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Comment by tus89 | Hacker News Reader

More interesting to know does it lead to a significant drop in transmission?

I don't mean to imply that this is your intention at all, but it's a false choice. Both questions are interesting; no need to set them up as if they were in tension with one another.

It actually can put them in tension. If the vaccine only stops symptoms it can remove the selective pressure to be less deadly and can actually cause the virus to evolve to be more deadly overall.

If this is the situation we are in, then it would make the most sense to only vaccinate the most vulnerable, and not vaccinate the bulk of the population in order to keep the virus selected for survival + transmissibility.

"...can actually cause the virus to evolve to be more deadly overall"

That is wildly speculative. Pathogens do not evolve inevitably towards maximum lethality.

> That is wildly speculative.

I'm not sure what more you should be asking for in a discussion about "what could happen"

Of course it is speculation. And it is based on what we know about other viruses at large and the our current best information about covid.

I meant less interesting as in all the studies/trials have already confirmed that the vaccines significantly reduce severe symptoms...the effect on transmission is still an open question from what I understand.

Yes, I'm also personally most interested in that question. (But will accept more data on any of these questions, since they're so societally important.)

Preliminary results look good

https://www.reuters.com/article/health-coronavirus-israel-va...

Yes, the preliminary numbers out of Israel appear to confirm this.

https://www.reuters.com/article/health-coronavirus-israel-va...

Why is that more interesting? Reducing severity is just as important as reducing transmission, if not more important.

If we could sufficiently reduce (or eliminate) severe cases and deaths, it wouldn't matter how contagious it was. Common colds are highly transmissible, but no one worries about them much since they very rarely cause severe illness.

Reducing severity is just as important as reducing transmission.

I know what you're driving at and it's all pretty interesting - but counterintuitively I think it's way more effective overall to reduce transmission than it is to reduce severity.

If you make the disease half as deadly, then pretty simply half as many people die. But if you make the disease half as transmissible, then the compound impact means that far fewer than half as many people die.

True. But if you make the disease not deadly at all, then no one dies, regardless of how transmissible it is.

Untill you visit a place with a significant un-vaccinated population.

This has happened with other diseases.

The problem is that if the vaccinated population carries the virus, then the risk of being infected increases for the unvaccinated population. It doesn't matter if the vaccine reduces the severity of the virus if you haven't received the vaccine.

On the other hand, if the vaccine reduces the transmissibility of the virus, then everybody collectively benefits from each additional vaccination.

Isn' that how you end up with a leaky vaccine? https://en.wikipedia.org/wiki/Marek%27s_disease

While it seems rare, it also seems like a much deadlier outcome.

Not everyone can be vaccinated for a plethora of reasons. This would do nothing for that cohort.

That is not the case - it is for that specific variant of the disease but diseases spread through the entire population have a huge area to mutate in and one of those mutations could be quite deadly.

One of the reason there's a lot of gas behind rolling this vaccine out quickly is that we want to avoid allowing the virus enough time to mutate up some different strains that this vaccine isn't effective in preparing us for since that makes the vaccine far less effective overall.

> If you make the disease half as deadly,

I think you undercut your own point for no reason.

Less deadly diseases get less reverence, leading to more risk taking. The percentage of people who die goes down, but the number of cases goes way up, resulting in potentially greater loss of life overall. Look at how cavalier we are about influenza, and then we set policy based on whether things are worse than the flu.

It's very important until universal vaccination is achieved.

Well obviously it would be great if they significantly reduce transmission as well. But even if they don't, vaccines could still effectively end the pandemic if they reduce severity enough.

It's stupid to imply that drastically reducing severity isn't a big win.

Only in that the effect on severe illness (reduction) has already been demonstrated through the studies/trials, this is not really news. Transmission effect is still being understood.

Fair enough when you put it that way :)

Probably.

https://www.reuters.com/article/health-coronavirus-israel-va...

Why is this more interesting exactly? If vaccines remove severe consequences of getting sick then why does it matter if the virus is still around?

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