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Comment by baxtr | Hacker News Reader

> The biggest worry is a mutating virus that brings wave upon wave of attacks, each deadlier than the other.

From all that I've read and heard from virologist this is highly unlikely to happen. The way I understand it is that once a virus has jumped from animals to humans its virulence and danger will decrease continuously. A very simple explanation goes like this: the virus most lethal in the beginning because the human immune system is "naive" regarding that specific virus because it has not been exposed to it. For example, Prof. Drosten said in one of his podcasts that he could imagine you'd get Covid a second time after 2-3 years. But then it will be very mild, like a any normal cold.

So the biggest worries shouldn't be mutations of the SARS-2 virus but the next deadly bug crossing the animal-human barrier, e.g. a new influence virus breed in live stock somewhere.

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We also put pressure on viruses to make them less deadly.

Dead people don't spread the disease. And less symptomatic strains of the virus are likely to go unnoticed and therefore spread more rapidly.

I've seen some epidemiologist say that SARS-CoV-2 is expected to turn less severe and become endemic, causing common colds like the other 4 coronaviruses.

> Dead people don't spread the disease.

It seems that you can catch Coronavirus from people who died with it.

https://www.google.com/amp/s/www.livescience.com/amp/covid-1...

With the likes of Ebola, cultural practices such as washing the dead pose a significant risk of transmission.

https://www.nhs.uk/conditions/ebola/ https://www.nationalgeographic.com/news/2015/01/150130-ebola...

> It seems that you can catch Coronavirus from people who died with it.

It's more the "they don't go to the grocery store" thing.

Right. It's not in the virus's best interests to kill its host. In fact, our bodies are full of pathogens we've not only learned to live peaceably with, we need them to survive. And ancient viruses are part our DNA.

This mechanism was observed with, I believe, viruses like Marburg or Ebola, that tend(ed) to kill within hours or (few) days.

Covid-19 really does a pretty good job in this regard already: being infectious before symptoms begin, and taking weeks to either kill or resolve.

Very little would be gained, relatively, from the sort of changes Ebola & Marburg went through.

We also need to consider how people react to being infected with Covid-19: With the disease being universally known, what are the chances of a typical patient infecting additional people if you add another week at the back end of their infection? Chances are, they are in isolation from the second week on. Any contacts they keep having (with family, housemates, or medical personnel, say) will either be infected by week 3, or proven to be rather skilful at avoiding infection.

Hmmm, aren't we actually helping the deadly strains by putting a lot of effort in keeping those people alive? Those who usually would be dead, can actually survive nowadays, and that virus could somehow spread further?

Yeah maybe, but that's a pretty bleak point of view. "Sorry, you need to die so that this deadly variety can't continue to spread." I think we'd all rather give a fighting chance to anyone needing it using the best tools available.

Consider Smallpox. Smallpox ravaged humanity for thousands of years. Infected probably a billion people or more and you ended up with two subtypes. 90% of the infections were the more deadly type.

Explain how the virus could spread after they had recovered, a necessary step for which is their immune system clearing the virus.

This all depends on so many factors and there are still so many things that we don't know that I'm skeptical of people claiming they know how unlikely it is to happen. What is the degree of confidence of those virologists on their predictions?, what does highly unlikely mean in probabilities?. If you can share your sources I'd be happy to read them

From my understanding. A decrease of the virulence is the most likely outcome, however it's also possible (just not as likely) that a future strain could be both more deadly and have R0 > 1 (with R0 obviously depending of how we behave). We probably will not have a worse wave in the future but we should think about how to prepare for it.

It's not that there's a specific, quantified prediction for why it won't happen. There are countless endemic viruses in widespread circulation, including multiple other coronaviruses - they generally don't evolve to become more deadly, and there's no specific reason to believe this virus would.

> they generally don't evolve to become more deadly

That's a very important point and one that makes me agree with you in that it'll probably won't happen. This is because in most cases a virus reduces its R0 when its deadliness increases.

What I'm trying to point out is that "unlikely" is not impossible and since the stakes are high we should at least think seriously how likely the other possibility is.

For example we could think that for a virus like SARS-CoV-2 with asymptomatic contagion it's possible to think that a more deadly strain could maintain an R0 above 1 (because people pass it before becoming very ill). I talked more about this in https://news.ycombinator.com/item?id=23025899 to which I received a very thoughtful answer.

Again that does not mean that it will happen just that it could, and I believe we should encourage an informed discussion about this possibility

I'm not an epidemiologist by any stretch of the imagination but I would think for a virus with a long incubation time and asymptomatic spreading the R0 would be similar between the infected dying and simply recovering and their immune system eliminating the virus, other than the reduction in total population.

That's exactly the point I was trying to make

we live in the phase of the epidemic where alarmist news flourish

just as with any evolutionary process when the environment rewards a kind of behavior that behavior will become preponderant.

in this case even though it is far more likely that the virus would become less dangerous that idea gets less exposure, people will more likely read the scarier news.

> The way I understand it is that once a virus has jumped from animals to humans its virulence and danger will decrease continuously.

This is no truer than the quote about "each deadliner than the other". In fact many virii mutate continuously, c.f. the flu shot you need to get every year because there are always new strains.

It seems currently that SARS-CoV-2 is not doing this. But the science is still new and we just don't know.

We are observing mutations, and there’s a number of preprints out there describing mutations along the spike protein. I’m not sure which of the 100 vaccine candidates would continue to work if that were the case, but perhaps it will become like the flu where we need a different vaccine per strain and that sometimes the vaccine only provides partial protection

Covid-19 is mutating and they are using mutations to track how it spreads. That is why they think that US strain cme from Europe.

However, it is mutating slowly.

> That is why they think that US strain cme from Europe.

From what I've heard, NY stain seems to have come from Europe. I've not seen anything about the CA and WA strains.

I'll confess I've not had any antiviral shot for decades D:

Deadliness is a selection pressure, but if another selection pressure outweighs it and causes more deadliness as a side effect, it could still evolve to be more deadly. We can say that happening has some things going against it, but can't say for sure that it won't.

I raised my eyebrow as well when I read that. What I've read is that deadlier viruses tend to not spread as efficiently because it kills the host. So there is a pressure on the viruses to create symptoms that help spread the virus without killing the host.

COVID isn’t equal opportunity. Hopefully we will understand why certain people are critically ill or killed by the disease while others are not.

I know three people who have had it and since recovered. One wasn’t bad enough to seek help until day 12, one was sick with weakness and respiratory symptoms after 5-7 days of exposure, and the other was hospitalized within 48 hours of exposure.

None had the typical underlying conditions yakked about by commentators.

That may be what happens most of the time, but not always

https://upload.wikimedia.org/wikipedia/commons/9/9a/1918_spa...

It's possible it may not get deadlier over the long-term, but it is an RNA virus which means it's quite likely to continuously mutate (RNA is less stable than DNA). There is preliminary evidence of significant spike protein mutations when it went from China to Europe: https://www.biorxiv.org/content/10.1101/2020.04.29.069054v1

This may mean that it continues to plague humanity seasonally as do Influenza, Rhinovirus, etc., and it may also make a universal vaccine less likely.

Makes sense. I wonder how it compares to the flu. Each year/season we get new strains of it, which kill thousands of people and for which we are constantly developing new vaccines. It seems like the flu is a lot less contagious and deadly than covid, but who knows how long we've been dealing with it and it doesn't seem like it will go away anytime soon.

Totally. Happened with HIV right?

Yes... in monkeys.

Just need to give it a few million years or so.

Note that smallpox was much less deadly to Europeans than Native Americans.

Because people got variations of the disease (like cowpox)

More likely because selective pressure in Europe over the years meant that those who had any even partial immunity survived and passed that on, while in north America that pressure was missing.

Why is that more likely?

Small pox either was around, or something like it that jumped to humans

What about when it jumps from a lab to humans?

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