Ask HN: Are Covid Vaccines “Leaky”? | Hacker News Reader

Ask HN: Are Covid Vaccines “Leaky”?

5 pointskypro5 comments

I've been reading a bit about Marek's disease this weekend. It's an interesting case where the vaccine for Marek's disease has inadvertently allowed highly virulent strains of Marek disease to propagate causing its fatally rate to reach 100% in unvaccinated birds.

https://en.wikipedia.org/wiki/Marek%27s_disease

My understanding is that COVID vaccines do limit spread, but as can be seen from forums like Reddit's "COVID19 positive" (https://www.reddit.com/r/COVID19positive/) many people who are fully vaccinated do still contract COVID and health officials have stated that it's possible to still spread COVID in these cases.

This seems to be a growing issue as more recent variants seem to have adapted to circumvent existing vaccines and we're seeing growing numbers of people now become infected despite being fully vaccinated. Of course, the argument is that if you're fully vaccinated then you're likely to have milder symptoms, but as with the vaccine for Marek's disease we can assume this would then enviably reduce selection pressure against highly virulent strains.

I'm really hoping someone can explain to me why this isn't a concern. Admittedly the person who made me aware of this is fairly conspiratorial, but so far I have no good argument against what they're suggesting could happen.

First, I'd check their source for saying that the number of cases in vaccinated people is growing. I mean, of course it is - 2 is more than 1, so whatever number we are at, it is growing... but is the actual percentage growing? Or is it just the expected rate?

Also, there is little in this world that is black and white. You cannot look at a pandemic and just flip a switch to go from "concerning" to "not a concern". Vaccination is better than not. There really isn't any argument against that. But that doesn't mean we just turned off the pandemic and nobody will ever get sick again. That simply is not how it works.

So could there be long-term consequences? Sure. Does that change what our actions should be today? No.

As far as arguing against such things... don't accept their premises. Check their data sources. Most of the poor arguments out there are based on bad data or myopic logic. Or both.

> First, I'd check their source for saying that the number of cases in vaccinated people is growing. I mean, of course it is - 2 is more than 1, so whatever number we are at, it is growing... but is the actual percentage growing? Or is it just the expected rate?

This wasn't a claim they made to be fair to them. This is just what I understand from what I've been reading about effectiveness of the vaccines in regards to the delta variant. I've read they're effective against it, but slightly less so and presumably selection pressure will continue this trend now vaccines are being deployed on mass.

> So could there be long-term consequences? Sure. Does that change what our actions should be today? No.

Does it not? To be clear, I'm not personally concerned about this in an anti-vax sense, but I am a little concerned we could enter a kind of arms race against evolution and end up creating something potentially worse down the line unless we're careful about how we deploy vaccines and combat COVID. You seem to be suggesting we should just look past these risks and hope for the best (please correct me if you feel I'm misrepresenting you), but surely if we're aware these risks exist we should be attempting to reduce the likelihood of them occurring?

> You seem to be suggesting we should just look past these risks and hope for the best.

Yep, you read that right. Maybe I am being too careless about my approach, but... think of it like a potential car wreck. If someone is stopped in front of me, I slam on the brakes, regardless of whether the guy behind me might rear-end me. We have to fix the problems in front of us, with the best knowledge and options we have available.

Certainly if we can also avoid negative consequences at the same time, yes, we should avoid them. No arguments there. But I'm not an expert in this field, so I trust the scientists who are experts and who are telling us this is our best move.

[Sorry for the late reply, but I hope it's useful for the OP:]

I agree. But it's interesting to look at the history of the polio vaccine. Oversimplifying, the first vaccine was injectable and "leaky"[1] (and a huge success), the second vaccine was oral and not leaky. So even if we get a leaky vaccine now, we can improve it or make another in five years. Anyway, the oral vaccine has other problems, so when a country has no cases for a long time, the country use only the injectable one. More details and accuracy: https://en.wikipedia.org/wiki/Polio_vaccine

[1] Is "leaky" the correct technical term?

The only thing I can add to this is that some agencies have at least been clear that even after vaccination, people should still be social distancing and wearing a mask. I realize that is far looser in the US, but here in Canada, it has not been loosened in this way.

With birds, you won't be masking them or keeping them at distances. So their ability to spread disease is significantly higher.

Our take on this up here at least is that you have to do everything to get these numbers down. We recognize that you can still catch and spread the virus even if you've been vaccinated. Apparently you'll get less ill if you are vaccinated and catch it, but you still have to avoid infecting people who have not yet been fully vaccinated - something birds don't have as much control over.

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