Explained | The mysterious hepatitis outbreak among children around the world

The World Health Organisation has rejected the hypothesis linking the hepatitis outbreak to side effects of the Covid-19 vaccine.

April 29, 2022 02:01 pm | Updated 08:19 pm IST

Vaccination of infants in Dharavi, Mumbai. Photo used for representation only.

Vaccination of infants in Dharavi, Mumbai. Photo used for representation only. | Photo Credit: Aadesh Chouhari

The story so far: More than ten countries across the globe, including the U.S., the U.K., Japan, Spain, Israel, and France have reported an uptick in the number of cases of acute hepatitis observed in young children.

Distribution of cases of acute severe hepatitis of unknown origin by country, as of 23 April 2022.

Distribution of cases of acute severe hepatitis of unknown origin by country, as of 23 April 2022.

The cause of the disease is unknown but health experts are of the view that it is being driven by adenovirus. The number of cases globally now stands close to 200 and is increasing at a concerning rate. Over 100 of these cases have been reported from the U.K.

What is the outbreak and when was it first observed?

The earliest known cases of hepatitis infection of unknown origin were reported in the U.S. in October 2021, the country’s Centres for Disease Control and Protection (CDC) informed. A total of nine children, between ages one and six years, were admitted to a children’s hospital in Alabama, U.S. between October 2021 and February 2022 with “significant liver injury”. These hepatitis patients were previously healthy and not infected by the SARS-CoV-2 virus that causes Covid-19. Some of these children were reported to have acute liver failure, and all of them tested positive for adenovirus.

The CDC issued a nationwide alert on April 21, 2022 to notify healthcare workers of the hepatitis and adenovirus outbreak. Other U.S. States like Delaware, North Carolina, and Illinois have also reported suspected or confirmed cases of severe liver disorder in children. The Wisconsin Department of Health Services has reported that one of four cases under investigation has resulted in the death of the patient.

The U.K has observed an alarming increase in the number of pediatric hepatitis cases. An investigation by the U.K. Heath Security Agency (UKHSA) has revealed that the usual viruses (types A to E) that cause hepatitis have not been found in the children affected by the liver infection.

Most cases in the U.K. have been observed in children under five years of age. Symptoms usually begin with diarrhoea and nausea followed by the onset of jaundice. UKHSA also noted that 16% of the cases admitted between January and April 2022 tested positive for coronavirus but cases across the U.K. were on the rise during the time period.

Ten children in the U.K. have received liver transplant so far.

The Netherlands has also reported an increase in community circulation of adenovirus infection.

Japan and Canada are the latest countries to report cases of hepatitis with unknown origin in children.

Anders Koch, the chief physician at Denmark’s Statens Serum Institut, has said that the disease only poses a small risk. “Even if it is a specific cause and not sporadic cases, the risk of the individual child being affected by this rare form of hepatitis is still incredibly small,” Mr. Koch was quoted as saying.

Health agencies around the world are investigating the possible causes of the hepatitis outbreak and the links among various clusters, if any. The UKHSA is investigating whether reduced exposure to adenovirus due to physical distancing during the Covid-19 pandemic is the cause behind more severe symptoms in young children. Other plausible causes being looked into are an undiscovered coinfection or toxin, or a new strain of adenovirus.

Timeline of the hepatitis outbreak

Timeline of the hepatitis outbreak

What is adenovirus?

Adenoviruses are common viruses that are responsible for a wide range of diseases. It is spread through close personal contact, through the air by coughing or sneezing, or through fomites. The viruses generally cause respiratory illnesses, gastroenteritis, conjunctivitis, or cystitis. In rare cases, it can also lead to neurological diseases.

In children, adenovirus type 41 is known to cause acute gastroenteritis.

Some of the children in the Alabama cluster were infected with adenovirus type 41, and its symptoms include diarrhoea, vomiting, and fever. The type 41 virus is not known to cause hepatitis in healthy children, but some immunocompromised children with the disease have been observed to carry the type 41 infection.

The CDC is currently investigating a link between hepatitis in children and adenovirus infection.

What are the symptoms of hepatitis?

Hepatitis is essentially an inflammation of the liver. The five main strains of the virus are types A, B, C, D, and E.

Common symptoms of hepatitis include fever, fatigue, itchy skin, loss of appetite, nausea, vomiting, abdominal pain, dark urine, light-coloured stools, joint pain, muscle pain, and jaundice.

Can the hepatitis infection be linked to Covid-19 vaccine?

According to the UKHSA, none of the currently confirmed cases in under ten-year-olds is known to have been vaccinated against Covid-19. The World Health Organisation has also rejected the hypothesis linking the infection to side effects of the Covid-19 vaccine.

What are the hepatitis vaccinations available in India?

In India, children are provided with vaccination against hepatitis B under the Universal Immunisation Programme. It is given to infants as early as possible and within 24 hours of birth. Following doses are given at 6, 10, and 14 weeks in the form of pentavalent vaccine that also fights against diptheria, tetanus, pertussis, and Haemophilus influenza type B infection. Vaccine for hepatitis B also provides safeguard against hepatitis D infection.

Vaccination against hepatitis A is also available.

Watch | Inside the world's biggest vaccine production hub

(With inputs from agencies)

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