Not many read the Chinese CDC's manuscript which was the source of data used by the Proximal Origin group in their recent reports. The market had 678 stalls with a space of >50,000m2, located ~800m from a major rail hub and in a downtown district. assets.researchsquare.com/files/rs-13703…

@Craigmck5 @flodebarre Its retail space was covered the area of 40 Olympic swimming pools. This was not a small market.

Nonetheless, it's nonsensical to use ratios of genetic material from a surface sample - especially one that has been processed so that non-viral material is lost - to infer the host species that shed the virus into the environment.

I was initially mistaken in thinking that a whole genome or exome enrichment kit had been used to pull off human genetic material from the samples. It's more likely that an enrichment kit was used to pull down virus genetic material.

A test of the weakness of any given piece of evidence is how easily you can explain it away if definitive evidence for a lab leak emerges. So far, all of the so-called strong, dispositive evidence can be readily explained away as due to a human superspreader event at the market.

So I'm surprised that everyone is so shocked three years later to hear that there was raccoon dog genetic material at a stall known to have sold these animals.

This is what the world was told in January 2020 by the Chinese authorities: “The origin of the new coronavirus is the wildlife sold illegally in a Wuhan seafood market,” Gao Fu, director of China Center for Disease Control and Prevention, told a briefing. reuters.com/article/us-chi…

World Health Organization correctly assessed the meaning of the new data: "What the data do show is molecular evidence that animals were sold at the market and some animals there were susceptible to SARS-CoV-2, said the WHO's COVID technical lead"

@erikbiz Best breakdown so far: academic.oup.com/mbe/article/38…

Notably, in order to explain why all the Dec 2019 market cases were only infected with Lineage B of the virus, the Proximal Origin group had to push the 1st spillover as happening only on 18 Nov 2019. If non-market cases in Nov are found, their hypothesis will be obliterated.

Not evidence of infected animals/animal source of the virus: 1. Animals present at the market 2. Early cluster of cases at the market Both facts known in early 2020 and consistent with human superspreader event at the market.

Examples of evidence of infected animals/animal source of the virus: 1. Infected animals at market or supply chain 2. Animal variants of the virus 3. Serological evidence that the animal traders had been exposed to SARS2-like viruses before the pandemic

Recall in 2020 when the virus was found on a chopping board for imported salmon at a Beijing market. If you sampled the chopping board, would you find more human or fish genetic material? Would that tell you if it was the 🧍 or 🐟 that shed the virus? bbc.com/news/world-asi…

Considering that it is a surface and not an animal that is being sampled, contaminating genetic material cannot be used to determine the host that shed the virus. There is nothing in the sequencing data that says the virus came from a human or a raccoon dog.

The presence of animal genetic material sampled from surfaces at the Wuhan market in Jan 2020 doesn't tell us: 1. If there were live animals in Nov/Dec 2019. 2. How many there were, if present. 3. If the animals were infected with the virus.

Desperation is inferring the existence of an infected animal at the market from the presence of animal genetic material at the market, which had been plastered with virus across its >9 NFL field-sized retail space. #OriginOfCovid twitter.com/jbloom_lab/sta…

@michaelzlin @JamieMetzl This really strikes me a twitter thing. I've talked with many scientists (in real life) about Covid origins, and there were exactly two who expressed 'high confidence' in a zoonotic spillover scenario. Most remain largely agnostic, and the more knowledgeable, often the more so.

Analyses of Jan 2020 samples is definitely worthwhile, because as @DrTedros rightly noted each piece of data is important for better understanding initial outbreak in Wuhan. But to identify actual origin of outbreak, we need details from Nov or early Dec 2019.

@Hyper_Number @stuartjdneil There are kits where a library of probes specific to what you're trying to enrich/remove are used. I can't say I know which kit the CCDC used but their wording is that "human nucleic acid was removed using an enrichment kit".

@wanderer_jasnah Whole genome/exome kits exist where you pull down human nucleic acids. There's no reason why one could not specifically remove human nucleic acids using such an enrichment kit. But I agree, without know what kit was used, it will be challenging to tell if it was species specific.

Nonetheless, you cannot infer host by the abundance of reads in a surface sample. We don't know what was on the surface that was swabbed. Was a slab of raccoon dog meat on the table before it was swabbed? twitter.com/Ayjchan/status…

I'm not saying that I believe all data available to #OriginOfCovid has been shared. But if you're going to use the data provided by the Chinese CDC, you should at least pay attention to the methods by which they collected that data.

@flodebarre Happy to discuss directly at this Twitter Space tonight but the time is very late for you in Europe. twitter.com/jbkinney/statu…

@flodebarre (De)enrichment kits are never 100% effective. You'd still see some human material. What is important here is that you cannot interpret the ratio of human:non-human material.

@KierenLythgow Please see: ayjchan.medium.com/evidence-for-a…

I’ll be discussing this past week’s raccoon dog news and the recent preprint at @BiosafetyNow’s upcoming Space tonight at 8p ET. twitter.com/i/spaces/1Mnxn…

One can only hope that the scientific journal reviewing the Chinese CDC paper will finally let them publish so we can see if more complete datasets and methodology are available. Even better if the peer review process can be made open so people can see what the hold up was about.

Finding more fish on the virus-plastered surfaces of the stall doesn't mean that the salmon gave your fishmonger covid. The scientists who wrote up the new report admit this: twitter.com/scotub/status/…

Official statement:

If you swab the equipment, tables, floors, and walls at the stall of your local fishmonger who was ill with covid, would you be surprised to find virus-positive surface samples contaminated with more fish than human material?