Alina Chan Profile picture
21 Feb, 25 tweets, 9 min read
Before the WHO-convened global study on the #OriginsofCovid releases their interim report this week (maybe), I think it's useful to explain to the public where all the evidence lies right now across the 4 hypotheses presented by the origins team…
For the sake of simplicity, hypotheses 1 and 2 can be combined into scenario A, which includes virus transmission from the animal reservoir (most likely bats) directly into humans or through an intermediary animal host that is more closely related to humans.
The WHO-convened team stated that cold chain supply (scenario F) is an #originsofcovid hypothesis deserving of follow-up.
Importantly @Peterfoodsafety later clarified they are only considering within-China cold chain food trade, not from outside China.
Lab origins can be divided into several distinct scenarios requiring different methods of detection & investigation.

Scenarios B, C, and even D likely do not produce a virus with detectable signs of lab manipulation. In other words, viruses emerging B/C/D can look 100% natural.
Sometimes even major engineering (scenario E) can slip pass detection of lab manipulation. The current approaches can only find what they're looking for. If you don't know what's in your opponent's tool kit, you very likely can't detect their signatures.…
Viruses escaping from labs can span a wide range of fitness and host preference. They could be well adapted for binding and using receptors in human and other lab animals (scenarios B, C, and D), especially if sampled from localized human outbreaks in isolated rural areas...
... or they could be "fresh" from nature (scenario B).

imo scenarios A and B need to be separated even though both involve animal-to-human transmission outside of a lab, because the route of investigation and the prevention responses are entirely distinct.
The investigation of scenario A is driving hundreds of research personnel or hired hands to sample tens of thousands of wild animals (including bats) and search for localized outbreaks in humans- this is essentially the set up of scenario B, which could risk pathogen emergence.
So where does all the existing evidence sit?
The table is self-explanatory. In summary, there are precedents for both natural & lab-related outbreaks of SARS. No direct evidence reported for any of the hypotheses. Location suggests a lab origin due to distance from SARS spillover zone and proximity of a major SARS lab.
If there are going to be likelihood estimates - at this stage where so much is still unknown - in the WHO-convened #originsofcovid team's report, these estimates should ideally be supported by a substantial analysis of primary (non-aggregated) data relating to each scenario.
I understand that there are likely many interfaces in Wuhan where humans are exposed to live animals, some transported from far away in China. But what are the @WHO team's estimates of the exposure to research-based collection and study of pathogens?
It's difficult to guess how likely lab origins is considering we don't know how many trips from Wuhan were made (and where) to collect pathogens from animals or humans (scenario B), and how many SARS viruses were collected, sequenced, produced, otherwise studied (scenarios C-E).
We know about cases of mysterious pneumonia, described to be SARS-like, among miners in Mojiang, Yunnan, China in 2012. Important pathogen labs in China, including WIV, followed up & found SARS2-like viruses over the years, but how many other under-reported outbreaks were there?
Unfortunately, several countries do not follow the International Health Regulations (IHR).

Even in the case of the COVID-19 pandemic itself, the World Health Assembly has directed the WHO to evaluate whether IHR were adhered to.…
I hope that it isn't controversial that, in order to estimate the likelihood of lab origins, it is necessary to first get the actual numbers, as much as is possible, describing the extent of sampling from wildlife and humans suspected to carry pathogens over the past decade.
When the interim report does get published, I hope that this table can be useful to anyone trying to understand whether the WHO-convened team was able to access the data/evidence required to inform likelihood estimates for each #OriginsofCOVID hypothesis.
If any expert uses language like "a ton of evidence" "overwhelming evidence" "scientific consensus" points to X hypothesis, whether natural spillover, lab origins or #PopsicleOrigins please challenge them on the exact type of evidence they're talking about. Is it just precedents?
Or is it their gut feeling, based on past experience, that there should be a ton of evidence pointing at their hypothesis of choice?
One strange argument I’ve seen is “SARS2 could’ve emerged naturally so that = evidence against/inconsistent with lab origins.”

I don’t think this is logical. That’s like saying a person could’ve driven to point X via route A so that = evidence inconsistent with route B.
In the absence of any direct evidence, the plausibility of one origin doesn’t shoot down the plausibility of other origins. For example, if cold chain origins are shown to be plausible, that doesn’t mean that specific evidence is against or inconsistent with non-frozen origins.
Because the investigation into #OriginsofCOVID is necessarily forensic in nature, any newly revealed intelligence or piece of direct evidence can dramatically change the likelihoods of each of the 4 hypotheses considered by the WHO-convened team.
And I believe that some intelligence already exists, although still classified, which circumstantially point towards lab origins.

Again, just because some evidence may suggest lab origins, does not = against or inconsistent with natural origins.

More on the previous @StateDept Facts Sheet and the intelligence on the #originsofcovid Start watching at 14:18 min mark.…
fyi I have not seen any of this intelligence but the former deputy national security adviser says...…

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More from @Ayjchan

22 Feb
One fact that I think many scientists and members of the public are not widely aware of is that the original SARS virus - back when it was the only SARS virus known to man - escaped from labs not once but 4 times.

2 of those times from a top Beijing lab.…
For those lab escapes of SARS1, "once the alarm was raised about the cases, over 1000 of their close contacts were isolated very quickly"

But would this have stopped a virus like SARS2 that can spread asymptomatically with up to 2 weeks incubation time?…
In 2004, SARS was the only SARS virus studied in labs - 4 lab escapes.

Fast forward to 2019, there are several dozens (likely 100s) of SARS-like viruses sampled by labs.

After covid, a whole bunch of SARS2-like viruses collected in the past get published.
Read 10 tweets
19 Feb
“Chinese authorities declined to give the WHO team raw data on these cases and potential earlier ones”

Data they saw “could possibly indicate infections as far back as September, said Marion Koopmans, a Dutch virologist on the WHO team.”…
🌟 by @LawrenceGostin
“Sovereign states will almost certainly resist IPPPR proposals to empower the WHO to enter their territory and gain access to full information.. (eg) inspectorate system like the ones currently in nuclear nonproliferation treaties.”…
The @WHO origins study shows us serious problems in pandemic reporting & tracking. Tho much data exists & more could’ve been found a yr ago, no world organization was granted the power to access and collect such data.

As a result, the world doesn’t even know when covid started.
Read 5 tweets
18 Feb
We can credit the @WHO coordinated exploration with some things: They got into China after 1 year. They got to see what their Chinese counterparts had prepared for them, itinerary and reports. They got to see what their Chinese counterparts would not share with them or answer...
What I would like is if the team can carefully lay out: What they asked. What answers/data they were given or not given. Their hourly itinerary, who was in attendance at each event/meeting, if there was voting (and if there were non-unanimous votes; just numbers, not identity)...
I understand that a summary, full report & pressers are coming but these have to be signed off by ALL members including 50% of the team who are scientists in China.

Can journalists talk to non-Chinese teammates w/o disclosing their identities to get a handle on what happened?
Read 9 tweets
18 Feb
Some scientists expected this day would come but somehow it's still annoying that it's gotten to a stage where some individuals are infected by 2 or more separate people/events, sometimes resulting in recombination between different SARS2 variants.…
On this topic, one major challenge is getting these new data (raw or assembled genomes) onto public databases ASAP.

I think there's some competition happening among the top databases. This has to stop for the duration of the pandemic. Priority is getting data public ASAP.
It can't be a situation where scientists and developers of vaccines, therapeutics, and diagnostics are learning about new variants from @TheScientistLLC @CNN etc.

Scientists need to have access to these data ASAP so we can optimize all the tools we have to fight this pandemic.
Read 6 tweets
17 Feb
Really good piece in ⁦@NBCNews⁩ by ⁦@KenDilanianNBC⁩ et al.

Questions about how large the covid outbreak was in Wuhan, how early it could’ve started, maybe even Sep 2019 if there were already dozens of unconnected cases in October..…
Extremely challenging to answer these questions without access to thousands of banked patient samples from Wuhan from fall 2019, and the actual non-aggregated patient records from that time. Not just the 90+ shortlist but thousands of people with pneumonia in Wuhan fall 2019.
Office of Director of National Intelligence: agency "will continue to rigorously examine emerging information.. to determine whether the outbreak began through contact with infected animals or if it was the result of an accident at a laboratory in Wuhan"…
Read 6 tweets
16 Feb
On to my more contentious 🧵 of the night.

“It’s very funny that everyone is worrying about preprints given that, collectively, journals are not doing a great job of keeping misinformation out,” Sever (co-founder of medRxiv and bioRxiv) said.…
There's been a lot of criticism of preprints since COVID-19 appeared. I've done my fair share too, breaking down preprints (and mostly peer-reviewed articles).

But I think the misinformation tragedy lies in peer-reviewed journals, NOT preprints.
"In the academic world, the Center for Health Security at Johns Hopkins issued a point-by-point response one week after Yan’s paper appeared on Zenodo"

Why didn't John Hopkins do a point-by-points response to RaTG13 or the #pangolinpapers?
Read 12 tweets

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