Why is ‘lab leak theory’ still considered as possible?
So right off the bat I understand that this is just how science is written, confidence is always hedged out of need for caution and precision. It just appears to me that we have sufficient research to rule it out to a degree in which entertaining it at all feels a bit absurd.
For context, I thought up until very recently that there was enough room for some reasonable doubt in zoonotic origin even though it was more likely the explanation than a lab leak. Then, while debating someone who favored lab leak, I started catching up on some studies from just the past 2-3 years and realized how far behind I was.
This study in particular really put it all together for me in a way where I could no longer conceive of a way in which the alleged cover ups or a lab made source could ever explain all these studies when placed together:
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>Multiple lines of evidence are consistent with the infection of wildlife animals with SARS-CoV-2 in the Huanan market. Animal carts, a cage, a garbage cart, and a hair/feather removal machine from a wildlife stall tested positive for SARS-CoV-2, and there was more DNA from mammalian wildlife species in these samples than human DNA. The surrounding stalls also had relatively higher rates of SARS-CoV-2 positivity, and drains adjacent to and downstream of this wildlife stall tested positive for SARS-CoV-2. Finally, there were several other viruses known to infect wildlife in these samples. These data indicate either that the animals present at this stall shed the SARS-CoV-2 detected on the animal equipment or that early unreported human case(s) of COVID-19 shed virus in the exact same location as the detected animals. Under a zoonotic scenario, viral shedding by infected animal handlers is expected to occur after shedding by the animals they were infected by. Therefore, human viral shedding post-zoonosis could plausibly also explain these data; in such a case, the animals brought into the stall are therefore still the most likely candidates for the zoonotic source. Although either animal or human viral shedding is consistent with these data, only a zoonotic origin of SARS-CoV-2 directly predicts co-detection of SARS-CoV-2 and wildlife genetic material.
>It has been proposed that humans could have introduced the virus into the Huanan market.^(25)^(,)^(57) It is most likely that there were human infections of SARS-CoV-2 earlier than the first documented and hospitalized market cases, including unascertained market cases or contacts thereof. However, the detection of lineage B and lineage A both within and indirectly (geographically) linked to the Huanan market implies that SARS-CoV-2 most likely emerged there or its supply chain before the tMRCA, by which time there would have been an estimated median of just three people infected (95% HPD, 1–18).^(11) Any hypothesis of COVID-19’s emergence has to explain how the virus arrived at one of only four documented live wildlife markets in a city of Wuhan’s size at a time when so few humans were infected.^(3) Human introductions linked to the animal trade offer one explanation for this, and the introduction of the virus by an animal trader or farmer cannot be excluded, but these hypotheses are challenged by phylodynamic evidence for multiple spillovers.^(11) The introduction by an animal trader infected by animals upstream of the market is further challenged by the probability that transmission chains dependent upon a single human would likely go extinct,^(17) while a sustained interface between infected animals and humans in a market is more likely to result in the establishment of an epidemic.
I am not a geneticist, I took a few course as part of my major but that was years ago. Am I missing something though? Is there a flaw in the methodology of any of these studies I’m not seeing? Have I just fundamentally misunderstood what I have read? Or are communicators being far too charitable in messaging about how confident we can be about the origin?