5 ms·

I am hearing from friends and family in Brasil that the Brasilian variant is more severe among younger victims than the original COVID version. There is an incr

I am hearing from friends and family in Brasil that the Brasilian variant is more severe among younger victims than the original COVID version. There is an increase of deaths among twenty-year-olds as a result.

paulryanrogers 6y ago
All the more reason to stop all strains as soon as possible. If more contagious strains can be knocked below the sustainability threshold then they'll die out too.
- irq11 6y ago
  It is not possible to stop all strains. SARS-CoV2 has multiple zoonotic reservoirs, transmits easily, and persists in the population via asymptomatic infection. We have eradicated one human virus in all of history, and it took a highly effective vaccine and a hundred years. The long tail is very long.
  - hu3 6y ago
    Curious, what virus we eradicated?
    - celrod 6y ago
      Smallpox.
    - anoncake 6y ago
      Smallpox. Except for some samples in secure laboratories.
    - dillondoyle 6y ago
      Smallpox. I think we're close on polio?
      - oblio 6y ago
        We're getting there but it's super hard to do it in remote areas and conflict regions. https://www.gatesnotes.com/health/in-pakistan-victory-against-polio-is-in-the-hands-of-local-officials https://www.gatesnotes.com/health/in-pakistan-victory-agains...
    - Fomite 6y ago
      Smallpox and Rinderpest. Polio and Measles are doable, and at this point more logistical and political problems than biological ones.
      - irq11 6y ago
        The “logistical” and “political” problems being that they’re endemic in countries with major political and economic instability, where the locals have a bad tendency to kill the people doing the vaccinations. It isn’t a trivial problem. And oh yeah: Covid is in those countries now, too.
        Fomite 6y ago
        I never said they were trivial, and have argued exactly the opposite elsewhere. But it remains that they are logistical and political challenges, not biological ones.
  - lamontcg 6y ago
    It is still important to stop this particular strain and to achieve sufficient vaccination levels to achieve herd immunity. That immunity will likely be durable for many years (based on the somewhat recent study of HCoV-229E). That will force the virus to mutate to achieve true escape immunity (a strain, not a variant, which can reinfect everyone all over) which will likely come at a cost to fitness, since one or two mutations to spike isn't enough, and there will need to be a few tens of mutations to spike. That virus strain will not be as transmissible or virulent as what we are dealing with now, because it has had to make those costly "decisions". And this is important for people who for medical reasons cannot be vaccinate or who are at high risk even if they are vaccinated. They're much better off being infected by subsequent strains down the road than being infected with version 1.x of this virus. This is also what has been observed in the past with 1918 H1N1 which later evolved into seasonal influenza.
    - andy_ppp 6y ago
      “That virus strain will not be as transmissible or virulent as what we are dealing with now, because it has had to make those costly "decisions".” I’m not convinced you can absolutely guarantee these changes will make the virus less dangerous, we could be unlucky and it could become worse.
      - lamontcg 6y ago
        Right now that is what is happening, but as the title shows those variants don't achieve immune escape. The sum total of mutations necessary to achieve immune escape and overcome herd immunity is a lot more likely to come at a cost to overall fitness. Also I can't guarantee that West Ham United won't win the Premier League, but the safe money is all on Man City. Paper on the possibility of mild disease endemicity: https://science.sciencemag.org/content/371/6530/741 https://science.sciencemag.org/content/371/6530/741 AP coverage of that paper: https://apnews.com/article/common-cold-india-coronavirus-pandemic-latin-america-infectious-diseases-9ff4108bb925762655b6f6e23ffcf500 https://apnews.com/article/common-cold-india-coronavirus-pan...
      - bredren 6y ago
        I'm not convinced we can get an effective global, rolling vaccination program in place to set up effective population immunity. From what I can tell, almost all public discussion of the future of Covid is similar to a "happy path."
lamontcg 6y ago
The second wave of the 1918 pandemic was also more deadly to younger people. Various theories have been offered as to why, none of which are proven, including that it may have been observational errors or due to overcrowding conditions due to the war and viral dose. I wonder if it isn't due to the virus coming under pressure due to a large chunk of the population becoming immune, so evolution favors higher transmissibility. And the easy knob the virus has to increase transmissibility is to increase viral load, which has the side effect of increasing virulence/lethality. That is consistent with that fairly well studied mechanism of parasites/viruses, along with being consistent with what we're observing. At any rate considerations like that are why I'm not letting my guard down until I'm vaccinated and why it seems stupid to do so.
- ionwake 6y ago
  I dont believe virus ever increase in lethality as pressures increase, I thought the opposite happens, they naturally becomes less lethal to be able to spread more effectively. Also when you said " stupid to do so" what are you referring to? thx
  - lamontcg 6y ago
    That law doesn't exist. Mostly all the virus cares about is increased transmission, particularly with this virus with a long presymptomatic transmission period, it can evolve to become more lethal if that increases transmission. What would not be selected for would be enhanced virulence that shortens the presymptomatic transmission period. Short term the virus benefits by having higher viral loads and enhanced transmission and enhanced virulence, because it wants those higher viral loads in order to spread more. There's a limit because those higher viral loads are eventually what cause people to feel sick and stay home instead of attend superspreading events, so there's an optimum that its trying to find. As more and more people are immune though, there's probably selection pressure to make the most of whatever superspreading events occur at the expense of non-superspreading transmission. So more people get sick earlier and stay home, but the people who will try to push through a 101F fever the virus wants to have them infecting 100 people instead of 50. Long term the virus is going to evolve to become less lethal though because eventually we're going to hit herd immunity at the point where it can't evolve along the same fitness function to spread epidemically. At that point it needs to make many more mutations to all its epitopes that might be recognized by antibodies and T-cell and achieve enough immune escape to raise its R0 above 1.0 again. There's mutations which slide up and down the existing fitness curve (and some lucky mutations that might make the curve even better) but then there's mutations which are costly which are necessary due to the need for stealth and immune escape. Two different things. Also we have the example of the 1918 pandemic where the later waves were more virulent and lethal than the first wave (but much later it evolved to become seasonal influenza). Got much worse, then got better.

paulryanrogers 6y ago

All the more reason to stop all strains as soon as possible. If more contagious strains can be knocked below the sustainability threshold then they'll die out too.

irq11 6y ago
It is not possible to stop all strains. SARS-CoV2 has multiple zoonotic reservoirs, transmits easily, and persists in the population via asymptomatic infection. We have eradicated one human virus in all of history, and it took a highly effective vaccine and a hundred years. The long tail is very long.
- hu3 6y ago
  Curious, what virus we eradicated?
  - celrod 6y ago
    Smallpox.
  - anoncake 6y ago
    Smallpox. Except for some samples in secure laboratories.
  - dillondoyle 6y ago
    Smallpox. I think we're close on polio?
    - oblio 6y ago
      We're getting there but it's super hard to do it in remote areas and conflict regions. https://www.gatesnotes.com/health/in-pakistan-victory-against-polio-is-in-the-hands-of-local-officials https://www.gatesnotes.com/health/in-pakistan-victory-agains...
  - Fomite 6y ago
    Smallpox and Rinderpest. Polio and Measles are doable, and at this point more logistical and political problems than biological ones.
    - irq11 6y ago
      The “logistical” and “political” problems being that they’re endemic in countries with major political and economic instability, where the locals have a bad tendency to kill the people doing the vaccinations. It isn’t a trivial problem. And oh yeah: Covid is in those countries now, too.
      - Fomite 6y ago
        I never said they were trivial, and have argued exactly the opposite elsewhere. But it remains that they are logistical and political challenges, not biological ones.
- lamontcg 6y ago
  It is still important to stop this particular strain and to achieve sufficient vaccination levels to achieve herd immunity. That immunity will likely be durable for many years (based on the somewhat recent study of HCoV-229E). That will force the virus to mutate to achieve true escape immunity (a strain, not a variant, which can reinfect everyone all over) which will likely come at a cost to fitness, since one or two mutations to spike isn't enough, and there will need to be a few tens of mutations to spike. That virus strain will not be as transmissible or virulent as what we are dealing with now, because it has had to make those costly "decisions". And this is important for people who for medical reasons cannot be vaccinate or who are at high risk even if they are vaccinated. They're much better off being infected by subsequent strains down the road than being infected with version 1.x of this virus. This is also what has been observed in the past with 1918 H1N1 which later evolved into seasonal influenza.
  - andy_ppp 6y ago
    “That virus strain will not be as transmissible or virulent as what we are dealing with now, because it has had to make those costly "decisions".” I’m not convinced you can absolutely guarantee these changes will make the virus less dangerous, we could be unlucky and it could become worse.
    - lamontcg 6y ago
      Right now that is what is happening, but as the title shows those variants don't achieve immune escape. The sum total of mutations necessary to achieve immune escape and overcome herd immunity is a lot more likely to come at a cost to overall fitness. Also I can't guarantee that West Ham United won't win the Premier League, but the safe money is all on Man City. Paper on the possibility of mild disease endemicity: https://science.sciencemag.org/content/371/6530/741 https://science.sciencemag.org/content/371/6530/741 AP coverage of that paper: https://apnews.com/article/common-cold-india-coronavirus-pandemic-latin-america-infectious-diseases-9ff4108bb925762655b6f6e23ffcf500 https://apnews.com/article/common-cold-india-coronavirus-pan...
    - bredren 6y ago
      I'm not convinced we can get an effective global, rolling vaccination program in place to set up effective population immunity. From what I can tell, almost all public discussion of the future of Covid is similar to a "happy path."

lamontcg 6y ago

The second wave of the 1918 pandemic was also more deadly to younger people. Various theories have been offered as to why, none of which are proven, including that it may have been observational errors or due to overcrowding conditions due to the war and viral dose. I wonder if it isn't due to the virus coming under pressure due to a large chunk of the population becoming immune, so evolution favors higher transmissibility. And the easy knob the virus has to increase transmissibility is to increase viral load, which has the side effect of increasing virulence/lethality. That is consistent with that fairly well studied mechanism of parasites/viruses, along with being consistent with what we're observing. At any rate considerations like that are why I'm not letting my guard down until I'm vaccinated and why it seems stupid to do so.

ionwake 6y ago
I dont believe virus ever increase in lethality as pressures increase, I thought the opposite happens, they naturally becomes less lethal to be able to spread more effectively. Also when you said " stupid to do so" what are you referring to? thx
- lamontcg 6y ago
  That law doesn't exist. Mostly all the virus cares about is increased transmission, particularly with this virus with a long presymptomatic transmission period, it can evolve to become more lethal if that increases transmission. What would not be selected for would be enhanced virulence that shortens the presymptomatic transmission period. Short term the virus benefits by having higher viral loads and enhanced transmission and enhanced virulence, because it wants those higher viral loads in order to spread more. There's a limit because those higher viral loads are eventually what cause people to feel sick and stay home instead of attend superspreading events, so there's an optimum that its trying to find. As more and more people are immune though, there's probably selection pressure to make the most of whatever superspreading events occur at the expense of non-superspreading transmission. So more people get sick earlier and stay home, but the people who will try to push through a 101F fever the virus wants to have them infecting 100 people instead of 50. Long term the virus is going to evolve to become less lethal though because eventually we're going to hit herd immunity at the point where it can't evolve along the same fitness function to spread epidemically. At that point it needs to make many more mutations to all its epitopes that might be recognized by antibodies and T-cell and achieve enough immune escape to raise its R0 above 1.0 again. There's mutations which slide up and down the existing fitness curve (and some lucky mutations that might make the curve even better) but then there's mutations which are costly which are necessary due to the need for stealth and immune escape. Two different things. Also we have the example of the 1918 pandemic where the later waves were more virulent and lethal than the first wave (but much later it evolved to become seasonal influenza). Got much worse, then got better.