The significant increase in cases of hepatitis in young children - are the covid vaccines responsible?

Possibly...

Over the past few months there has been a worrying level of serious cases of hepatitis in children under the age of 5. The levels of this condition are still very low (just over 100 cases in the UK), but it is very serious, with eight children in the UK requiring liver transplants.

At the moment the cause of these cases is not known, but the one thing that is constantly repeated is that the vaccines aren’t responsible — and this is ‘clearly the case’ as the children concerned hadn’t been vaccinated.

However, one factor that keeps being repeated is that there seems to be a link with adenovirus infection. This has led to speculation that these cases are due to a high incidence of adenovirus infection due to decreased social interactions during lockdowns and thus lower levels of natural immunity specifically in those young enough to not have had a prior adenovirus infection.

It is worth pointing out that adenovirus infections are rather common — it is one of the viruses that cause ‘the common cold’. Furthermore, hepatitis is known to be a possible complication of adenovirus infection in the young (ie, those without natural immunity), although it is a very rare complication usually seen in the immunocompromised.

So if the children affected by this condition haven’t been vaccinated why do I suggest that there might be a link with the vaccines?

The ‘red-flag’ is that some of the covid-19 vaccines used an adenovirus vector to deliver the code for the spike protein into cells, to promote the body’s immune system to create a level of immunity to covid-19. The vaccines in question are the Janssen vaccine (Johnson & Johnson in the USA), the Astrazeneca vaccine and Russia’s Sputnik vaccine.

These adenovirus vector vaccines are genetically modified to make it impossible for them to replicate in the body, which means that there is no risk of a vaccinated person infecting others. This genetic modification involves the removal of a complete section of the DNA of the virus, so it isn’t possible for a simple mutation to result in the virus regaining the ability to replicate.

However, it is possible that the adenovirus vector could regain the ability to replicate, primarily via two potential mechanisms (eg, see Baldo et al, Condit et al):

• The virus could regain the ability to replicate while being manufactured. This a known risk for viral vector vaccines, and as a result, it is recommended that each batch of vaccine is tested to identify if this has occurred. I’m not aware of any reports of this having occurred with the Astrazeneca or Janssen vaccines, although I note that we’re reliant on the pharma companies reporting openly with respect to this outcome. However, there were reports in 2021 of the virus in some batches of the Sputnik vaccine having regained some ability to replicate. This risk resulted in Brazil rejecting the Sputnik vaccine.

• The virus could regain the ability to replicate in the vaccinated. One method that causes viruses to change over time is recombination — the process where two strains of a virus combine to form a hybrid virus with some characteristics of each of the ‘parent’ viruses. For this to occur an individual (actually, a cell within an individual) needs to be infected with two variants of a similar virus at the same time. As adenovirus infections are common in humans, it is likely that a number of individuals were vaccinated while currently infected with a natural adenovirus — if the two viruses recombined it is possible that a hybrid virus could be formed with the ability to replicate provided by the natural infection, and the encoding for the spike protein from the viral vector. The risk of this occurring with the Astrazeneca vaccine is low (as they used a chimpanzee adenovirus), but both the Janssen and Sputnik vaccines used human adenoviruses and thus the risk must be considered to be tangible.

But has this occurred? As noted in the studies referenced earlier, there is a low risk of it occurring — however, you have to multiply the low probability of occurrence by the number of vaccinations given, which number in the hundreds of millions.

I’m not suggesting that this has definitely occurred — but it is a risk. If it has occurred it could be identified by genome sequencing of the specific adenovirus infections or even simply by testing whether the infected children have antibodies to covid’s S-protein but not its N-protein (this is a hallmark of those exposed to the covid vaccines).

What is surprising is that this doesn’t seem to have been done. Hopefully there’ll be clarification over the coming weeks.

Note that if it has occurred those most initially at risk will be young children, as the hybrid virus will probably have reduced infectiousness compared with endemic adenoviruses and most adults have sufficient cross-immunity from prior infections. The exception is if it has occurred with the Astrazeneca vaccine, as most humans don’t have any immunity to chimpanzee adenovirus (the exception being those vaccinated with the Astrazeneca vaccine). It is unclear whether there’d by any risk of a hybrid virus evolving to become more infectious to humans (I suppose we should hope that it wouldn’t).