Acute hepatitis outbreak swells to nearly 900 cases; global data shows ‘mixed picture’



Easterbrook P. WHO & EASL media briefing on childhood acute hepatitis cases. Presented at: International Liver Congress; June 22-26, 2022; London (hybrid meeting).

The researchers report no relevant financial disclosures.

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LONDON – An outbreak of acute, severe hepatitis of unknown etiology in children has grown to 894 cases in 33 countries, according to data presented at a media briefing at the International Liver Congress.

“As of June 20, we have now reported 894 probable cases in 33 countries in five WHO regions,” Philippa Easterbrook, MD, senior scientist with the Global HIV, Hepatitis and STI programs at WHO headquarters in Geneva told attendees. “Since the last WHO public announcement on May 27, this is an additional 244 cases in a span of about a month. However, it is important to remember that this includes both new cases and retrospectively identified cases.”

Easterbrook noted that more than half of these cases (n = 449) come from the European region, with the UK alone accounting for 262 cases – nearly 30% of the global total. The second highest reporting region is America with 368 cases; as in the UK, the United States is home to a disproportionate number of cases, at 290, or 35% of the global total.

“Together, the United States and the United Kingdom account for 65% of the total number of cases worldwide,” she said. “The majority of cases – 75% – involve children under the age of five. Forty-four children have had liver transplants and 18 deaths have been reported. Fortunately, both European and US data do appear to be on a downward trajectory in terms of new case reports, which is a positive development.”

Philippa Easterbrook

Early in the study, adenovirus and past or current COVID-19 infection were the prime suspects “and still are,” Easterbrook noted, noting that these viruses are likely independent or collaborative causes leading to hepatitis.

“Adenovirus remains the most commonly detected of all viral infections with a detection rate of around 53% across Europe and slightly higher in the UK, but that is not the case in all cases,” she said. “There seems to be a higher detection rate in the younger age groups and in those who develop severe disease, so maybe there is a severity relationship.”

As for the current COVID infection, detection rates in both Europe and the US are about 10%, which researchers expect, given the transmission rate in the general population around that time.

“Some of the emerging hypotheses are: [whether this outbreak] represents a post-COVID phenomenon,” she said. “Is this a variant of the rare but recognized multisystem inflammatory syndrome disorder in children? It often occurs 1 to 2 months after COVID-19 and causes widespread organ damage, but it is rare, and the cases of hepatitis that have been reported do not appear to to match those characteristics.”

Easterbrook noted, however, that early on, researchers were able to rule out COVID-19 vaccination as a possible contributor. “Most children [in these cases] had not been vaccinated, especially the younger age groups, in accordance with the vaccination policy in force at the time,” she said. “The clear message is that 85% had not been vaccinated, so that cause was ruled out.”

For Easterbrook, the steady growth in the number of cases and an as-yet-unknown etiology have emphasized the importance of capturing consistent data from multiple countries.

“We’re seeing a somewhat mixed picture globally, with two countries reporting the most cases in high numbers,” she said. “We see differences in age distribution; we see some differences in the rate of adenovirus detection and COVID-19. It’s a mixed picture and we really need good quality data collected from other countries in a standardized way.”

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