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There's nothing difficult about the two lineages at the market. What it indicates is that SARS-CoV2 had been circulating for some time before the pandemic took

by pcrh 3y ago

There's nothing difficult about the two lineages at the market. What it indicates is that SARS-CoV2 had been circulating for some time before the pandemic took off. We now know that it can spread asymptomatically. The differences between the lineages is very small, amounting to a few weeks of the same kind of random variation frequently observed in real time during the pandemic. What is does indicate is that those first diagnosed with SARS-CoV2 most likely contracted it from different sources, rather than as a consequence of encountering the same infected person or animal.

baja_blast 3y ago
And in fact the two linages only different by 2 bases, something that can occur in a single host, it in no way indicates there were two jumps. All you need is for a virus to be circulating in humans for like a week. As Stanford Biologist Michael Lim points out: >indeed he goes straight from seeing 2 lineages to concluding there were 2 jumps from wildlife days apart. That : (a) assumes the jumps were from wildlife, not people. (b) hides the fact that >2 mutations are being made in each host anyway, so separate events not needed https://twitter.com/michaelzlin/status/1632249640832880640 https://twitter.com/michaelzlin/status/1632249640832880640 >Indeed Worobey seems to think "Lineage A" and "Lineage B" are some profoundly different lineages but the tree he shows confirms they are different by only 2 bases. The "A" root has 2 fewer mutations than the "B" root. He doesn't point this out. Yet he must know. https://twitter.com/michaelzlin/status/1632249637645201408 https://twitter.com/michaelzlin/status/1632249637645201408
- pcrh 3y ago
  It isn't the fact that there are two mutations that defines two lineages. One lineage is different from the other at two positions. The mutations defining these two lineages could have occurred in either animals or humans. What it does imply is that SARS-CoV2 was circulating at the Wuhan market for at least weeks or months before the first samples were collected. However, two base changes is very little data from which to construct a phylogenetic relationship or make "molecular clock" calculations.

by pcrh 3y ago

baja_blast 3y ago

And in fact the two linages only different by 2 bases, something that can occur in a single host, it in no way indicates there were two jumps. All you need is for a virus to be circulating in humans for like a week. As Stanford Biologist Michael Lim points out: >indeed he goes straight from seeing 2 lineages to concluding there were 2 jumps from wildlife days apart. That : (a) assumes the jumps were from wildlife, not people. (b) hides the fact that >2 mutations are being made in each host anyway, so separate events not needed https://twitter.com/michaelzlin/status/1632249640832880640 https://twitter.com/michaelzlin/status/1632249640832880640 >Indeed Worobey seems to think "Lineage A" and "Lineage B" are some profoundly different lineages but the tree he shows confirms they are different by only 2 bases. The "A" root has 2 fewer mutations than the "B" root. He doesn't point this out. Yet he must know. https://twitter.com/michaelzlin/status/1632249637645201408 https://twitter.com/michaelzlin/status/1632249637645201408

pcrh 3y ago
It isn't the fact that there are two mutations that defines two lineages. One lineage is different from the other at two positions. The mutations defining these two lineages could have occurred in either animals or humans. What it does imply is that SARS-CoV2 was circulating at the Wuhan market for at least weeks or months before the first samples were collected. However, two base changes is very little data from which to construct a phylogenetic relationship or make "molecular clock" calculations.