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The mutation that helps Delta spread

nature.com

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Re: The mutation that helps Delta spread

#21

Post by desine »

silicon2401 wrote: post #14
nonbirithm wrote: post #6

Is it implausible to think that continued transmission and mutation at this rate will cause a catastrophic worsening of the pandemic to an extent several orders of magnitude above what it is now? Vaccination is effective in the current state of the pandemic, but what's to prevent the built-up immune response of humankind being wiped out if the virus adapts enough?

People believe what's comfortable/convenient, not what's true. In very early 2020, when I was following the news of the virus development in Wuhan, China, I felt like a conspiracy theorist pointing out to friends and coworkers that a bad epidemic spreading in one of the most crowded parts of the world. They thought it was ridiculous to say that hospitals were getting overwhelmed, people were being quarantined etc. Do…

>We can reasonably say the Black Death killed 30% of Europe's population. We can't reasonably say covid won't do the same. All optimistic projections so far have been proven wrong, so all we can say for sure is that humans are terrible at predicting the future.

I think Black Death had quite a bit higher mortality than any version of covid we will see

Re: The mutation that helps Delta spread

#22

Post by tehjoker »

f38zf5vdt wrote: post #11
tehjoker wrote: post #2

Is there any information on what the upper bound might be on the infectivity of SARS-CoV-2? I think a lot of people just assume one big jump consumes most of the range, but we've seen at least three big jumps so far ("Doug", "Alpha", and "Delta").

Measles is estimated to be about 300% more infectious than the delta variant, so if it surpassed measles it would be the most contagious viral disease known to man. It's already pretty close to what is assumed to be the "ceiling".

300% is still a lot of room to grow. Delta is only about twice as bad as the wild type strain.

Re: The mutation that helps Delta spread

#23

Post by erokar »

walterbell wrote: post #13

Since the deadliest virus mutations kill their hosts, weaker virus mutations can spread (without killing their hosts) more quickly. US deaths peaked in January 2021, before Delta became prevalent in the US, before substantial vaccination, https://www.worldometers.info/coronavirus/country/us/#graph-... US daily vaccines peaked in April 2021, https://ourworldindata.org/grapher/us-daily-covid-vaccine-do... India (origin…

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.

1. https://www.bloomberg.com/news/articles/2021-07-23/what-make...

Re: The mutation that helps Delta spread

#24

Post by cjfd »

nonbirithm wrote: post #6

Is it implausible to think that continued transmission and mutation at this rate will cause a catastrophic worsening of the pandemic to an extent several orders of magnitude above what it is now? Vaccination is effective in the current state of the pandemic, but what's to prevent the built-up immune response of humankind being wiped out if the virus adapts enough?

Both the worst-case and the best-case scenario are on the table. Only time will tell what happens. As you seem to be focusing on the worst-case scenario I will talk about the best-case scenario. The best-case scenario is that the human immune system is getting used to corona with even vaccinated people spreading the delta variant with little chance of getting very ill. This will turn covid-19 into something like the common cold or possibly the flu. Who knows what will actually happen? Both my best-case scenario and your worst-case scenario can happen. I think, though, that one should not only focus on the adaptability of the virus. The immune system also has been doing defense against various pathogens for many millions of years.

Re: The mutation that helps Delta spread

#25

Post by slumdev »

selimthegrim wrote: post #15
slumdev wrote: post #8

Earlier quoted context omitted.

SARS-CoV-2 has four antigens. The existing vaccines stimulate the production of antibodies against only one of them, the spike protein. The existing vaccines are proving ineffective against Delta because it has mutated significantly enough that its spike protein does not cause a neutralizing immune response. They may even be causing ADE, as evidenced by the most recent data comparing Israel and Palestine.

Uh... citation? And as you know, neutralizing response is not the only type.

A study demonstrating the mechanism for Delta ADE in vivo: https://pubmed.ncbi.nlm.nih.gov/34384810/

Highly-vaccinated Israel's third-wave surge in both cases and deaths: https://www.worldometers.info/coronavirus/country/israel/

Unvaccinated Palestine's lack of third wave deaths: https://www.worldometers.info/coronavirus/country/state-of-p...

Re: The mutation that helps Delta spread

#26

Post by RC_ITR »

shreddit wrote: post #19
redisman wrote: post #17

Earlier quoted context omitted.

Deaths are down because we vaccinated all the old people who were dying in the first waves

Why would you vaccinate a dead person?

We vaccinated all the old people, who were the population most at risk for death the first time.

Re: The mutation that helps Delta spread

#27

Post by walterbell »

erokar wrote: post #23
walterbell wrote: post #13

Since the deadliest virus mutations kill their hosts, weaker virus mutations can spread (without killing their hosts) more quickly. US deaths peaked in January 2021, before Delta became prevalent in the US, before substantial vaccination, https://www.worldometers.info/coronavirus/country/us/#graph-... US daily vaccines peaked in April 2021, https://ourworldindata.org/grapher/us-daily-covid-vaccine-do... India (origin…

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. 1. https://www.bloomberg.com/news/article…

> Early data from Scotland indicated that delta-infected Covid patients were 1.8 times more likely to be hospitalized than those with an alpha infection. Other U.K. data support the increased risk of hospitalization but do not provide clear evidence that delta patients experience more severe illness once in the hospital.

How do hospitals identify individual patients infected by Alpha, Delta or other variant?

Do they perform genetic sequencing of a virus sample from each patient, to determine what mutations are present? If they are doing statistical sampling, what percentage of patients are being sampled for variant identification?

It would helpful to have variant-specific numbers of cases and deaths added to national data, so that accurate graphs can be drawn for each variant. More granular data would support data analytics of local, variant-specific, policy interventions, to evaluate cause-effect on local health metrics.

Re: The mutation that helps Delta spread

#28

Post by slumdev »

YPCrumble wrote: post #20
slumdev wrote: post #8

Earlier quoted context omitted.

SARS-CoV-2 has four antigens. The existing vaccines stimulate the production of antibodies against only one of them, the spike protein. The existing vaccines are proving ineffective against Delta because it has mutated significantly enough that its spike protein does not cause a neutralizing immune response. They may even be causing ADE, as evidenced by the most recent data comparing Israel and Palestine.

Do you have a source for the recent data on ADE? I searched and didn’t find anything suggesting this. The only thing I see are studies that more vaccinated people are dying in Israel, but that is to be expected because the older people are, the more likely they are to be vaccinated and they have less immune response to the vaccine. Source https://twitter.com/rzioni/status/1426178482569109504

See my reply to a sibling comment. The most damning evidence comes from the comparison between highly-vaccinated Israel, where there are many third-wave deaths, and mostly-unvaccinated Palestine, where there isn't a third-wave death spike at all. Having mostly-unvaccinated Palestine as a control group is showing us that we don't know what we thought we knew.

Re: The mutation that helps Delta spread

#29

Post by marricks »

tehjoker wrote: post #22
f38zf5vdt wrote: post #11

Earlier quoted context omitted.

Measles is estimated to be about 300% more infectious than the delta variant, so if it surpassed measles it would be the most contagious viral disease known to man. It's already pretty close to what is assumed to be the "ceiling".

300% is still a lot of room to grow. Delta is only about twice as bad as the wild type strain.

I'm not sure "only twice as bad" paints an accurate picture.

- Herd immunity is much harder. Calculated as 1 - 1/r0 where r0 is defined in relation to transmissibility. So if r0 = 3 that's ~66% need to be immune to stop the virus. If r0 = 6 that's 83% needed, much higher threshold.

- The virus is only getting more deadly. A preprint study found delta has "120% greater risk of hospitalization, 287% greater risk of ICU admission and 137% greater risk of death"[1]

Also 225% more transmissible is 3x more unless I'm doing my math wrong?[2]

[1] https://en.wikipedia.org/wiki/SARS-CoV-2_Delta_variant#Virul...

[2] https://en.wikipedia.org/wiki/SARS-CoV-2_Delta_variant#Trans...

Re: The mutation that helps Delta spread

#30

Post by Mordisquitos »

nonbirithm wrote: post #6

Is it implausible to think that continued transmission and mutation at this rate will cause a catastrophic worsening of the pandemic to an extent several orders of magnitude above what it is now? Vaccination is effective in the current state of the pandemic, but what's to prevent the built-up immune response of humankind being wiped out if the virus adapts enough?

No, it is not implausible in the sense that "it could never happen". However, neither was it implausible for this to have happened with the myriad of other viruses which have jumped into our species across our natural history—and yet here we are.

Remember there is no motivation behind the virus to adapt, nor such thing as "wiping out" the immune response. At most, there are random mutations which, if they are more successful than the previous ones, will become more widespread than their alternatives.

Are mutations that are less sensitive to current populations' immune responses more likely to succeed? Yes, of course! But there is a practical limitation to how much a virus can accumulate mutations which evade immunity to previous variants: it must not break its ability to infect (human) cells. Eventually an equilibrium is reached, as it has thousands of times previously.

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