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SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

biorxiv.org

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Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#31

Post by johnchristopher »

djsumdog wrote: post #26
packetlost wrote: post #16

Earlier quoted context omitted.

The h1n1 is a bit of a strange case though because it jumps species boundary very often and mutates very quickly. COVID-19 appears to evolve much, much slower. Based on my limited understanding of virology, I think this means it's unlikely to become a seasonal problem unless the general populations immune system does not retain immunity to the same strain for a significant period of time.

We already know CoV2 rarely causes any symptoms in children. I wonder if there was a time in prehistory where common Rhinoviruses and Coronaviruses wiped out larger populations of elderly. Even if our immune system memory doesn't last very long for these types of viruses, wouldn't young people getting exposed to it now likely reduce its impact long term? It also seems like >95% of people who die from this are over 55…

> We already know CoV2 rarely causes any symptoms in children. I wonder if there was a time in prehistory where common Rhinoviruses and Coronaviruses wiped out larger populations of elderly.

Didn't pneumonia, influenza (among small pox and others) have terrible consequences on American native Indians ?

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#32

Post by sp332 »

cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

But the way viruses evolve to be less deadly is that the deadlier strains kill a bunch of people quickly, before they can spread too much. So that's not exactly reassuring for any given mutation.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#33

Post by jfoster »

feanaro wrote: post #28
throwaway2245 wrote: post #25

Earlier quoted context omitted.

Conventional wisdom often claims that virus evolve to become less fatal - but I don't think that matches the historical record. There's evidence for influenza virus existing thousands of years before 1918. As such, it seems to have evolved into a much more deadly strain at that point. Reproducing more efficiently is a win for natural selection and will normally result in a dominant strain: whether that strain is more…

> Reproducing more efficiently is a win for natural selection and will normally result in a dominant strain: whether that strain is more deadly or not is going to be random. The conventional wisdom is such because a virus that is swiftly fatal and/or has more dramatic health consequences would have less chance to propagate to other hosts. For instance, because the original host will be unable to move or will look thr…

Taken to extremes, it's easy to see how a virus that is 50% fatal within 24 hours will not last long itself.

Is there really very much selection pressure between 1% and 2% fatality rates over 4 week timespans, though? Especially if immunity is conveyed by infection, I don't see any reason why a virus like that would evolve to be less fatal within the timescales that humans care about.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#35

Post by scotty79 »

cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

Only if they are so deadly that it's harming their transmissibility.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#37

Post by davidf560 »

cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

I keep wondering what unintended consequences our nearly-unprecedented efforts on non-pharmaceutical interventions ("lockdown", social distancing, masks, etc.) might end up having on the virus - for example, could all our isolation and distancing be accidentally selecting for strains of the virus that transmit more readily over further distances?

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#38

Post by Zenst »

cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

That is mostly due to the way they are spread as a less impacted infected person would be more outgoing and spread that virus more. When somebody more impacted by a virus would be more isolated due to the impact. So the less impacting one gets more exposure and spread.

So that in itself would be a factor, however virus can mutate in various ways and it is the mutations that effect the incubation period and that window of being infectious but not showing any symptoms - that is always going to impact things and certainly a large factor in why COVID managed to spread better than expected.

But much hindsight and data analysis will play out for years and years, after all - we are still looking at the Spanish flu data and seeing different aspects to this day.

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#39

Post by BlueTemplar »

2f3f23f32 wrote: post #13
cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

The COVID-19 mortality rates are dropping all the time and are at 0.2% now (barely higher than normal flu). I see no reason to prevent the virus from spreading now because it is not dangerous anymore.

What about the crippled survivors?

Re: SARS-CoV-2 spike D614G variant confers enhanced replication and transmissibility

#40

Post by Zenst »

davidf560 wrote: post #37
cephaslr wrote: post #8

Something I have been wondering about, wouldn't a virus naturally evolve to be less deadly and more contagious over time? I.e. virus's tend to achieve a steady state like the cold and flu in the long run. If you are too deadly it hinders spread so I would expect Covid to get less deadly and more contagious over time, which kind of fits the data?

I keep wondering what unintended consequences our nearly-unprecedented efforts on non-pharmaceutical interventions ("lockdown", social distancing, masks, etc.) might end up having on the virus - for example, could all our isolation and distancing be accidentally selecting for strains of the virus that transmit more readily over further distances?

That will be a tough one to measure.

However measurement of the impact of lock-downs/social distancing upon existing known virus's like colds and flu's would give an insight into that whole area.

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