Delta is less deadly because more people have some immunity, either because of vaccination or because they have already been infected. Also it came late in the game, and many of the people who are the most at risk are already dead. Treatment has improved too.
So the virus itself isn't less deadly, it is just that we are better prepared.
Fortunately this is the trend for most viruses. I have seen no evidence that the delta variant was more lethal, but that it was more transmissible. I have also seen numbers from my locality sequencing that suggested lethality was significant chunk less than that of alpha.
Delta-infected patients seem to be 1.8 times more likely to be hospitalised, compared to Alpha-infected patients [1]. Since the covid virus takes two weeks plus to kill its host and also spreads while the host is asymptomatic, there really isn't much selective pressure to make it less deadly. So far infectiousness and severity of disease has gone hand in hand with this virus.
I think I may be reading/interpreting your comment incorrectly after writing this/digging up these sources -
Whether or not Delta specifically is causing a larger impact on severity of outcomes, we know for a fact that it's more transmissible. And unvaxxed are quite literally dying 99:1 against vaxxed now - mostly from delta. Even if it's less likely to kill/cause severe irreversible organ damage per case, it seems somewhat safe to say the vast majority of unvaxxed are going to get it sooner than later at this point because of increased transmissibility - which will lead to a giant pile of bodies that didn't need to happen.
I would like to think that info alone probably indicates that delta is having a larger affect on the severity of outcomes, but I know there's more to statistical analysis than that. Anyways.
And, as expected, it appears to be far less harmful than Delta, which was less harmful than the original novel cov2. This is how a virus evolves, it gets weaker, which allows it to spread faster. Dead people don't spread viruses. It looks from the data that we are finally at the end of this pandemic.
True, though from my understanding, in some sense herd immunity was reached for the original strain and even delta, both of which are pretty much eradicated from the US.
Those were the deadliest strains as well.
What happened is that COVID started mutating much faster than expected in ways that it can avoid the immune system.
Please don’t spread the idea that viruses necessarily become more virulent and less lethal. I believed this prior to Covid, but have subsequently learned that it’s not a reliable assumption. It may be true in some cases, but I’ve seen several scientists cast doubt on it, and you can easily find research saying it’s not always the case. It hasn’t really happened with Covid—Delta was more transmissible and equally lethal, Omicron is massively more transmissible with only a modest reduction in lethality.
I suppose it depends on how you calculate it. If the delta variant is equally deadly to previous versions (to an individual), but is more infectious, then more people will die, all else being equal. More people dying --> more deadly, at the population level.
Delta was the dominant variant only by end of July so the data set for the 0.1 number could have been based mostly on a virus which is 2.5x less deadly.
We're now facing an endemic virus which, even with vaccination, approaches (or could get as bad as) the deadliness of the flu.
The article specified that high death rates might be expected for developing countries with low vaccination rates, not countries with high vaccination rates.
> So Delta, like Alpha before it, is both more transmissible and more fatal. Both of these effects have the same root: the virus is much better at binding to human cells, so it reproduces much faster.
> Are people dying more then? Not in Britain.
> But Delta is very hard in developing countries, especially in dense urban areas where the poor are forced to work but live in close quarters with many others. India, Argentina, Tunisia, South Africa, and Indonesia are very sad examples of this.
Viruses evolve to become more mild because very sick or dead hosts are bad spreaders.
Covid has a long incubation period before symptom onset (when somebody notices and isolates or becomes bed-bound). So Covid, especially Delta, spreads well for days, whether or not ultimately symptoms are mild or ultimately it causes death.
Therefore a mild version of Delta wouldn't necessarily outcompete a non-mild version of Delta, all other things being equal.
Is Delta more deadly? I thought that was not really believed to be the case any more, just that it is much more transmissible. I could totally be wrong though; it's hard to find reliable info.
Yeah, I think part of what is so vexing about Delta is that deaths don’t create a backstop against spread. Someone with a severe or terminal case of Delta can still infect 10+ individuals before they pass.
US deaths peaked in January 2021, before Delta became prevalent in the US, before substantial vaccination, https://www.worldometers.info/coronavirus/country/us/#graph-...
India (origin of Delta) deaths peaked in May 2021, when their vaccination rate was less than 5%, https://www.worldometers.info/coronavirus/country/india/#gra...
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