was severely curtailed during the Covid lockdown and, as a result, fewer viruses were transmitted. According to the UKHSA, reported cases of colds, flu and other common viruses dropped to almost zero in the first year of the pandemic. As a result, many babies are just now infected with viruses they would normally have contracted as newborns. But experts are divided over whether this is the cause here. “The lack of immunity to adenoviruses could mean that these infections lead to serious responses that we have never seen before,” said Professor Alastair Sutcliffe, a pediatrician at University College London. Others point to UKHSA data showing that while the transmission of many diseases was disrupted by the lockdown, adenovirus levels remained relatively stable throughout. “Theories that this is related to lockdown are purely speculative and very ill-defined,” said Professor Adam Finn, a pediatrician at the University of Bristol. Could the Covid vaccine have caused this? Experts say one thing is for sure – hepatitis cases are not linked to the Covid vaccine because none of the children who were treated had been vaccinated. This is because the majority are under five years old and therefore do not qualify for the Covid vaccine. In addition, of the Covid vaccines used in the UK, only Oxford-AstraZeneca uses adenovirus and many studies confirm that the pathogen in the vaccine is inactive, meaning that it cannot infect the body. Scientists say a more interesting theory is that the cases could have been caused by a virus they could not recognize. “There has long been a belief that there is a sixth hepatitis virus out there that causes these occasional unexplained serious cases in children,” says Professor Irving. “It is possible that, along with all the other illnesses that have erupted since we left the lockdown, this mysterious hepatitis has also increased. “Fortunately, we now have the genetic testing technology to detect this kind of disease, something we did not do a few years ago, so if that is the case, research in the coming weeks and months will find it.” So how much should we worry about this? Doctors say the chances of a child getting sick with the condition are slim. The UK is currently recording an average of one to two new cases per day and there is no indication that this number is increasing. Of the more than 100 children admitted to hospital in England with the condition, more than 50 have fully recovered, while just under 40 are being monitored in hospital. At the time of writing, 11 children in the UK have needed a liver transplant and none have died. “While it must be a horrific experience for any parent to see their child need a transplant, fortunately this only happens in a very small number of patients,” says Professor Irving.
