that is truly frightening. if thatās true, it seems like itād raise the spread in places like grocery stores, public transportation and the like quite a lot.
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wasnāt there a contingent of people claiming that mutation would inevitably make the virus less harmful over time?
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oh, yeahā¦ this guy favored by the trump administration.
[It] seems more probable than not that the total number of cases world-wide will peak out at well under 1 million, with the total number of deaths at under 50,000. In the United States ā¦ about 5000.
At some tipping point, the most virulent viruses will be more likely to kill their hosts before the virus can spread. In contrast, the milder versions of the virus will wreak less damage to their host and thus will survive over the longer time span needed to spread from one person to another. Hence the rate of transmission will trend downward, as will the severity of the virus. It is a form of natural selection.
This is what is normally expected. Decimating your hosts is not normally a good species survival trait. I think the definition of āover timeā is a little soft, plus we are at least trying to interfere with the natural evolution of the virus.
i still find that highly suspect. has this happened with any major infectious disease? polio is still polio, hiv is still hiv, malaria is still malaria. is there one that we can point to and say: it got less worse?
Obviously a mutation that makes it less contagious would be aggressively selected against, but from the virusā perspective the rest are mostly neutral, unless damage can drive people into more contact with others. Technically, at the point where the disease is threatening its host species with extermination, or maybe over the course of many generations then yeah, it would select eventually to be less lethal, but since typically itās gone through most of its infectious phase even before the symptoms have begun, it could care less about a now-used incubator.
A lot of diseases have mutated to be less damaging and therefore coexist with us better, but most of the examples Iāve heard of, weāre talking millennia.
Plus, with 7 billion people to burn through, pretty much no disease, no matter how terrible, has any fear of starving itself.
I had thought it was what happened to original SARS. Iām also under the impression that the symptoms of syphilis were formerly much more severe and that it basically evolved to be less harrowing because no one wanted to have sex with obviously sick people. I canāt find a reference for either of these so Iām currently assuming they are both BS.
id think thatās the key. it doesnāt really care if you live or die if it has already moved on. ( and thatās i think how this one works, youāre most infectious i believe right before and after you start showing symptoms - long before death )
there might theoretically be some selection pressure for a variant that doesnāt cause the host to show any symptoms, but we donāt really know why some people donāt have covid symptoms. it seems less about variants of virus and more about variation in the hosts.
and, what weāre seeing seems to be the opposite because itās still finding new kinds of hosts: namely younger hosts.
but really it seems a virus might even jump species before it mitigates its effects. it might even āsplitā into multiple variants that can each infect us separately. itās just not something we know enough to model.
which is why to me it seems saying whether we know any given virus is going to get better or worse or stay basically the same seemsā¦ suspect.
we do biology pretty well, but thereās still so much more we donāt know
yeah. this. 
One classic example is scarlet fever. The bacteria that causes it is still with us, remains common, and thereās never been a vaccine. It was a major killer of children in the 19th century and early years of the 20th century. But mortality rates dropped to almost nothing over a period of a few decades and by the time that antibiotics became a viable treatment there were almost no patients left who needed treatment.
That is definitely one. My grandfather lost his first son and possibly his wife to it, probably in the '30s. When my uncle got it, probably in the late '50s, early '60s my grandmother wouldnāt tell my grandfather what it was because he was so traumatized by it, even though the doctors had no concerns at that point.
Bubonic plague is also, apparently, much less dangerous than it was a mere 600 years agoā¦but still potentially lethal.
The usual example is the 1918 flu, but there is apparently a lot of disagreement over whether it applies more broadly. Here is a discussion of the issue; I found it a little depressing:
The idea that circulating pathogens gradually become less deadly over time is very old. It seems to have originated in the writings of a 19th-century physician, Theobald Smith, who first suggested that there is a ādelicate equilibriumā between parasite and host, and argued that, over time, the deadliness of a pathogen should decline since it is really not in the interest of a germ to kill its host. This notion became conventional wisdom for many years, but by the 1980s, researchers had begun challenging the idea.
- Increased urges to visit a gym/barber/hairdresser/church/rally/etc.
(Or did that one already sneak in?)
I still remember the report in December that mentioned transmission in 5 minutes. Not sure which variant was involved, but it was something I shared with family and friends to reinforce the message that just distancing indoors was not enough.
Just a followup, this completely preventable cluster at Kingās Cathedral & Chapels on Maui is now up to 90 cases. These guys have branches all over the country, and no respect for peopleās health, so watch out.
at least according to wikipedia, it seems that penicillin is the main reason we brought it under control - not a change in the virus ( oops, bacteria. thanks @DukeTrout ) itself.
especially this aspect, id imagine:
An infected individual is most likely to pass on the infection to another person during the first 2 weeks. A child is no longer contagious (able to pass the infection to another child) after 24 hours of antibiotics.
this other article though does talk about the idea of a less severe mutation having arisen, but also lists a few other reasonable possibilities:
Other biological factors such as herd immunity to epidemic strains, as well as social factors including decreased crowding, improved hygiene, and even milk pasteurization (milk was responsible for several large group A strep outbreaks) also probably contributed to this decrease.
to me it sounds like itās in the category of a strong āmaybeā, and still doesnāt say itās a given for any particular disease. ( it does have a really interesting history and itās not something id ever heard about! )
The rules are going to be different for bacteria than viruses. Viruses require a host to replicate. Bacteria can survive and replicate without a host.
All the more reason why itās not evolutionarily advantageous for a virus to kill its host! SARS disappeared pretty quickly in part because people who got sick often died quickly, and it was obvious when they got sick so it was easier to isolate them. A long, lingering disease with the possibility of pre-symptomatic or entirely asymptotic spread has more of a chance to get around.
Many of the most common viruses in the world (therefore, the ones that āwinā at evolution) tend to be the harmless ones we all have but that youāve never heard of since they donāt make you sick. In defense of viruses: Most are harmless, and many can be beneficial to us
Scarlet fever still exists, and still (very occasionally) causes severe illness or even death, but the advent of penicillin and its derivatives largely defanged it. Why it occasionally raises itās ugly head is still very poorly understood. Might have something to do with adaptation, but my theory is that strep just so rarely gets to run rampant anymore with easy (maybe too easy) access to highly effective antibiotics. Thatās not the whole story, though, and it is still an active research question.
I agree that antibiotics play a role in modern times but Iāve looked up a couple papers from the 1950s that very much donāt attribute antibiotics to the mysterious decline early in this century. It was definitely already in decline prior to the common availability of antibiotics.
Hereās a snippet from on 1950s paper:
The decline in mortality it describes here all occurred prior to the invention of penicillin antibiotics in 1928.
