4 ms·

Source on the first claim? The S/L strain study has been heavily challenged, see commentary at https://nextstrain.org/help/coronavirus/FAQ#is-one-strain-of-the

• KarlKemp 6y ago
  I do remember this phenomenon being mentioned quite a few times in my genetics classes. Don’t remember the name, unfortunately. But the logic is fairly obvious:a virus wants you to die just as little as humans want the earth to die. As I remember it, it probably wouldn’t make much of a difference here. The classic case mentioned were extremely fast & lethal viruses such as Ebola & Marburg: When a virus kills you within two or three days of infection, any small change can easily double that time and thereby gain significantly better chances of transmission. But for Covid (and, before that, HIV) the infectious period is pretty long already and any improvements would matter less in relative terms.
  • zbjornson 6y ago
    Pathogens can definitely evolve to improve fitness and settle into an ecological balance with their hosts. I more meant to contest that most start out very harmful. I don't think we have data to support that, or to be able to separate virus vs. host adaptations that would cause the appearance of lessened severity, given that most viruses circulating today have ancient origins.