Dr. Angela Rasmussen Profile picture
Oct 29, 2022 24 tweets 8 min read Read on X
The recent Senate report on COVID origins is overtly political & contains many factual errors.

Some of the most glaring are extremely basic but may not seem so to a non-virologist. As I am a virologist, I can help. Let’s talk about biosafety at WIV.

nytimes.com/2022/10/27/sci…
The report contains a lengthy section regarding biosafety lapses at WIV. It claims to show evidence of multiple biocontainment breaches.

That sounds very bad! But how reliable is this evidence?
help.senate.gov/imo/media/doc/… Image
First thing people need to know about working in biocontainment is that it’s not a “set it and forget it” mentality. You don’t build a containment lab and say, all done, let’s get to cooking up SARSr-CoV chimeras. Biosafety is a constant effort.
I work in one of the largest BSL3 labs in the world. I handle infectious SARS-CoV-2 on a near daily basis. Biosafety & biocontainment is at the front of my mind in everything I do. I have multiple colleagues whose full-time jobs are dedicated to the integrity of our lab.
There are multiple levels where biosafety protocols are implemented: all the way from individual (appropriate PPE & proper training) to the facility design & infrastructure (negative pressure, HEPA filters, waste disposal) to administrative (operational procedures, security).
Part of facility operations include regular maintenance. You make sure air handling is operating normally, the autoclaves are working, etc. Sometimes equipment breaks, so it’s replaced. Sometimes you realize there’s a better alternative, so you upgrade it.
The goal is to conduct essential research as safely as possible and constantly assessing whether that safety standard is met. If you can improve, you do—BEFORE a breach. Biosafety is about avoiding containment failures, not reacting to them.

That’s what I see in this report.
So when I see stuff like this, it seems pretty normal to me. Another key part of facility design is system redundancy. Here, WIV patented an auxiliary exhaust fan to maintain an air pressure gradient. You maintain negative air pressure in labs so pathogens can’t float out. Image
Here, WIV procured a vaporized hydrogen peroxide system to disinfect air coming from the lab. They even explain why they procured it: it’s less corrosive than an alternative. It’s an example of proactively upgrading critical equipment, not evidence of biosafety failure. Image
Same here. They were renovating the HVAC system to ensure lab air was contained in the lab. This is not evidence that any of the things they were explicitly trying to prevent (reversal of airflow, re-circulation of lab air) had ever occurred. Image
Another purchase of air decontamination equipment. Again this is a redundant system: rather than relying on filters alone, they bought a system to sterilize lab exhaust air prior to HEPA filtration. It shows there were multiple processes in place to prevent a containment breach. Image
Here WIV invented a sensor to detect HEPA filter malfunction on equipment used to transfer animals between labs. It improves function of containment measures, which again will be redundant (staff will also wear PPE, & the building itself has all the air handling stuff above). Image
And they invented a new disinfectant formulation. Liquid disinfectant is essential & we use it by the literal bucket. Many labs use Microchem, which is very effective but corrosive over time—it eventually wears out other equipment. Where can I get some less corrosive Microchem? Image
And…that’s it. No evidence of a breach or biosafety failure, but lots of evidence that they were operating a containment lab in a pretty standard way, with one exception: WIV was more innovative than many others and patented some of the bespoke systems they developed.
Which brings me to this. OMG in addition to upgrading and purchasing equipment for lab operations, they were also dealing with budget, procurement, and administrative issues, and as a result they were (gasp) MAKING POLICIES AND DOING BIOSAFETY TRAINING Image
This shows the high cost of maintenance. It’s true that BSL3/4 labs are expensive to operate (see lots of purchases above—infrastructure ain’t cheap). But here they identify this as a potential problem. Fixing problems before they cause a breach is essential to biosafety. Image
And one way to address issues of working with pathogens in substandard biocontainment is to pass laws preventing it and administratively regulate what labs can do certain research. Laws like this one. Image
And they were having a tough time getting equipment, which explains why they were so inventive. They also had meetings to remedy these shortfalls and to manage biosafety more effectively. ImageImage
And November 12, they reported that they solved a lot of these problems! Contrary to the Senate report, as well as a lot of linguistic speculation by the Chinese secrets “expert” profiled in that Vanity Fair/ProPublica piece about it, there is no mention of a biosafety failure. ImageImage
Now I’m not an expert in Chinese secrets or marginalia and I don’t speak Mandarin, but @zhihuachen has a great thread about how this report was actually just bragging to their bosses that aforementioned issues were solved, now let’s get back to safely kicking some virology ass.
I did like this part. I routinely work for 4+ hours in containment. Experiments take time. It’s not “an extreme test of will & physical endurance.” It’s a normal afternoon at work.

Burr may want to consider hardier staff, if they imagine a few hours of pipetting are so taxing. Image
And then WIV also had some biosafety training. Working in containment is “complex and grave” in that you need to be serious about biosafety & ready to respond to failures. That means you need to be properly trained. Training is ongoing & is part of how you prevent breaches. Image
And that’s it! No evidence of a biocontainment breach or a biosafety failure, other than lab leak fan fiction invented by people with no clue about how biosafety actually works reading documents that reflect the daily considerations & challenges of operating a containment lab.
Let’s hope that the bipartisan investigation which Sen. @PattyMurray said is ongoing consults experts who actually understand how operational biosafety works rather than a bunch of political science majors & Chinese secret translators.

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More from @angie_rasmussen

Dec 19
For months now, the CDC has described H5N1 as “mild” compared to prior H5N1 viruses. I disagree—the virus alone doesn’t determine pathogenicity.

I hypothesize that the 2 most critical determinants of H5N1 severity are the host (it’s always the host 🥰) & the route of infection.
The severely ill Louisiana case was infected by contact with backyard birds. In birds, influenza is gastrointestinal as well as respiratory, so contact with a lot of bird shit can cause a person to become infected.
Historically, severe H5N1 cases associated with poultry are thought to be the result of inhaling large quantities of aerosolized bird waste. The “avian” flu receptors are located in the lungs, so inhale enough virus and you get a lower tract infection and viral pneumonia.
Read 19 tweets
Dec 18
My replies are perpetually full of anti-vaxxers these days telling me about polio vaccines.

Not shockingly, most of what they are saying is wrong. Luckily, I trained with @profvrr & he taught me a few things about poliovirus.

So let’s discuss the king of the Picornaviridae👇🏻 Image
Let me start off by saying that while poliomyelitis is a terrible disease & I am anti-polio, I fucking LOVE working with poliovirus. It routinely grows to titers of 10e9 in HeLa cells & makes the clearest, most beautiful plaques even in BactoAgar that every other virus hates
Because poliovirus infects via the oral-fecal route, it can tolerate highly acidic environments like the stomach. It’s non-enveloped and virions are highly stable across a wide range of temperature & pH. You can leave PV at room temp for days with minimal reduction in titer.
Read 30 tweets
Nov 17
Highly recommend going to Bluesky to read this thread about some of the mutations found in the H5N1 virus from the patient in BC.

If you wonder what this means for pandemic risk, the answer is a very complex but unsatisfying “we don’t know”. Host adaptation is complicated.
In terms of basic technical requirements, H5N1 cannot become a pandemic virus without adapting to its host. For humans, that means adapting to different receptors, body temperature, host cell types, tissue organization, etc etc. Big changes from the avian host it’s adapted to.
There are multiple barriers a virus has to overcome to replicate in a new host:
1. Entry (and often fusion)-viruses can’t infect cells they can’t get into
2. Transcription/genome replication-gotta express viral genes and copy the genome to package inside progeny virions
Read 14 tweets
Nov 11
Thanks to the first Canada acquired H5N1 case, there’s an uptick in “bird flu pandemic imminent” and “omg it’s gone H2H!” posts. Those are not accurate.

However, given the situation in the US, I have some real concerns about this that grow progressively more grave.
First let’s get this out of the way: while a case has never occurred locally in Canada, there have been many human cases of H5N1 during this panzootic (since 2021).

It’s probably direct spillover from a bird or other animal, not human to human transmission.
But as we’ve seen in the US with dairy and poultry workers, spillover to humans will occur if there are opportunities for exposure. Right now in the US, there are many opportunities for exposure in both the dairy and poultry industries.
Read 23 tweets
Oct 24
Finally, we have H5N1 serology data from Missouri. 🙏🏻 @CDCgov.

Both the MO patient and their household contact were positive for antibodies against H5N1 in 1/3 tests. This is not definitive per WHO criteria (2 tests positive) but does suggest infection.

cnn.com/2024/10/24/hea…
Testing positive on just 1/3 tests may suggest that these patients had a transient infection. Weak seropositivity can indicate low titers of antibodies, consistent with an immune response to low levels of virus replication.
That’s good news. A more human-adapted virus would be more fit, replicating more efficiently, producing more virus, and increasing the chances of onward transmission.

This suggests that this virus isn’t very fit in a human host.
Read 6 tweets
Oct 20
When you move quickly to assess the origins of an outbreak, you can learn a lot about how it emerged just by analyzing the viral genomes.

In the case of the Marburg virus outbreak in Rwanda, it was a single zoonotic spillover from an unknown host.

Really excellent work here.
A question I have concerns the animal host. Was it R. aegyptiacus (known Marburg reservoir) or something else?

Because this “limited mutation rate” is interesting. Ebola (also a filovirus) appears to persist without replicating much as seen in outbreaks in survivors.
And if this “limited mutation rate” suggests few mutations compared to the 2014 virus (would have to actually see the data), it might indicate something similar is going on with Marburg too. Potentially in an animal host, since there haven’t been human cases in Rwanda before now.
Read 4 tweets

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