Oh great, Alex Wasburne again. His preprint paper (still not published) was just awfull, and we went over this in detail years ago. You were there too.
Of exactly what? Geographical clustering of early cases? Then this is false. The Huanan Seafood Wholesale Market in Wuhan was the early epicenter of the COVID-19 pandemic.
Even if we were to do this right at the time of the outbreak, this wouldn’t do much good either since MOST animal traders and their stuff would be tested negative too. You would only do this if you expected that most animals (of the suspected species) that are traded would be infected with the virus you are looking for, but this would not be the case.
What you would do is testing suspected individuals at the location of the outbreak. This is how they identified infected palm civets at a wet market within 4 months after the SARS1 outbreak in 2003. But they were able to do this since the market continued to operate like normal, selling living animals. This is different from our situation where the Chinese Government promptly shut down and sanitized the wet market, with all the animals were culled and disposed (except for a few frozen animals). This is similarly true for all the wildlife farms nearby. It’s thus not surprising that we did not find a living animal infected with SARS2. (See discussion by Paull Offit for more). And SARS2 is not alone in this regard too. The animal origins of Ebola, Hepatitis C, Polio, and even other human coronaviruses (HCoV-HKU1 and HCoV-NL63) are not identified (see discussion here). It also took 14 years after SARS1 outbreak to identify reservoirs in bat populations with >95% similar viruses. In short, next to no animals were available to test. Hence ‘absence of evidence ≠ evidence against’ in this case.
Having said that, we do have environmental samples from the wet market. Some studies that discuss this include here and here.
The reservoir is not necessarily at the location of the outbreak. Again, this is also true for SARS1 as well as SARS2. Both reservoirs are located over a thousand kilometers away from the sites of their respective outbreaks. Details discussed in this recent paper.
Ah, an old argument. While not found among the closest relatives of SARS2, Furin cleavage sites are nonetheless found among betacoronaviruses, and have evolved multiple times within this group. This also includes those that cause the common cold in us, such as HCoV-HKU1 for which (as previously mentioned) we have not identified the animal source. Humans are the only known reservoir of HCoV-HKU1. So it’s not out of the question that SARS2 could’ve evolved an FCS as well. (For more see here, here, here, and here)