Hacker News Reader

> Or is there a difference between SARS-CoV-2 and hookworms/common livestock bacterial infections that matters in this case?

One can be continuously infected and reinfected with parasites or bacterial. Viral infections like COVID either kill you or get cleared from your system, at which point for all practical purposes you are fairly immune for a while.

These are all so wildly different that its irresponsible & actively harmful to attempt drawing any parallels.

Assuming this is in good faith, the answer is it does apply evolutionary pressure on covid to develop a spike protein that can avoid the immune system.

Convalescent people do have a more diverse immune response, to other parts of the virus. And after a vaccine actually have even stronger responses still.

The immune response to covid and the spike protein in immunized people is very uniform and the antibodies we produce are very similar (although not identical.)

But the specificity of the spike targeting was chosen for a reason, it is VERY unlikely there is another spike protein that will work as well and entirely evade the immune system. Studies have been done and threatening spike mutations have been checked, and it doesn't seem like there are good alternatives.

> it does apply evolutionary pressure on covid to develop a spike protein that can avoid the immune system

The way you say this, it seems to imply some kind of intelligent mutation, is that true of viruses? I was under the impression that they would simply accidentally evolve around it as they reproduce themselves over and over. Thus if you limit their ability to reproduce, you'd limit their chances of mutating in ways that avoid the immune response.

Where as for bacteria, my understanding was that, while it similarly accidentally evolves around it, by abusing antibiotics, you kill the bacteria that isn't resistant, thus the resistant bacteria will proliferate in its place, and possibly eventually become the dominant strain. While if you'd left the body deal with the bacteria, this would not happen, and so you should only resort to antibiotics in cases where the person's immune system is losing the battle.

The immune system does not work that way. When you present an antigen to it, it trains a variety of antibodies to different sites on the antigen, and these antibodies are slightly different for every person.

It's as if instead of taking one antibiotic against a bacterial infection, you took many slightly different ones at the same time, and every treatment of antibiotics differed. Obviously, bacteria are much less likely to develop resistance that way.

Vaccine evasion can happen if the virus mutates so much it's almost unrecognizable (flu) or if the vaccine is too narrowly targeted and it presents not enough sites for the immune system, so a single mutation is enough for immunity.

The former apparently doesn't apply to Covid**, the latter basically never happens - the old dead/weakened methods avoided this by design, while the newer methods learnt to watch out for this and present enough of the virus.

* Mutations kept the spike. There were several mutations that changed it so there's a limited level of evasion from vaccine and natural immunity (Beta, Kappa), but these mutations apparently strongly hurt the ability to spread, so much that these variants seem to decline naturally before reaching epidemic status.

> Actually (and this might sound crazy, but I encourage you to think through it and respond), why not apply this logic to COVID-19 vaccines, as well?

I've never heard of a vaccine that causes viruses to seek resistance to it, that's one major difference. The vaccines don't actually attack the virus, they simply train your body's own immune system to recognize the virus, so that if you get infected, your body's own defenses can more quickly isolate the virus and attack it.

What I've heard happen more often in viruses, is that the more people get the virus and the more their body is slow to stop the virus from reproducing, the more likely the virus is to mutate.

So from my understanding, with viruses, it is the opposite, you want to make sure the virus doesn't get a chance to reproduce itself, because more reproduction = more chance of mutation. And vaccines help lower the reproduction amount of a virus by having people's immune system be able to stop it from doing so much more quickly than otherwise.

> why not use non-pharmaceutical means to try to control the virus (which would be equivalent to dog racetrack owners trying to keep their racetrack clean

You mean like for example by social distancing, wearing masks, disinfecting surfaces, improving air flow, and restricting activities that are high contagion spots?

Most countries are doing that already, while also hoping to get people vaccinated so that we can lower the virus' chances of reproducing and thus spreading to others as well as mutating.

> Or is there a difference between SARS-CoV-2 and hookworms/common livestock bacterial infections that matters in this case?

It is my understanding that a virus does not reproduce when it is on a surface or in the air, the way that bacteria and parasite can, a virus can only reproduce when inside of a living cell. So the virus will mutate if people have the virus in their body, and their immune system is not able to stop it from reproducing. Vaccines help teach the immune system how to best get rid of the virus in one's body so it doesn't get a lot of chances to reproduce. And measures like social distancing, face covering, surface cleaning, prevent the virus from getting into people's body in the first place, where they could reproduce and thus mutate.

I'm seeing some down-votes, but it's hard for me to know if it's just because of the overly political nature of the topic or if my understanding of viruses in this case is flawed? From my reading on the topics I believe it correct to the best of my abilities, but this is not my area of professional expertise, so I'd love to hear from people who might know more about it.

Why have an arms race with something other

> Actually (and this might sound crazy, but I encourage you to think through it and respond), why not apply this logic to COVID-19 vaccines, as well?

The COVID-19 vaccines train the immune system to attack the spike protein. A mutation that avoids this would successfully dodge the immune system… and not be able to latch onto and infect cells, because the same thing that makes the spike protein work (the shape(?) of the binding site(?)) is also the thing that makes the immune system attack it.

It's theoretically possible for a SARS-CoV-2 virus to be so mutated (SARS-CoV-3?) that the spike protein is radically different, but in a way that just so happens to also work. However, that's unlikely – the immune system also pays attention to other bits of a virus (even though the mRNA vaccine doesn't), and in the unlikely event this happened, the immune system would probably be able to kill the mutated version without problems.

But it could happen, if there are breeding populations of COVID-19 in people with weak / unprimed immune systems – for the same reason you need to take the full course of antibiotics, we need to get as many people as possible vaccinated.

---

The important thing isn't medication. Do a heat treatment of some agar that isn't quite hot enough, and the bacteria will become heat resistant. Anything that provides selection pressure (kills some, but not all, of the population) can trigger evolution in the direction of “thing is less good at killing”.

A single (mutant) heat-resistant bacterium will probably die in a 121°C pressurised steam environment, but might survive 5 minutes of an 80°C environment that most of its fellow bacteria die to. Then a substantial portion of the surviving bacteria twenty generations later (i.e. a million times more bacteria) would be heat-resistant descendants of this survivor, making the once-effective treatment much less effective.

Also: bacteria can share DNA between each other, so if one becomes resistant, it can share its resistance with other bacteria. Viruses can't do this; viruses are almost inert outside cells, and it's unlikely that two different viruses will infect the same cell at the same time. (It does happen, though, with influenza, because there's so much influenza and, more importantly, several strains of similar-enough versions for a recombination to be viable.)