Cases of severe acute hepatitis of unknown origin in children are not related to COVID-19 vaccines; an adenovirus infection is the most likely hypothesis so far


Cases of acute hepatitis in children are related to vaccines against COVID-19


Incorrect: Most children affected by hepatitis did not receive the COVID-19 vaccine. The adenovirus that has been associated with most cases is different from the adenoviral vectors used in some COVID-19 vaccines.
Incorrect: Although adenovirus infection is one of the hypothetical causes of these cases, the actual cause of hepatitis cases in children remains unconfirmed.


Since October 2021, almost 200 cases of severe acute hepatitis of unknown origin have been detected in young children in several European countries and in the US. One of the most striking features of the disease is its unusual severity, with 10% of cases requiring liver transplantation. . The main hypothesis so far is that an adenovirus infection is causing or contributing to the disease, but health authorities continue to investigate other possible causes, including exposure to a toxic agent or infection with a new pathogen.

FULL CLAIM: “Children are contracting hepatitis. It is being caused by an adenovirus. J&J had an adenovirus vector. It couldn’t possibly be related.”


On April 15, 2022, the WHO issued a multicountry alert on an increase in cases of severe acute illness hepatitis (inflammation of the liver) of unknown origin in previously healthy children. The seriousness of the cases is striking because they are rare in children. The first reported cases involved ten children aged 11 months to five years in the UK, with the first case dating from January 2022. As of April 2022, the United States Y 11 European countries had reported at least 169 cases in children from one month to 16 years and at least one death. Almost 70% (114) of the cases reported so far are in the UK

However, social media posts hinting at a link between these unusual cases of hepatitis and the COVID-19 vaccine followed shortly after these reports were published (examples here Y here). For example, this tweet in particular, he linked the cases of hepatitis to the Johnson and Johnson COVID-19 vaccine by stating that the hepatitis was “caused by an adenovirus” and “J&J had an adenovirus vector.” Other mail on Instagram who shared the tweet claimed that “all health care providers [sic] duty to assume that it is related”.

However, this assumption is incorrect for several reasons that we explain below. In summary, these reasons are: First, the majority of affected children did not receive the COVID-19 vaccine. Second, although an adenovirus infection is a possible hypothesis, it has not been confirmed as the cause of the disease. Finally, the adenovirus associated with many of the cases of hepatitis in children is different from those used in adenovirus-based COVID-19 vaccines.

Current evidence indicates that cases of hepatitis in children are not related to vaccination against COVID-19

These cases of pediatric hepatitis are worrisome due to the severity of the symptoms and their unknown origin.

Although the cause of the disease is unknown, latest reports of the United Kingdom Health Security Agency (UKHSA) state that there is “no link” with COVID-19 vaccines. The first known cases five children were hospitalized in the US state of Alabama in October 2021, about a month before the unroll of COVID-19 vaccines in children. The UKHSA also explained that none of the confirmed cases in the UK as of April 25, 2022, which are almost 70% of all cases, had received a COVID-19 vaccine.

In fact, the cases of hepatitis occurred predominantly in children under the age of five, which means that they are not eligible for vaccination with any of the available COVID-19 vaccines. This includes the Johnson and Johnson COVID-19 vaccine, which is only authorized for people over 18 years old. The only COVID-19 vaccines that children can receive are the pediatric vaccines from Pfizer and BioNTech In the USA; in the European Union, both Pfizer-BioNTech and the modern vaccine are authorized for children. None of these vaccines use an adenoviral vector; both are based on mRNA technology.

Laboratory tests excluded infection with the hepatitis viruses A, B, C, D and E, ruling out one of the most common causes of hepatitis In children. Less commonly, liver inflammation can also be due to other causes, such as genetic disorders, Autoimmune diseasesor exposure to toxins. However, all affected children were apparently healthy before diagnosis. UK health authorities also reported no evidence from any common exposure to a potentially toxic agent through medications, food or water, travel, contact with animals, and parental occupation.

Hepatitis cases also you don’t look like be related to SARS-CoV-2 infection. Only 16% of cases reported in the UK had an ongoing SARS-CoV-2 infection at the time of testing. Also, severe hepatitis is not common in children with COVID-19.[1]which makes this hypothesis unlikely.

However, more laboratory tests to other possible viral infections revealed that about 75% of cases tested positive for adenovirus type F41 infection[2]. there are at least 49 different types of adenoviruses that can infect humans, and the F41 type is different from those used to develop adenoviral vaccines against COVID-19. The Johnson and Johnson COVID-19 Vaccine, which is the only licensed adenoviral vaccine in the US, uses a modified version of adenovirus 26 that causes the common cold in humans. The Oxford-AstraZeneca COVID-19 vaccine authorized in the European Union uses a modified version of the ChAdOx1 adenoviral vector that causes the common cold in chimpanzees.

Furthermore, the adenoviral vectors used in these COVID-19 vaccines are modified versions that are replication-incompetent. That means they cannot multiply and cause an infection in those vaccinated or spread to other people.

The above evidence shows that COVID-19 vaccines are not the cause of these cases of hepatitis in children, since the vast majority of children did not receive the vaccine and the adenovirus vector used in some COVID-19 vaccines does not have relation to the found in affected children.

Adenovirus infection has not yet been confirmed as a cause of hepatitis in children; the cause remains unknown

Although an adenoviral infection is one of the main hypotheses to explain cases of hepatitis in children, several questions raise questions about whether it is the definitive cause. One of them is that it cannot explain the 25% of cases that tested negative for this virus.

More importantly, the hypothesis of an adenoviral infection would not explain the severity of the symptoms. common symptoms of this new form of hepatitis in children include gastrointestinal problems, vomiting, and yellowing of the skin and eyes (jaundice). All cases had elevated blood levels of liver enzymes known as transaminases, indicating liver cell damage. About 10% of the cases required liver transplantation, which “in this age group [is] extremely rare” explained UKHSA Chief Medical Adviser Susan Hopkins for the BBC.

Adenovirus infections are quite common in children, but typically cause mild respiratory and gastrointestinal symptoms[3]. While adenoviruses can occasionally cause hepatitis, this is extremely rare and is mostly limited to immunosuppressed people.[4,5].

The UKHSA has proposed two main Work hypothesis that could cause an adenovirus to behave differently than it normally does. The first is that this is due to a new strain of adenovirus causing more severe disease. The second is that an additional factor is at play that increases children’s susceptibility to infection, such as reduced exposure to infections during the pandemic, previous infection or co-infection with another infectious agent, or simultaneous exposure to an unknown toxin. .

Alternatively, the UKHSA proposes other possible scenarios, including (from most to least likely) infection with a new pathogen, exposure to a toxic agent, or infection with a new, unidentified variant of SARS-CoV-2.


Claims that this new form of hepatitis in children is caused directly or indirectly by COVID-19 vaccines are not supported by evidence. Most of the affected children were under the age of five and therefore could not receive the COVID-19 vaccine. The adenovirus identified in many of the cases is also different from those used in adenovirus-based COVID-19 vaccines; adenovirus vectors used in vaccines have also been modified to be non-infectious. Although an adenovirus infection is one of the hypothetical causes of these cases of hepatitis, the cause remains unconfirmed. Public health authorities are still investigating other possible causes.


East Twitter thread for muge cevik, professor of infectious diseases and medical virology at the UK’s University of St Andrews, summarizes the state of UK research. He reported on a presentation by UKHSA’s Director of Clinical and Emerging Infections, Meera Chand, at a special session at the European Congress of Clinical Microbiology and Infectious Diseases on April 25, 2022.


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