Also the natural selection on viruses would result in them evolving into less deadly forms because those would be the ones that get more wide spread.
Other factors like long incubation and infectiousness are also often inversely correlated the incubation period is the time when the virus replicates while remaining mostly asymptomatic which often means for airborne viruses it’s also a period when the host isn’t particularly infectious.
And yet here we are with a virus that has an r0 much higher than flu, and is ~10 times more lethal.
That the two things are correlated in certain modeling scenarios does not mean you can't end up something that both spreads and kills.
Lethality estimates also suffer from being based on bad data. “Patients who have been tested for SARS-CoV-2 are disproportionately those with severe symptoms and bad outcomes.” [1]. For that reason, the CFR in the US at least has been around 1%, but the IFR could actually be significantly lower.
[0]: https://www.ncbi.nlm.nih.gov/pubmed/19545404/ [1]: https://www.statnews.com/2020/03/17/a-fiasco-in-the-making-a...
In terms of estimating the IFR, it's hard; estimates are about 0.7, much higher than flu.
Your link says 'mean R0 1.3: range 0.9 to 2.1'.
Compared to the mean R0 of flu, this disease spreads substantially more and is more lethal, hence is a good counterpoint to the flawed argument of the post that I was replying to.
When it will be it can also be used to easily create a cure if you can assemble viruses like legos it would be also incredibly easy to create inhibitors and anti bodies with the same technology.
This is also what we are doing atm basically playing a huge game of “Perfection” by trying to find anything that would fit one of the “holes” on the virus, our cells or those which open up during its assembly process like its viral protease.
I've heard a firsthand account from a guy who worked at Vector [0], that they had difficulty controlling viruses [1]. Accidental releases of weaponized bacteria also happened [2], but in that case they could prophylactically treat with antibiotics. That said, this was done using 1970's-1980's technology. I'm sure there's some more sophisticate bioweapons that are possible now. Maybe viruses are a more reasonable chassis.
[0] https://en.wikipedia.org/wiki/Soviet_biological_weapons_prog...
virus is good for control in the case of accidents such as a biowar implement crashes somehow and spills virus, the environment will destroy it quickly, the cleanup is simple compared to a bacterial agent, eg anthrax in spore form lasts many years-->
This virus has shown the widespread economic impact and unpredictability that the uncontrolled spread of a virus can unleash on the world.
After this, I'm sure no superpower will want to take a chance releasing a weaponized pathogen: it might just come bite them back in the ass.
The answer was that this is very unlikely. In fact, the evolutionary direction of all known viruses is the opposite: from high towards low virulence. High virulence is observed in viruses which have recently jumped from one species to another and can be thought of as temporary maladaptation to the new species. As the virus adapts, the damage it does in the course of its reproduction process becomes less and less severe. Eventually, many viruses end up causing mild symptoms similar to the common cold, warts etc.
This is covered in ch. 64-66 of Quammen’s “Spillover”, which covers a seminal paper by Anderson and May[0] considering the case of myxomatosis.
Here’s some salient quotes:
Laboratory experiments showed that all field strains produced lesions that provided sufficient virus for transmission to occur,” he wrote. But the strains of very high virulence (grades I and II) killed rabbits “so quickly that infectious lesions were only available for a few days.” The milder strains (grades IV and V) produced lesions that tended to heal quickly, he added—and then the payoff, “whereas strains of grade III virulence were highly infectious for the lifetime of the rabbits that died and for a much longer period in those that survived.” Grade III, at that point, was still killing around 67 percent of the rabbits it touched. Myxoma virus, thirty years after its introduction, had found this level of virulence—being pretty damn lethal—to maximize its transmission. It was still capable of killing most of the rabbits it infected, but capable also of assuring its own survival with a continuous chain of infections. The first rule of a successful parasite? Myxoma’s success in Australia suggests something different from that nugget of conventional wisdom I mentioned above. It’s not Don’t kill your host. It’s Don’t burn your bridges until after you’ve crossed them...
...they[Anderson and May] plotted a relationship between virulence and success. Their result was a model-generated prediction: Given this rate of transmission, given that rate of recovery, given those unrelated mortalities, then . . . an intermediate grade of virulence should come to predominate. Son of a gun, it matched what had happened.
[0]: https://www.cambridge.org/core/journals/parasitology/article...
Thus, testing is by far the most important capability to have - it is a litmust test whether the pathogen is ready to build one of those bridges to cross.
As I recall, the virus in The Stand had a death rate of something like 99.4%.
However, if that actually happened, it seems like there would still be enough people to make a medium sized country, and wouldn't it rapidly evolve to be less virulent anyway?
But anyway, just on my vague sense of fate, this all might be an omen for what happens in ten or twenty years. I keep thinking of the 20th century kind of echoing, first there was WWI, the flu epidemic, the depression, WWII...early on you couldn't have imagined what was coming.
its a luck of the draw and then selection for most apt to produce offspring.
the virus can become more lethal in effect over time, or take on troublesome characters such as asymptomatic contagion with extended incubation period.
the virus is so problematic right now due to a sponteneous mutation altering its previous character.
Any virus is reproducing as it spreads, so it seems to me impossible for there not to be evolution happening. Milder illness enhances the spread, so it's going to be selected for. What is the counterargument?
directional selection is a very different thing it exists, it is part of evolutionary theory, it means there is a bias toward a particular allele [natural selection is a form of directional selection.
selection does not lead to a path of improvements, it leads to changes in frequencies of phenotypes.
there are other ways of enhancing spread, and retaining lethality, such as being communicable before symptoms become debilitating, this removes selective pressure that is based on communicability. If the host does not get sick enough to to be bedridden, they can contact other hosts. If the symptoms are mild or unseen there is no behavioral basis for other hosts to avoid the infected host. so by delaying expression of characteristics the virus may be highly communicable and highly lethal at the same time. high lethality is not subject to selective pressure in this case and will remain.
I don't know what that means or what your source is. It sounds like you're maybe saying that orthodox evolution theory doesn't apply when humans are involved. Why, what is the mechanism?
And how exactly do you get from the idea of a pathogen evolving to be less virulent to "artificial" selection? Stipulating that somehow artificial selection is different, what would make it artificial? It seems obvious that human behavior would factor in, but what is the definition that makes the evolution artificial?
https://en.wikipedia.org/wiki/Directed_evolution
...and this means directed selection is not an natural process by definition. natural evolution doesnt proceed toward a defined end, [bipedal primates with large cerebrum] [or from highly lethal-->moderately lethal-->nonlethal]
virus do not start from day one as very lethal and become progressively less lethal over successive replications.
communicability is an advantage to host to host transmission. breaking linkage between traits allows differing selective factors to act on these traits.
when a virus doesnt kill you or make you ill until after you have infected others then that virulence is not subject to the same selective factors as it previous partner [communicability]
It's a matter of degree, not a binary thing. You can't be 100% sure of anything, but as long as people are aware of something and act accordingly, there will be selection pressure. Reduced social contact has an effect regardless of whether specific carriers are identified.
are virus always absolutely lethal and then lose lethality as they evolve?
or do virus of non lethal character spontaneously become more lethal?
So, specifically in answer to your question, it seems obvious to me that "lethal characteristics" are context dependent, so they come from random chance when an organism (or virus) encounters a new environment that it can replicate in way easier.
when a virus has infected a host, replicated, passed to a secondary host, then symptoms appear, then X occurs,
You have a situation where X has no influence on reproduction, replication or transmission, it just is not even on the same blackboard as that equation.
here is some suggested reading for you, not everyone understands evolution or natural selection very well so it is a bit of a TLDR
It is true that a basic law of reality/nature is that causes must precede effects, so in a sense, I think I agree your statement is technically correct regarding the exact cycle you describe.
But when talking about evolution in a population, the cycle happens a huge number of times. So "X" will influence all of the instances of replication that in fact happen after it. It would be silly to talk about evolution in a context of one and only one reproduction event.
I don't think we are debating anything that has to do with specialist knowledge of viruses.
How many times do we see this sort of thing in nature? We do see infestations, like beetles destroying forests, but I'm not so sure we have many cases where we expect viral infections to be the likely candidate.
Of all the disease related scenarios I'm worried about, none match your scenario. I do think in some ways humans are "tuned" to apocalyptic thinking moreso than is perhaps is helpful. I think we're more prone to accept emotional arguments than we should be, causing us to possibly be more a danger to ourselves in the face of a terrible disease than the disease itself. I'm much more afraid of what we'll do to each other and ourselves, willingly, under pressure, than I am about even the most deadly viruses will do.
Having said all of this: it's all opinion and none of it comes from expertise. Others may point out evidence to the contrary.
Modern medicine and hygiene would have significantly increased survival rates, especially since many of the most deadly plagues are thought to have been bacterial and transmitted by flea bites. The other big difference is transport of course; historically extremely virulent and deadly diseases in many parts of the world had limited ability to spread beyond that particular ill-fated town or city, and rats and fleas were more necessary as well as more effective in helping the disease spread.
Certainly more than just "one little impact in Russia".
And when the supply disrupts, the most readily available supply will be ... other humans.
The real danger would be if it stays in a host like bubonic plague, and even if you survive the direct human transmission, it still gets to you...
Also, those death rates were supposedly what native americans suffered when exposed to european diseases.
It's only a few mutations away from human to human transmission.
It also doesn’t survive long at 37c or higher temps (6 days at 37c and drops fast from there).
Birds have higher body temperatures which helps to regulate the virus so while they can be carriers they are usually asymptomatic since the virus can’t replicate fast enough to cause major issues.
There's absolutely no indication of this. Please don't spread harmful misinformation.
Here's the latest reason you're wrong. It's a link to a tweet from the governor of NY. Same has been reported in multiple countries in Europe. When ventilators run out, even young people start dying. The death rate in Italy is already higher than 1-3%, especially if you calculate (num recovered)/(num recovered + num dead).
There are dozens of reasons not to trust the Chinese numbers - statistically perfect (Reg coeff>.999) quadratic growth curve, claims of all being well while pollution maps showed nationwide shutdown, admonishment and disappearance of whistleblowers, including doctors, scientists, billionaire tycoons, and activists...it's all been floating around the internet since January. Little of it is picked up by "official" sources because when a government shuts down any unapproved media in a nation without free speech, people can only leak through channels like WeChat screenshots, tweets and Twitter videos. But the rationale makes sense in addition to the wealth of circumstantial and empirical evidence.
An authoritarian, autocratic nation can only rule so long as the people are kept by respect and/or fear from revolting. That is why the CCP has a history of controlling narratives to save face. This is not unique to the CCP, which is an offshoot of the former CCCP which practiced the same manipulation for most of it's history.
The CCP spent two critical months trying to hide this from the world, and now we are all going to pay for it. Do not let their propaganda machine set the narrative. This is not a reflection on the Chinese people, their hands are tied by a self-preserving bureaucracy.
So far in Italy the death rate under 40 is tiny.
How many other pandemics have infected multiple world leaders? Do you know that within a week of Iran announcing an outbreak, 8% of their parliament was infected and two members dead? R0>3 is not hard to believe. There's a reason a dozen European countries are on lockdown.
It was widely used during the HIV epidemic to provide pre-trial access to medications and my hypothesis is that the program will be used even more extensively for sars-cov-2.
If your country does not have a law like this, now is the time to push your representatives.
Note - this is different from allowing OTC access to chloroquine willy nilly. If that is the suggestion, I am in agreement with the government that physician mediated access is the wisest course. While we know the safety profile of the medication, the doesn't make is "safe".
First rule of power: never waste a crisis. If we cure this thing now, before the destruction of all personal freedoms is complete, people won't be willing to go quietly into the totalitarian night. Therefore, it is critical that even news suggesting there might be a cure be suppressed.
Notice how for every one article you can find about the promise of Cholorquine + Azithromycin, you'll find 10,000 all talking about how it's a hoax/lie/fabrication, or else that more study is needed -- at least another 12/18/36 months? All long enough to ensure that the dismantling of our society can be completed before anybody can be treated.
A virus with the combination of all of the aforementioned properties would guarantee complete extinction of humans (or we get very close to it). Should we consider ourselves lucky?
Edit: my intent wasn't to incite panic, but to learn about the virology, molecular biology and the physics of transmission.