4 ms·

It's not circumstantial evidence in the case of the market, there is direct evidence. You're ignoring the fact that contact tracing of early cases pointed to em

It's not circumstantial evidence in the case of the market, there is direct evidence. You're ignoring the fact that contact tracing of early cases pointed to employees of the market and people who visited the market, and that SARS-CoV-2 was found in environmental samples from the market. On the other hand, there is no contact tracing and no biological sample that leads to the WIV or its employees.

tripletao 3y ago
There's no question that the market was a major cluster, but that doesn't mean it was necessarily the point of introduction. SARS-CoV-2 must have been introduced to other continents at airports or seaports, but that's not where the first major clusters were found there. SARS-CoV-2 has relatively low IFR, and symptoms easily confused with other respiratory illnesses. This means that even with advance warning and good surveillance, many generations of cryptic spread are possible before someone gets sick enough to get tested. I've seen many fine-grained geographic arguments, both for and against unnatural origin, but would generally consider them to be noise given that early under-ascertainment. As to the environmental samples, virus was definitely present in the market, since infected humans were present. A few samples with raccoon dog DNA were found with a few SARS-CoV-2 reads; but almost all the SARS-CoV-2 in that market must have come from infected humans, and there's no evidence those reads didn't too. The correlation between SARS-CoV-2 presence and raccoon dog presence is negative, and that correlation is most positive for non-susceptible animal species; so I again think that's noise. This is from Jesse Bloom's analysis at https://www.biorxiv.org/content/10.1101/2023.04.25.538336v1 https://www.biorxiv.org/content/10.1101/2023.04.25.538336v1
toomim 3y ago
That's direct evidence that covid was in the market, but only circumstantial evidence for where it originated. The market was both (1) close to the lab and (2) a place where nature contacts humans. The lab origin theory says it originated in the lab, and then an infected WIV employee came to the market for lunch or dinner and created a super-spreader. The zoonotic theory says an animal brought it or a precursor to the market, where it possibly mutated and jumped to humans. The existence of covid in the market provides circumstantial evidence for both theories.

tripletao 3y ago

There's no question that the market was a major cluster, but that doesn't mean it was necessarily the point of introduction. SARS-CoV-2 must have been introduced to other continents at airports or seaports, but that's not where the first major clusters were found there. SARS-CoV-2 has relatively low IFR, and symptoms easily confused with other respiratory illnesses. This means that even with advance warning and good surveillance, many generations of cryptic spread are possible before someone gets sick enough to get tested. I've seen many fine-grained geographic arguments, both for and against unnatural origin, but would generally consider them to be noise given that early under-ascertainment. As to the environmental samples, virus was definitely present in the market, since infected humans were present. A few samples with raccoon dog DNA were found with a few SARS-CoV-2 reads; but almost all the SARS-CoV-2 in that market must have come from infected humans, and there's no evidence those reads didn't too. The correlation between SARS-CoV-2 presence and raccoon dog presence is negative, and that correlation is most positive for non-susceptible animal species; so I again think that's noise. This is from Jesse Bloom's analysis at https://www.biorxiv.org/content/10.1101/2023.04.25.538336v1 https://www.biorxiv.org/content/10.1101/2023.04.25.538336v1

toomim 3y ago

That's direct evidence that covid was in the market, but only circumstantial evidence for where it originated. The market was both (1) close to the lab and (2) a place where nature contacts humans. The lab origin theory says it originated in the lab, and then an infected WIV employee came to the market for lunch or dinner and created a super-spreader. The zoonotic theory says an animal brought it or a precursor to the market, where it possibly mutated and jumped to humans. The existence of covid in the market provides circumstantial evidence for both theories.