5 ms·

I expect this to be the case since decreased severity is associated with higher virus reproduction. The main question becomes second order effects.

by adolph 5y ago

loceng 5y ago
Yup, tradeoffs forced to select towards survival.
- janmo 5y ago
  Being more severe and deadly is not necessarily a propagation disadvantage. Because if you sick you stay at home and don't go out. If you are very sick, you need to go to the doctor, or the hospital. This can create more spread.
- jazzyjackson 5y ago
  wow, suddenly I feel like the film "Venom" was trying to teach me this, it's no good for the virus if it keeps killing its hosts, really its mutating itself while searching for a host that can coexist with it (as I understand it, much of our DNA is incorporated from viruses, but I don't understand it very well :)
  - deleted 5y ago
    [deleted]
  - mcbits 5y ago
    It already coexisted with a host: bats. If we're going to anthropromorphize the virus, maybe it's searching for a way to kill off one of the biggest predators of its preferred host.
- PeterisP 5y ago
  For people, the difference between 2% and 0.2% mortality is huge, but for the virus (and the evolutionary pressures on it), the difference between 98% and 99.8% chance of continuing to spread is insignificant; any minor changes in the rate of spread far outweigh that. The evolutionary pressure towards survival of the host matter only for diseases with very high lethality.
- throwhauser 5y ago
  > Yup, tradeoffs forced to select towards survival. Viruses don't have a plan, or intent. It's not impossible for a virus to screw itself over and kill off all its hosts, or one species of hosts. https://www.wired.com/2008/11/yes-disease-can/ https://www.wired.com/2008/11/yes-disease-can/
deleted 5y ago
[deleted]
orra 5y ago
We definitely shouldn't oversimplify. Delta was simultaneously more infectious and more deadly than the original variant. Virus mutations can be better for us, and they can be worse. This article https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7095397/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7095397/ paints a sensibly nuanced picture.
- easytiger 5y ago
  > Delta was simultaneously more infectious and more deadly than the original variant. That's not my understanding
  - gitfan86 5y ago
    We don't know for sure, because a lot of people with and without symptoms got tested regularly.
  - orra 5y ago
    It's well known it's more infectious, and widely suspected to be more deadly. See both https://www.nationalgeographic.com/science/article/why-is-delta-more-infectious-and-deadly-new-research-holds-answers https://www.nationalgeographic.com/science/article/why-is-de... and https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-variant.html https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-var...
    - syshum 5y ago
      The problem with these studies is the mild symptom cases may never even be reported as cases, I know alot of people that had covid symptoms but never got tested, and would never get tested unless it got to the point where they needed medical care. So if you just had a "pretty bad" flu and sat at home you likely never got tested, and thus would never show up in these studies Hell I know a couple people that were told by local medical center to not even bother with the test, they just assumed it was covid, was told to self isolate and monitor.
      - 5y ago
flerovium 5y ago
This is not necessarily the case for a virus with such a long period of asymptomatic transmission. There is very little selective pressure for the virus to become less deadly; in fact, higher viron count is positively associated with both transmissibility and mortality.
- elevaet 5y ago
  Exactly. People overlook this fact constantly. There is no selection pressure for a virus like this to become more or less deadly. Just pressure to become more transmissible within our mixture of vaxxed, unvaxed, and some natural immunity.
  - hackinthebochs 5y ago
    Increasing the window of contagious spread is likely to be inversely correlated with deadliness.
    - flerovium 5y ago
      Transmissibility is highest before symptoms appear. This the distinct characteristic of COVID-19 that separates it from most viruses and has enabled it to spread rapidly on a global scale.
      - hackinthebochs 5y ago
        I don't see how that negates my point. If the virus can mutate to have a longer transmissibility window, it implies that it will also be less deadly. The period when symptoms start is the period where your immune response is ramped up. Delaying or reducing the immune response implies longer transmission window and less severe illness.
        Lhiw 5y ago
        It doesn't imply that at all. There could be a number of ways the virus delays early immune response while still creating more problems later at a different scale.
monopoledance 5y ago
Not inherently. Good counter example is the delta variant, which was worse in every aspect.
somewhereoutth 5y ago
Not true I'm afraid. Of course, if a virus killed you before you had a chance to pass it on then yes - but most viruses (including SARS-CoV-2) kill you slowly enough to have plenty of opportunity to propagate, there is no selection pressure to be less deadly. To my knowledge, we have no evidence that any human virus has evolved to become less virulent (please furnish examples if I'm wrong!). Unfortunately this common myth, that contagiousness is inversely correlated with lethality, has been used by those who would wish to downplay this public health disaster for whatever reason.
- semerda 5y ago
  Replication-incompetent adenoviral vectors? Lex Fridman had a virologist on his podcast talking about the mutations done to the adenovirus to make it safe for the delivery of the s-protein (used in viral vector J&J + AstraZ vax). Maybe I misunderstood that?
  - somewhereoutth 5y ago
    Engineered vs evolved. For sure you can take a virus and knock out the bad bits - but I believe we have no evidence this has occurred in the wild due to selection pressure.
    - semerda 5y ago
      I’m not talking about inactivation with formaldehyde. If they did that in the viral vector it would disable the delivery mechanism (adenovirus).
- janmo 5y ago
  I guess the Spanish flue probably did
- danenania 5y ago
  “To my knowledge, we have no evidence that any human virus has evolved to become less virulent (please furnish examples if I'm wrong!).” Isn’t this what happened with the influenza strain that caused the Spanish Flu pandemic?

I expect this to be the case since decreased severity is associated with higher virus reproduction. The main question becomes second order effects.

by adolph 5y ago

I expect this to be the case since decreased severity is associated with higher virus reproduction. The main question becomes second order effects.

loceng 5y ago

Yup, tradeoffs forced to select towards survival.

janmo 5y ago
Being more severe and deadly is not necessarily a propagation disadvantage. Because if you sick you stay at home and don't go out. If you are very sick, you need to go to the doctor, or the hospital. This can create more spread.
jazzyjackson 5y ago
wow, suddenly I feel like the film "Venom" was trying to teach me this, it's no good for the virus if it keeps killing its hosts, really its mutating itself while searching for a host that can coexist with it (as I understand it, much of our DNA is incorporated from viruses, but I don't understand it very well :)
- deleted 5y ago
  [deleted]
- mcbits 5y ago
  It already coexisted with a host: bats. If we're going to anthropromorphize the virus, maybe it's searching for a way to kill off one of the biggest predators of its preferred host.
PeterisP 5y ago
For people, the difference between 2% and 0.2% mortality is huge, but for the virus (and the evolutionary pressures on it), the difference between 98% and 99.8% chance of continuing to spread is insignificant; any minor changes in the rate of spread far outweigh that. The evolutionary pressure towards survival of the host matter only for diseases with very high lethality.
throwhauser 5y ago
> Yup, tradeoffs forced to select towards survival. Viruses don't have a plan, or intent. It's not impossible for a virus to screw itself over and kill off all its hosts, or one species of hosts. https://www.wired.com/2008/11/yes-disease-can/ https://www.wired.com/2008/11/yes-disease-can/

deleted 5y ago

[deleted]

orra 5y ago

We definitely shouldn't oversimplify. Delta was simultaneously more infectious and more deadly than the original variant. Virus mutations can be better for us, and they can be worse. This article https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7095397/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7095397/ paints a sensibly nuanced picture.

easytiger 5y ago
> Delta was simultaneously more infectious and more deadly than the original variant. That's not my understanding
- gitfan86 5y ago
  We don't know for sure, because a lot of people with and without symptoms got tested regularly.
- orra 5y ago
  It's well known it's more infectious, and widely suspected to be more deadly. See both https://www.nationalgeographic.com/science/article/why-is-delta-more-infectious-and-deadly-new-research-holds-answers https://www.nationalgeographic.com/science/article/why-is-de... and https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-variant.html https://www.cdc.gov/coronavirus/2019-ncov/variants/delta-var...
  - syshum 5y ago
    The problem with these studies is the mild symptom cases may never even be reported as cases, I know alot of people that had covid symptoms but never got tested, and would never get tested unless it got to the point where they needed medical care. So if you just had a "pretty bad" flu and sat at home you likely never got tested, and thus would never show up in these studies Hell I know a couple people that were told by local medical center to not even bother with the test, they just assumed it was covid, was told to self isolate and monitor.
    - 5y ago

flerovium 5y ago

This is not necessarily the case for a virus with such a long period of asymptomatic transmission. There is very little selective pressure for the virus to become less deadly; in fact, higher viron count is positively associated with both transmissibility and mortality.

elevaet 5y ago
Exactly. People overlook this fact constantly. There is no selection pressure for a virus like this to become more or less deadly. Just pressure to become more transmissible within our mixture of vaxxed, unvaxed, and some natural immunity.
- hackinthebochs 5y ago
  Increasing the window of contagious spread is likely to be inversely correlated with deadliness.
  - flerovium 5y ago
    Transmissibility is highest before symptoms appear. This the distinct characteristic of COVID-19 that separates it from most viruses and has enabled it to spread rapidly on a global scale.
    - hackinthebochs 5y ago
      I don't see how that negates my point. If the virus can mutate to have a longer transmissibility window, it implies that it will also be less deadly. The period when symptoms start is the period where your immune response is ramped up. Delaying or reducing the immune response implies longer transmission window and less severe illness.
      - Lhiw 5y ago
        It doesn't imply that at all. There could be a number of ways the virus delays early immune response while still creating more problems later at a different scale.

monopoledance 5y ago

Not inherently. Good counter example is the delta variant, which was worse in every aspect.

somewhereoutth 5y ago

Not true I'm afraid. Of course, if a virus killed you before you had a chance to pass it on then yes - but most viruses (including SARS-CoV-2) kill you slowly enough to have plenty of opportunity to propagate, there is no selection pressure to be less deadly. To my knowledge, we have no evidence that any human virus has evolved to become less virulent (please furnish examples if I'm wrong!). Unfortunately this common myth, that contagiousness is inversely correlated with lethality, has been used by those who would wish to downplay this public health disaster for whatever reason.

semerda 5y ago
Replication-incompetent adenoviral vectors? Lex Fridman had a virologist on his podcast talking about the mutations done to the adenovirus to make it safe for the delivery of the s-protein (used in viral vector J&J + AstraZ vax). Maybe I misunderstood that?
- somewhereoutth 5y ago
  Engineered vs evolved. For sure you can take a virus and knock out the bad bits - but I believe we have no evidence this has occurred in the wild due to selection pressure.
  - semerda 5y ago
    I’m not talking about inactivation with formaldehyde. If they did that in the viral vector it would disable the delivery mechanism (adenovirus).
janmo 5y ago
I guess the Spanish flue probably did
danenania 5y ago
“To my knowledge, we have no evidence that any human virus has evolved to become less virulent (please furnish examples if I'm wrong!).” Isn’t this what happened with the influenza strain that caused the Spanish Flu pandemic?