Question about COVID variants

[Lemon Drop]

https://apnews.com/article/coronavirus-v...d6edbaf870

Reading about the so-called South African strain, recently discovered in 2 unrelated people in South Carolina, neither of whom have traveled recently. Can a virus mutate in different regions of the world and develop an identical variant? Meaning the variant spreads geographically without being spread by people. If that makes sense.

Or does discovery mean it was spread via human travel? And that there is now community transmission of this much worse variant. ( oh great)

[sekker]

Most likely is human travel, but it's technically possible for the same variant to evolve more than once.

[rjmacs]

Viruses can mutate in different places in similar ways, but there are generally ways to determine the particular history of a given variant by studying its genetic sequences. As I understand it, any given variant won't be 100% homogeneous in composition, and the variability present in a sample of a virus variant can tell you a lot about its particular history.

[Sarcany]

It would be remarkably rare for a new variant to spontaneously appear with the same exact mutations in the same places as one of the previously identified variants, but it's within the realm of possibility. (On the order of falling out of an airplane and surviving twice I'd imagine.)

Least untenable hypothesis would be that any matching strain that appeared first in South Africa and then a month later in Maryland was carried to Maryland rather than spontaneously arising in Maryland.

[sekker]

Sarcany wrote:
It would be remarkably rare for a new variant to spontaneously appear with the same exact mutations in the same places as one of the previously identified variants, but it's within the realm of possibility. (On the order of falling out of an airplane and surviving twice I'd imagine.)

For a single nucleotide change that results in hyperactivity, it's possible that there could be separate selection for a specific mutation.

But these more recent variants have over 10 changes; no way those are separate events.

[Speedy]

Not so fun reads:

https://www.washingtonpost.com/world/202...nt-manaus/

https://www.washingtonpost.com/world/afr...story.html

[PeterB]

sekker has it right. The most likely explanation is -- unfortunately -- previously-undetected community spread.

That being said, it definitely IS possible for the same mutation to occur simultaneously and independently.

And... and this is a BIG "and"... there has been very little discussion so far of the possibility of viral swapping of mutations by way of simultaneous co-infection with different strains either of SARS-CoV-2 or of other coronaviruses which are quite common in the environment (typically giving more typical common cold/flu symptoms).

There HAS been some discussion of the fact that we may be inadvertently selecting for mutations with people who are infected for an extended period and then undergo various treatments which, for various reasons, may not be fully effective ... so then you are effectively selecting for mutations in the virus which help it evade the treatments. Somewhat akin to what happens when you don't use the full dose of an antibiotic on a bacterial infection and you end up selecting for some mutant form of the bacterium that has partial or full resistance to the antibiotic.

[Ted King]

PeterB wrote:
sekker has it right. The most likely explanation is -- unfortunately -- previously-undetected community spread.

That being said, it definitely IS possible for the same mutation to occur simultaneously and independently.

And... and this is a BIG "and"... there has been very little discussion so far of the possibility of viral swapping of mutations by way of simultaneous co-infection with different strains either of SARS-CoV-2 or of other coronaviruses which are quite common in the environment (typically giving more typical common cold/flu symptoms).

There HAS been some discussion of the fact that we may be inadvertently selecting for mutations with people who are infected for an extended period and then undergo various treatments which, for various reasons, may not be fully effective ... so then you are effectively selecting for mutations in the virus which help it evade the treatments. Somewhat akin to what happens when you don't use the full dose of an antibiotic on a bacterial infection and you end up selecting for some mutant form of the bacterium that has partial or full resistance to the antibiotic.

It seems like the volume (figuratively) of infected individuals would be big factor in the likelihood of a nastier strain entering into our communities. Hopefully, the vaccines will deflate the volume of infections quickly enough to prevent some really nasty strain from evolving.

[PeterB]

Ted King wrote:
[quote=PeterB]
sekker has it right. The most likely explanation is -- unfortunately -- previously-undetected community spread.

That being said, it definitely IS possible for the same mutation to occur simultaneously and independently.

And... and this is a BIG "and"... there has been very little discussion so far of the possibility of viral swapping of mutations by way of simultaneous co-infection with different strains either of SARS-CoV-2 or of other coronaviruses which are quite common in the environment (typically giving more typical common cold/flu symptoms).

There HAS been some discussion of the fact that we may be inadvertently selecting for mutations with people who are infected for an extended period and then undergo various treatments which, for various reasons, may not be fully effective ... so then you are effectively selecting for mutations in the virus which help it evade the treatments. Somewhat akin to what happens when you don't use the full dose of an antibiotic on a bacterial infection and you end up selecting for some mutant form of the bacterium that has partial or full resistance to the antibiotic.

It seems like the volume (figuratively) of infected individuals would be big factor in the likelihood of a nastier strain entering into our communities. Hopefully, the vaccines will deflate the volume of infections quickly enough to prevent some really nasty strain from evolving.
The problem is, the strains we've recently identified mostly seem to increase infectivity, which means we'll be seeing a LOT more people infected, even if those people survive. While they're infected, their bodies serve as a potential "melting pot" for viral evolution. The longer they're infected, the more likely their body will allow some mutation. Some of those folks I mentioned for whom various treatments have been attempted and for whom they have had extended infection, it's been on the order of being infected for 1-2 months ... plenty of time for the virus to "cook".

The vaccines will help, if they prevent transmission as well as actually preventing the person from getting sick. The problem there is that it's entirely possible that a vaccinated person can still transmit the virus to someone else.

[Lemon Drop]

Interesting. Thanks to all for your responses. So much yet to discover.