3 ms·

"So have death rates dropped because of improvements in treatments? Or is it because of the change in who's getting sick? " No, it's likely dropping because th

"So have death rates dropped because of improvements in treatments? Or is it because of the change in who's getting sick? " No, it's likely dropping because the virus is changing. There were several hundred variants of the virus by May (in the UK, most of which were found worldwide). It is a completely normal and expected event that a virus new to humans, will evolve to become less likely to either kill the host, or stir up a counter-response from the immune system, since variants that do either of those have a harder time spreading than variants that don't (or do them less). John Ioannidis (https://www.who.int/bulletin/online_first/BLT.20.265892.pdf https://www.who.int/bulletin/online_first/BLT.20.265892.pdf) has demonstrated that the virus' mortality rate is around 0.39% among those under 70. The study here is looking at the mortality rate among those hospitalized, which could be changing simply because those who get sick are more or less willing to go to the hospital, or for half a dozen other reasons that have nothing to do with either who's getting sick or how they are being treated.

HarryHirsch 6y ago
a virus new to humans, will evolve to become less likely to either kill the host Oh, come on, the pox had mortality > 30 %. Evolutionary pressure favours easy spreading.
- SiempreViernes 6y ago
  If you want to learn more about smallpox go to this url: https://ourworldindata.org/smallpox https://ourworldindata.org/smallpox
- rossdavidh 6y ago
  Sure, evolution pressure favors easy spreading, but if sick people stay home or go to the hospital, and non-sick people go out, then that pressure is to make the host sick less often. Early estimates for mortality in Wuhan were 3-5%. Later estimates kept dropping, and are now at 0.39%. Most viruses do not make the host sick, and the longer it's been in humans, the more likely it is that this is so. If the mortality rate is dropping (the article's assertion), but the WHO says none of the existing treatments has been shown to work, then the simplest explanation is that the virus has evolved in that direction. Given that the virus is very new in humans, there's nothing surprising about that.
  - HarryHirsch 6y ago
    Coronaviruses mutate quite slowly, this one has been around for less than a year, you would not expect to see much change in virulence over that timespan. Any lowering of mortality is best explained by more thorough testing.
    - rossdavidh 6y ago
      From https://www.sciencedaily.com/releases/2020/04/200409085644.htm https://www.sciencedaily.com/releases/2020/04/200409085644.h... "There are too many rapid mutations to neatly trace a COVID-19 family tree. We used a mathematical network algorithm to visualise all the plausible trees simultaneously," said geneticist Dr Peter Forster, lead author from the University of Cambridge. Also here: https://www.sciencedaily.com/releases/2020/05/200505190550.htm https://www.sciencedaily.com/releases/2020/05/200505190550.h... "They identified 198 mutations that appear to have independently occurred more than once, which may hold clues to how the virus is adapting..." It may "mutate quite slowly" compared to, say, influenza, but compared to anything else it is mutating quite a lot, in only a matter of months. Virus generations are pretty fast.
      - HarryHirsch 6y ago
        This report takes the exact opposite viewpoint: https://www.nature.com/articles/d41586-020-02544-6 https://www.nature.com/articles/d41586-020-02544-6 "A typical SARS-CoV-2 virus accumulates only two single-letter mutations per month in its genome."
        rossdavidh 6y ago
        Interesting article! But, from that very article: "Despite the virus’s sluggish mutation rate, researchers have catalogued more than 12,000 mutations in SARS-CoV-2 genomes." Now, that doesn't tell us that these mutations matter, but that's because we don't know which ones matter. But even a rate of two single-letter mutations per month could theoretically result in 2^10 different variants in less than a year. It almost certainly won't, because many of the mutations will be the same (some parts of the genome almost certainly are more likely to mutate than others). But a rate of 2 single-letter mutations per month, is not much of a limit. The nature article you reference (for which thanks, btw) says its mutation rate is about half of influenza's. Which is, yes, less, but that's still really fast compared to almost anything that isn't influenza. Even a slow-mutating virus is still mutating fast.
- deleted 6y ago
  [deleted]

HarryHirsch 6y ago

a virus new to humans, will evolve to become less likely to either kill the host Oh, come on, the pox had mortality > 30 %. Evolutionary pressure favours easy spreading.

SiempreViernes 6y ago
If you want to learn more about smallpox go to this url: https://ourworldindata.org/smallpox https://ourworldindata.org/smallpox
rossdavidh 6y ago
Sure, evolution pressure favors easy spreading, but if sick people stay home or go to the hospital, and non-sick people go out, then that pressure is to make the host sick less often. Early estimates for mortality in Wuhan were 3-5%. Later estimates kept dropping, and are now at 0.39%. Most viruses do not make the host sick, and the longer it's been in humans, the more likely it is that this is so. If the mortality rate is dropping (the article's assertion), but the WHO says none of the existing treatments has been shown to work, then the simplest explanation is that the virus has evolved in that direction. Given that the virus is very new in humans, there's nothing surprising about that.
- HarryHirsch 6y ago
  Coronaviruses mutate quite slowly, this one has been around for less than a year, you would not expect to see much change in virulence over that timespan. Any lowering of mortality is best explained by more thorough testing.
  - rossdavidh 6y ago
    From https://www.sciencedaily.com/releases/2020/04/200409085644.htm https://www.sciencedaily.com/releases/2020/04/200409085644.h... "There are too many rapid mutations to neatly trace a COVID-19 family tree. We used a mathematical network algorithm to visualise all the plausible trees simultaneously," said geneticist Dr Peter Forster, lead author from the University of Cambridge. Also here: https://www.sciencedaily.com/releases/2020/05/200505190550.htm https://www.sciencedaily.com/releases/2020/05/200505190550.h... "They identified 198 mutations that appear to have independently occurred more than once, which may hold clues to how the virus is adapting..." It may "mutate quite slowly" compared to, say, influenza, but compared to anything else it is mutating quite a lot, in only a matter of months. Virus generations are pretty fast.
    - HarryHirsch 6y ago
      This report takes the exact opposite viewpoint: https://www.nature.com/articles/d41586-020-02544-6 https://www.nature.com/articles/d41586-020-02544-6 "A typical SARS-CoV-2 virus accumulates only two single-letter mutations per month in its genome."
      - rossdavidh 6y ago
        Interesting article! But, from that very article: "Despite the virus’s sluggish mutation rate, researchers have catalogued more than 12,000 mutations in SARS-CoV-2 genomes." Now, that doesn't tell us that these mutations matter, but that's because we don't know which ones matter. But even a rate of two single-letter mutations per month could theoretically result in 2^10 different variants in less than a year. It almost certainly won't, because many of the mutations will be the same (some parts of the genome almost certainly are more likely to mutate than others). But a rate of 2 single-letter mutations per month, is not much of a limit. The nature article you reference (for which thanks, btw) says its mutation rate is about half of influenza's. Which is, yes, less, but that's still really fast compared to almost anything that isn't influenza. Even a slow-mutating virus is still mutating fast.
deleted 6y ago
[deleted]