4 ms·

A virus that is extremely deadly, extremely contagious, and has an extremely long incubation period is quite unlikely, if not impossible. As far as I know this

A virus that is extremely deadly, extremely contagious, and has an extremely long incubation period is quite unlikely, if not impossible. As far as I know this is a typical "pick two" triangle.

objektif 7y ago
How so? Say can there be a strain of rabies that can be transmitted through air?
- projektfu 7y ago
  Virulence tends to be associated with a short incubation period. If it goes too long, then the immune system has time to respond. Rabies is a weird case in that it has low virulence but high lethality.
LolWolf 7y ago
Why? I agree that in the paper that Altman is referring to [0] H5N1 did appear to decrease in lethality after becoming airborne. The paper does not mention its incubation period. Do you have references for why a combination of these is not possible (or even unlikely)? I feel that it is quite possible to achieve by using only passage between animals (artificial or otherwise). —— [0] Table 1 of https://science.sciencemag.org/content/336/6088/1534/tab-pdf https://science.sciencemag.org/content/336/6088/1534/tab-pdf
- maxerickson 7y ago
  Infectiousness and incubation period tend to be in tension with each other, many routes for virus shedding are symptoms (runny nose, cough, etc). An extremely high death rate also does a better job of motivating responses, which while it isn't directly biological, has a significant impact on transmission. I'm not so sure we really understand the full possibility space of infectious diseases though.
  - LolWolf 7y ago
    > Infectiousness and incubation period tend to be in tension with each other, many routes for virus shedding are symptoms (runny nose, cough, etc). Yeah, I agree, but I think this is somewhat orthogonal to my point—gain-of-function[0] studies seem to indicate that artificial passage is potentially selective enough to make this possible, even though these things are usually negatively correlated. > An extremely high death rate also does a better job of motivating responses, which while it isn't directly biological, has a significant impact on transmission. Absolutely. This was also likely why we saw such a huge and immediate response to SARS, which seemed roughly as (if not more) contagious than SARS-nCov-2, but had a CFR of around 10%. SK was also much less well-equipped to handle it then than it would be today (likely due to that exact reason). > I'm not so sure we really understand the full possibility space of infectious diseases though. Agreed, and this is mostly my worry. --- [0] For an even more terrifying gain-of-function study on H7N9, with higher virulence and mortality than the H5N1 study, the reference is: https://www.nature.com/articles/nature12392 https://www.nature.com/articles/nature12392 In this case, the virus was also able to be transmitted from ferret to ferret and appeared to have very high concentration in the lungs of ferrets (much more so than H5N1 which was scary enough), which are the usual model for transmission and replication in humans.
elwell 7y ago
What about a virus that spreads to everyone before it triggered by some secondary catalyst virus?
blackrock 7y ago
This is an interesting triangle. Deadly, Contagious, or Incubation. Pick 2. This COVID-19 is contagious, and has a long incubation. The deadly part might be during secondary reinfection, or where it wears down your body’s defenses, that other diseases begins to ravage you. So, this virus might actually be the perfect combination of all 3.
deleted 7y ago
[deleted]
zshrdlu 7y ago
You forgot HIV.

A virus that is extremely deadly, extremely contagious, and has an extremely long incubation period is quite unlikely, if not impossible. As far as I know this is a typical "pick two" triangle.

objektif 7y ago

How so? Say can there be a strain of rabies that can be transmitted through air?

projektfu 7y ago
Virulence tends to be associated with a short incubation period. If it goes too long, then the immune system has time to respond. Rabies is a weird case in that it has low virulence but high lethality.

LolWolf 7y ago

Why? I agree that in the paper that Altman is referring to [0] H5N1 did appear to decrease in lethality after becoming airborne. The paper does not mention its incubation period. Do you have references for why a combination of these is not possible (or even unlikely)? I feel that it is quite possible to achieve by using only passage between animals (artificial or otherwise). —— [0] Table 1 of https://science.sciencemag.org/content/336/6088/1534/tab-pdf https://science.sciencemag.org/content/336/6088/1534/tab-pdf

maxerickson 7y ago
Infectiousness and incubation period tend to be in tension with each other, many routes for virus shedding are symptoms (runny nose, cough, etc). An extremely high death rate also does a better job of motivating responses, which while it isn't directly biological, has a significant impact on transmission. I'm not so sure we really understand the full possibility space of infectious diseases though.
- LolWolf 7y ago
  > Infectiousness and incubation period tend to be in tension with each other, many routes for virus shedding are symptoms (runny nose, cough, etc). Yeah, I agree, but I think this is somewhat orthogonal to my point—gain-of-function[0] studies seem to indicate that artificial passage is potentially selective enough to make this possible, even though these things are usually negatively correlated. > An extremely high death rate also does a better job of motivating responses, which while it isn't directly biological, has a significant impact on transmission. Absolutely. This was also likely why we saw such a huge and immediate response to SARS, which seemed roughly as (if not more) contagious than SARS-nCov-2, but had a CFR of around 10%. SK was also much less well-equipped to handle it then than it would be today (likely due to that exact reason). > I'm not so sure we really understand the full possibility space of infectious diseases though. Agreed, and this is mostly my worry. --- [0] For an even more terrifying gain-of-function study on H7N9, with higher virulence and mortality than the H5N1 study, the reference is: https://www.nature.com/articles/nature12392 https://www.nature.com/articles/nature12392 In this case, the virus was also able to be transmitted from ferret to ferret and appeared to have very high concentration in the lungs of ferrets (much more so than H5N1 which was scary enough), which are the usual model for transmission and replication in humans.

elwell 7y ago

What about a virus that spreads to everyone before it triggered by some secondary catalyst virus?

blackrock 7y ago

This is an interesting triangle. Deadly, Contagious, or Incubation. Pick 2. This COVID-19 is contagious, and has a long incubation. The deadly part might be during secondary reinfection, or where it wears down your body’s defenses, that other diseases begins to ravage you. So, this virus might actually be the perfect combination of all 3.

deleted 7y ago

[deleted]

zshrdlu 7y ago

You forgot HIV.