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Comment by sylware | Hacker News Reader

I don't understand why a slightly delayed exposure to some "common" viruses can almost destroy the liver of young children.

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Immunity and level of exposure are very tightly coupled. Children would ordinarily be exposed to a variety of viruses from birth. Most encounters with a virus happen at very low viral load (e.g. total number of virus particles you're exposed to). During lockdowns, the diversity of viruses that children were exposed to dramatically dropped. Newborns and young children were now only exposed to viruses that were already in their household. Hence, young children have likely developed immunity to a smaller pool of viruses.

Once lockdowns ended, they were then exposed to many viruses their immune systems had never seen. Some of these exposures would be at low viral load, giving them a chance to build immunity. Some of these exposures would be at high viral load, overwhelming their immune system and leading to illness.

It’s not as if kids coming out of lockdown are suddenly exposed to a disproportionately higher number / load of virii than if they were exposed at a younger age.

What do you mean, exactly? Yes, the situation seems to be that kids coming out of lockdown are suddenly exposed to a disproportionately higher number of new virii in a short time than if they had been gradually exposed to them over the previous two years.

I mean that the viral loads they'd be exposed to in year 3 (post lockdown) would be the same as the loads they would have been exposed to in year 1 if there had been no lockdown.

A person's immune system is different in year 1 than in year 3 (and in basically all other variations of N and N+2).

It appears that children not getting sick in the first few years of their lives paired with some mutations that aren't uncommon can cause the immune system to stay too weak. This is one of the leading theories why so many children get Leukemia. This is a pretty serious scientific study on the phenomenon:

https://www.nature.com/articles/s41568-018-0015-6

It’s similar to chickenpox in that it’s much safer to be exposed younger, but in this case it’s more pronounced

Most kids nowadays (hopefully) get the chickenpox vaccine and never have to suffer from it or shingles as adults.

Not in the UK, where the chickenpox vaccine isn't part of the vaccines given by the NHS.

Wow. I did not peg the NHS as an anti-vax organization

Not anti-vax, they don't want to spend money on something like that. There's a reason the USA spends lots of money on healthcare and the UK does not (though it's obviously relative on a country scale). It's not through magic, it's through spending less money. Spending less money in a healthcare system demands sacrifices, some quite severe.

They have a detailed explanation here https://www.nhs.uk/conditions/vaccinations/chickenpox-vaccin...

Not sure if irony/sarcasm will lead to a more productive discussion.

FYI chicken pox is not part of the routine vaccine schedule (in the UK) to protect unvaccinated adults:

"There's a worry that introducing chickenpox vaccination for all children could increase the risk of chickenpox and shingles in adults."

https://www.nhs.uk/conditions/vaccinations/chickenpox-vaccin...

>Not sure if irony/sarcasm will lead to a more productive discussion.

Productive discussion, perhaps not. Productive thought, I believe so. If it penetrates the reflexive defensive barrier that so many have around polarizing topics, that’s a win

I see your point, and if I understand you correctly, it is evidenced by the success of the Twitter/Tik-Tok/etc. recommendation algorithms.

I'm just not sure we need productive thoughts more that productive discussions, given that we will face more collective 'resource allocation problems' over the next decades.

That’s quite regrettable. It’s a safe vaccine that totally eliminates chickenpox and adult shingles. It’s a standard childhood vaccine in the US and has been for some time.

As someone who’s suffered though fairly severe shingles twice, I’m a fan of this being eliminated.

Interestingly the reason the NHS has for this is vaccination can result in giving adults shingles (I simplify: https://patient.info/news-and-features/should-your-child-hav... explains).

As a result shingles seems rarer in the UK (no data, from personal experience, never heard of anyone getting it).

That doesn’t make any sense though. Make the kids suffer chicken pox AND shingles as adults do adults don’t get shingles as often? Anyone who contracts chickenpox as a child is able to get shingles as an adult. Inversely, anyone who gets the chickenpox vaccine as a child is unable to get shingles as an adult.

Kids that are vaccinated for chickenpox can’t get shingles as adults. That’s a really poor way to optimize.

Adults can also get shingles vaccines, which exist, and are safe, but are only given generally to elderly and very immunocompromised.

Shingles is not common in the US, I’ve had it twice due to an extremely stressful job: I’m perhaps an outlier as I got it in two places at once (1% of people get this) and one of which was in my eye, almost causing permanent blindness. This would never have happened at all had the vaccine existed when I was a child and I was vaccinated.

Yes. Very young children have a different type of immune system. They are simultaneously highly resilient to some viruses that can kill adults, while being highly susceptible to other infections that adults can handle.

The thymus comes to mind as a factor. As we age, the thymus shrinks. Children have a larger thymus which aids in combating viruses. Perhaps if these children had been exposed earlier, no hepatitis would have occurred.

I'd like to see if these cases would have occurred anyway in the preceding years. It may be that cases that were normally(hypothetical numbers for example purposes only) 1/1000 before lockdown went to 1/10,000 during, and after, went to 1/100. Taking the average over a 10 year period, this may be totally expected and not too concerning. If this is true my first point is incorrect.

It means if those children missed exposure to those common viruses, in a less than 2 years window, their liver will be destroyed???

Wow, wow, wow, this would be VERY nasty, and it would mean that we must be SURE those children get exposed in the right time window????

I can't find a reference right now, but delayed exposure is thought to be one reason why polio turned into a severe disease. Polio has been endemic in humans for generations, but it started causing severe disease in the late 1800's/early 1900's.

Previously, infants were exposed to polio, but increasing hygiene meant that exposure would be delayed.

Again, I can't find a reference for this now, so I'm probably getting details wrong.

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