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Comment by billiam | Hacker News Reader

I don't know what the point of such conjecture is. Of course we don't know how much immunity comes from infection, and it is quite clear from the spread of delta that we are nowhere near herd immunity in the developed world, even in places like Israel. I had a coronavirus called a cold last year; does that mean I'm immune this year? Unlikely in the long term with COVID. The entire concept of herd immunity may be a mirage: if the (rare) breakthrough infections in vaccinated people like me spread just as much virus as unvaccinated, then there may be a huge potential for incubating new strains among the mRNA-ed that may elude all our current vaccines. And unlike a lot of viruses, the latest variants may be just as lethal as the earlier ones. Usually viruses become more transmissible and less lethal in response to rational behavior in their hosts--but humans are proving we're not rational.

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> Of course we don't know how much immunity comes from infection

Come on, this is silly. We haven't learned nothing over the last year. https://www.nih.gov/news-events/nih-research-matters/lasting...

This is true, however those studies are for the initial SARS-COV-2 strain and doesn't make any mention of the variants.

It's also worth noting that's a study of ~200 people. Given then times we're in it's an excellent sign and possible reason for cautious optimism and I'm sure a larger scale study is much harder to pull off in the midst of the pandemic.

That said, I have yet to see a study on the rate of reinfection of any of the variants against people who had already been infected with the initial strain, and how well that is survived, etc.

> Usually viruses become more transmissible and less lethal in response to rational behavior in their hosts--but humans are proving we're not rational.

I was under the impression viruses became less lethal because if they became more, they'd kill off their hosts and be less likely to spread.

There's a chance you get some super virus that becomes both more transmissible and lethal, but that is very rare (from what I can see).

It depends. It’s hard to model and even think about the selection pressures accurately. West Nile virus showed a marked increase in virulence in corvids recently as did rabbit hemorrhagic disease.

And let’s not forget about Mareks disease, where a non-sterilizing vaccine is thought to have contributed to a massive increase in virulence, killing nearly 100% of unvaccinated chickens now vs causing mild disease decades ago.

Does that not assume that you’re symptomatic at the same time you’re spreading the virus? With covid you appear to be able to spread before you know you have it. Given that, what force would cause the virus to be selected for less lethality?

With a different presentation of disease where symptoms and spread occur concurrently then there would be a pressure on the virus selecting for strains that arent so lethal a carrier has no chance to spread. In covid’s case, that pressure doesn’t exist as far as i can see?

> I was under the impression viruses became less lethal because if they became more, they'd kill off their hosts and be less likely to spread.

Only if the lethality is negatively impacting their fitness. If it can spread to another host quickly, who cares if the previous host dies. There's no selective pressure against it.

Which is why Delta is scary. Not just because of the higher viral load, but new strains could be more lethal and still not be selected against.

> I had a coronavirus called a cold last year; does that mean I'm immune this year?

There are supposedly over 200 different viruses that can cause the common cold (https://www.nih.gov/news-events/nih-research-matters/underst...). So it's quite possible for immunity to any individual strain to last a very long time and still get multiple colds per year.

> Usually viruses become more transmissible and less lethal in response to rational behavior in their hosts--but humans are proving we're not rational.

Our own "rationality" doesn't matter much, if a virus leaves you bed-ridden or dead, that makes it very hard for you spread it regardless of your choices. The fact that we have so many different viruses which essentially cause more or less the same "common cold" proves that there is very strong evolutionary pressure for a virus to behave this way.

You're missing the point because the media (and their pharmaceutical advertisers) have framed everything in terms of vaccination, as if the human immune system is incapable of surviving COVID and it's variants.

All viruses get less lethal as time goes on, not stronger, despite all the fear porn that has been indoctrinated into the public over the last year and a half.

Certain viruses maintained their lethality as time went on. Smallpox was very lethal throughout time. Influenza lethality ebbs throughout history. I don't think we can or should depend on less-lethal, common-cold-like symptoms from Covid-19 at any point.

Is there a reason we shouldn't expect it to behave like most coroanviruses?

There actually is. The evolutionary selection pressure on most coronaviruses exists throughout its infectious stage. So in order to be more infectious for longer the coronavirus would become less symptomatic and so less serious.

But with C19 we are aggressively isolating people with symptoms. This focuses evolutionary selection pressure on the initial infectious stage. In order to be more infectious the virus increases viral load and shedding, causing more serious symptoms; which would be an evolutionary disadvantage, except isolation renders this disadvantage moot.

Also natural immunity general focuses on the nucleus of the virus, vaccine immunity is to the spike. So this forces mutations in different proteins, which has different results.

Are you saying without lockdowns it would have turned in a regular cold by now?

Not lock-downs specifically. Testing and isolating, Maybe, but it would have cost many more lives.

SARS-CoV-2 does cause common cold like symptoms in the vast majority of cases, just like other coronaviruses. In particular it's quite similar to HCoV-OC43. The only reason those other endemic coronaviruses don't kill many people is that most of us get infected as children and build up some immunity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252012/

> All viruses get less lethal as time goes on, not stronger,

This isn't true. Given certain assumptions, it's true on average, but those assumptions don't apply in this case.

Agree.

For a specific example the Spanish Flu hit harder later on.

> All viruses get less lethal as time goes on

Smallpox.

Smallpox luckily was a very stable DNA virus with a low mutation rate so it became possible to eradicate it.

> All viruses get less lethal as time goes on, not stronger.

Wrong. It's generally the case, because a virus that keeps its host walking around will tend to infect more people than a virus that sends them straight to the morgue.

SARS-Cov-2 is unusual in that it's asymptomatic infectious period is really quite long. It's straight-to-morgue capabilities could become much more prevalent with hitting its infectivity too badly.

Here's the thing: even if the virus is less lethal, if it results in more hospitalizations, we are headed for lockdown again if hospital capacity starts getting threatened: all of the routine heart attack, stroke, laceration/crush emergencies we need to deal with routinely will be unable to find adequate care if anti-vaccine holdouts are storming the hospitals for ventilators, or even just inpatient observation. And if our politicians responsibly do lock down to head this off, they probably STILL won't understand how the power was in their own hands to stop it. Businesses will shutter again, kids will miss even more school, and the hospitality industry will again stumble because people refused to understand that even a small number of non lethal hospitalizations spread over the entire population is enough to overwhelm healthcare infrastructure.

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