This is what happened with "Marek's disease", a virus-caused disease in chickens. The vaccine was "leaky" and ended up selecting for a more deadly form, such that now all chickens worldwide have to be vaccinated for it or they'll die if they get infected - which didn't used to be the case.
https://www.scientificamerican.com/article/covid-variants-ma...
2) We can see with SARS and MERS that a more deadly form may actually reduce overall mortality, since the virus can't spread as effectively. However, we haven't had this effect so far.
Isn't it more significant not where they emerge (which is by random mutation) but where they do well? And don't they seem to do well in countries that have vaccinated more people?
Is it even particularly easy to say where a variant originated? Could the mutations happen multiple times independently?
Random mutation happens more when we give it more chances, by letting it infect more unprotected people. We'd rather avoid that, so it's also important.
>Is it even particularly easy to say where a variant originated?
No, but we have gene sampling to help.
>Could the mutations happen multiple times independently?
They can and sometimes do happen independently.
https://www.nytimes.com/2021/07/20/world/asia/india-covid-pa...
https://www.nytimes.com/interactive/2021/05/25/world/asia/in...
> Analysis of samples from the patient showed that the virus evolved rapidly after the plasma therapy, developing mutations that changed how it could infect cells and resist antibodies.
Seems to be that the plasma therapy (injecting antibodies) is responsible here.
https://www.npr.org/sections/goatsandsoda/2021/02/05/9644470...
As GP pointed out, when the unvaccinated are at risk and vaccinated ones are carriers, the dynamics don't remain the same as in the case of Ebola / Nipah / MERS / J. Encephalitis, because the infection retains its virulence while evolutionary pressure selects for a fatal variant, a deadly combination.
Marek's disease in chicken is what the PLOS article is about: MDV = Marek's disease virus.
> The vaccine was "leaky" and ended up selecting for a more deadly form
The researchers of the PLOS article do not claim to know that for certain:
"Our data do not demonstrate that vaccination was responsible for the evolution of hyperpathogenic strains of MDV, and we may never know for sure why they evolved in the first place."
But this they claim:
"But whatever was responsible for the evolution of more virulent strains in the first place (and there may be many causes), our data show that vaccination is sufficient to maintain hyperpathogenic strains in poultry flocks today."
https://journals.plos.org/plosbiology/article?id=10.1371/jou...
1) the most contagious variants have emerged from countries with little to no vaccination: UK before vaccination and with very little protective measures (pubs, etc.), Brazil with Bolsonaro, India with a very high population density who are mostly unvaccinated, etc. These variants appear thanks to the high number of contaminations. Vaccination means fewer contaminations, and thus the less likely arising of mutations and a new variant.
2) Current vaccines are very effective against the current variants. This observation is inconsistent with the assumption that one of the variants could have been naturally selected to resist to vaccination. This is also expected as the percentage of vaccinated people is low in most parts of the world, thus there is little pressure to select a vaccine-resistant variant for now.
If we had made the variants "worse" because of imperfect vaccination, we would have seen a vaccine-resistant variant emerge from one of the vaccinated (>50%) countries.
I agree that the idea that vaccines are leading to new variants seems extremely dubious though. Like everything else in epidemiology, when you go looking for the underlying rational basis for it, there's just nothing robust there.
If the vaccinated aren't spreading it then you're suggesting that the unvaccinated have become drastically more infectious for no apparent reason and in ways that don't show up in contract tracing data. I think the alternative explanations are more likely to be correct: the vaccine is actually not a vaccine in the traditional sense, it's more like a prophylactic. Vaccinated people aren't getting an immune response in the normal areas where it would usually enter and exit, like the nose and lungs, instead it's being injected into the arm.
Also, COVID tests don't actually detect COVID or even SARS-CoV-2, they detect RNA debris from destroyed SARS-CoV-2. Thus it's expected that if someone's body fights off the virus immediately if they're exposed to it, they will still test positive.
> Also, COVID tests don't actually detect COVID or even SARS-CoV-2, they detect RNA debris from destroyed SARS-CoV-2. Thus it's expected that if someone's body fights off the virus immediately if they're exposed to it, they will still test positive.
Slightly untrue. The particles gathered from infected and spreading persons are fully functional, by definition. To distinguish these cares from immune people, one would have to determine the percentage of viable virus particles. Hard to tell whether that's even feasible at scale. It's not too bad though. At worst this causes a higher than expected false-positive rate.
"one would have to determine the percentage of viable virus particles. Hard to tell whether that's even feasible at scale ... It's not too bad though. At worst this causes a higher than expected false-positive rate."
I'm not sure you're aware of the scale of the problem. There have been studies that correlated PCR test results with ability to do viral culturing and concluded about 60% of all positive test results did not imply infectiousness. For example, this one:
My point was that the viral culturing might not be feasible for large-scale testing. In that case, we might have to stick to PCR.
The correct response to the PCR not detecting what people actually need to know is to shut down mass testing entirely. There is no point in mass testing if it creates chaos and doesn't help, which is what's happening (there is no correlation between testing levels and incidence levels, killing the theory that test test test = better results).
Isn't that the point of concern about the variants? Alpha is vastly more infectious than the original and delta is even more infectious than Alpha, which is the reason why they're able to become the dominant strain in unvaccinated populations (england in early 2021 & india with delta). Both have some immune escape but less than e.g. the gamma variant which hasn't become dominant in most countries with high vaccination rates.
(now, since the covid vaccines don't mean complete sterile immunity, just like all others, increased infectiousness also leads to problems)
The PCR tests do detect the virus if the body fought of the virus immediately, but can also measure the amount remaining (the cycle count) which has a cutoff point. Thus it often doesn't get counted as "infectious".
The antigen tests (the fast, cheap ones) don't trigger on small amounts, also leading to issues and that results in them being more-or-less useless to detect infected vaccinated people.
Re: PCR:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8166461/
In light of our findings that more than half of individuals with positive PCR test results are unlikely to have been infectious, RT-PCR test positivity should not be taken as an accurate measure of infectious SARS-CoV-2 incidence. Our results confirm the findings of others that the routine use of “positive” RT-PCR test results as the gold standard for assessing and controlling infectiousness fails to reflect the fact “that 50-75% of the time an individual is PCR positive, they are likely to be post-infectious”
There is hope, we might not get rid off it but if we could control chickenpox that is quite more infectious, we can have a little hope. Even more with more modern medicine.
Well. So it was in our tentative models at the time of this author's writing (8 days). So it is not any more, as of a few days only (3 days).
...Ray Kurzweil was right. /Bitter Joke.
"selfish" implies you think there is some benefit to those individuals in declining it. What do you think that is?
Even if you have unshakeable faith in this evidence-free perversion of biological theory, nobody was claiming the vaccines will fail without 100% adoption last year when they launched. Their reception would have been rather different if that had been claimed, wouldn't it? So you can either believe this is true, in which case governments and pharma firms deceived people about the nature of the 'vaccine', or you can believe it's false and they didn't. But you can't believe it's true and it's the other people who are deceivers. That makes no logical sense.
Global eradication of diseases has been achieved with smallpox and bovine rinderpest precisely because they had no natural reservoir and all vulnerable populations could be vaccinated. With Coronaviruses the situation is not so simple, but it should at least be possible to eradicate the currently relevant variant.