David Quammen writes:

Vincent, I just finished listening (a little belatedly, because of drinking from the firehose) to your May 30 TWIV with Bob Garry. I spoke with him several months ago too, but your conversation was extremely valuable to me (and others) on many points, and so illuminating to our current storm of misleading articles and fuss. Thank you much. A great service. (And I agree about Amy Maxmen’s piece). Onward. High appreciation, David Q

Amal writes:

Dear twivers,

I am writing you from grey Paris, where it’s currently 28 °C and raining!

You discussed in one of the latest episodes that it’s not correct to associate mutations in the new variants of SARS-CoV2 to a better transmission, and that for flu for example, we talk about the fitness of the virus but never the transmission. I don’t quite understand clearly the difference. Isn’t better transmission mean better fitness? Although, does better fitness mean better transmission?

What does fitness exactly mean? The mutation causes the protein of the virus to be more stable? Does it mean that the virus becomes more adapted to the host (replicates more, or maybe escapes some immune responses)?

If the mutation causes the virus to replicate more and for a longer period, this means that it  would possibly increase its transmission (higher virus titers for an increased transmission time window)?

Thank you for your clarification,



Jim writes:

I’ve been a loyal listener throughout the entire pandemic. How do you respond to the discussion of the lab leak theory discussed in the Joe Rogan podcast with Krystal Ball and Saagar Enjeti? Is your hard stance against the lab leak theory due to inherent bias? Is it possible there exist to modify a virus that quickly? I really respect the objectivity of Krystal and Saagar and they seem to have at least evidence of a conspiracy to shut down any discussion of the possibility of a lab leak. I would love to hear your response as it will help drive my thinking of what really happened.

– Jim in St. Louis

Carol writes:

Hello Twivvers,

What a wonderful podcast you produce! I began listening during the early part of the pandemic and was instantly hooked. Thanks for entertaining and educating me all these months.

Your “picks” generally delight me, too. I’m a bit of a software nerd, so I was pleased by Vincent’s choice in episode 768 of Steve Gibson’s rant. The rant reminded me of the late, great Daniel Kaminsky’s comment about internet security, as related in his NY Times obituary:

“The internet was never designed to be secure,” Mr. Kaminsky recalled in a 2016 interview. “The internet was designed to move pictures of cats. We are very good at moving pictures of cats.” But, he added: “We didn’t think you’d be moving trillions of dollars onto this. What are we going to do? And here’s the answer: Some of us got to go out and fix it.”

The 2016 interview is on YouTube. Just search for “Hacker History: The Great DNS Vulnerability of 2008 by Dan Kaminsky”. Note that I am NOT sending you a link, since you don’t know me and why would you open a random link in an email? Anyway, the interview is done as a cartoon, and is one of two produced by Duo Labs. part of Duo Security (now owned by Cisco).

Thanks again for telling me all about viruses!

– Carol 

Emma writes:

Hi TWiV,

Thank you for all the great reporting you’ve done! I especially appreciate your skepticism regarding the much-hyped new variants.

This brings me to a New York Times article about the disappointing CureVac results, which suggests that the cause for the low efficacy (47% !) is likely due to variants [1].

But… it’s not the same technology! They use unmodified mRNA which has a harder time getting into cells and they use a very different sequence [2].

I’d be really interested to hear your interpretation of this result, since the temptation to blame everything on super-variants seems to preclude asking lots of interesting questions.

Best regards,

Emma from Palo Alto, where it is 93 degrees!

[1]. Article from the paper of record: https://www.nytimes.com/2021/06/16/health/curevac-vaccine.html

[2]. A random blog post my boyfriend sent me with much more information about the differences between the vaccines: https://berthub.eu/articles/posts/curevac-vaccine-and-wonders-of-biology/ 

Karen writes:


Once again, thanks so much for keeping us all updated during the pandemic. More than a year after discovering TWIV, I still listen regularly. My basic science background (MD, MPH training decades ago and two years of bench science as a research assistant before med school) doesn’t always prepare me to completely grok the science you discuss, but that doesn’t keep me from being amazed and so thankful for science and scientists. For instance, the segment on camelid antibodies was just remarkable.

I am sending you another episode from my daughter’s YouTube channel, Science IRL.   This one  (https://www.youtube.com/watch?v=sSGvk9VQQf4)  is  based on her interview with Dr. Villain Motaze, the Head of the Notifiable Medical Conditions Program of the South African National Institute of Communicable Diseases — about his team’s effort to contain spread from the first known case of SARS-CoV2 infection in SA.   

I think Dr. Motaze’s story is remarkable for (at least) three points:

1)  SA’s approach to containment was based on team visits to the homes of contacts of the first identified case  in SA (March 5,2020) for testing and for education concerning isolation to protect others from infection .  It made  me realize that I don’t remember hearing about this basic public health tool being used in US cities.  Has the US Public Health infrastructure just atrophied to the point where it is not feasible to employ this tool?

2)  Dr. Motaze, who  led the team into the field to visit people’s homes, is a medical doctor and an epidemiologist.  He did not send his team out to do this dangerous task–he led his team out.  

3)  The team performed their duties with great consideration for the people they were visiting, even though this was a dangerous and complicated task that was sometimes carried out in the middle of the night.  In order to avoid stigma for the household, they took the trouble to back their vehicle into the driveway and lifted the trunk to shield them donning their PPE and entering the house. Something about that just touched my heart.


Karen Edwards MD MPH

John writes:

Esteemed Drs TWiV:

19C and sunny here in Greater Braddock.  What I regard as like a perfect summer day in Stockholm.

At about 24:00 you commented that the au’s were epidemiologists, not evolutionary biologists or virologists.  They’re not protein chemists, either.  What I’d like to see added to a table of variants is which protein the substitution is located in, as well as what element of secondary structure in the native structure it’s in (alpha helix, beta-strand, reverse turn or random coil).  You commented that Ala–>Val isn’t much of a change, and chemically it isn’t, but Valine is beta-branched.  Going back to the old Chou-Fasman tables (which I know have been improved on but I don’t know what’s regarded as providing the best index of secondary structure potential these days), Alanine has high helical potential, while Valine with its pair of beta methyl groups is disruptive to helices.  So if the Ala in question is already in a beta-strand I suppose that a Val substitution would act to stabilize the sheet that it’s part of.  

As far as which protein the substitution is in, it seems that the ones we hear about are in the Spike.  Is that because that’s where we mostly look because of methodology?  Thinking along those lines too, if RaTG13 is the closest relative currently known, I assume that the differences are spread across the entire genome.  If so, wouldn’t that also point to SARS-CoV-2 not being engineered since something from a lab would presumably have tweaked the spike and left the parts more inert relative to infectivity alone?  Probably this point has already been made – I just don’t recall it specifically.

Nomenclature:  My first thought when the new Greek system came up was what happens when we run out of Greek letters.  How about using the same system as with hurricanes?  (Relatedly, naming vehicles after disasters and barren wildernesses – Avalanche, Tundra – doesn’t seem to have had an adverse effect on sales in that sector.  Once they got going on that they branched off into cults (Buick Enclave).  I liked it better when people drove things like Packard Caribbeans, Constellations and Panamas, Kaiser Vagabonds, Ford Galaxies and Pontiac Catalinas.  (OTOH, in the ’30s there were different series of Studebakers – President, Commander and Dictator.  Oops!  Dictator was changed to Commander in ’37 for obvious reasons.)

Best regards,


Stephen writes:

In The Atlantic:

Don’t Fall for These Lab-Leak Traps

Recent coverage of the pandemic’s origins has ensnared readers in semantic quibbles, side points, and distractions.

By Daniel Engber


Semantic quibbles, etc. seemed like an OK topic to discuss, so I began to read.

But I had to stop at this stunning false equivalency:

“The Columbia University microbiologist Vincent Racaniello said the same on his podcast, This Week in Virology: “It’s just crazy, because there’s no evidence for a lab leak; there’s plenty of evidence for the natural origin.” Others claim the exact opposite. There is “still zero evidence to support the theory that the virus emerged from nature,” Marc Thiessen announced in The Washington Post, and “mounting signs that it did not.””

According to Wikipedia: “Thiessen is a graduate of the Taft School (1985), a private prep school in Watertown, Connecticut. He earned a Bachelor of Arts degree from Vassar College in 1989 and completed graduate studies at the Naval War College.”

I’ll leave it to TWIV to compare Vincent’s bio in the relevant subjects (and note that he’s a virologist).


Martin writes:

Hi TWiV team,

You may not have heard of this story from India, where an administrator is blaming a “virulent new strain” for his own failures.

It was covered on the BBC News website (and has probably been covered elsewhere):


In short: these Muslim-inhabited islands (which I had never heard of) have a new administrator appointed by the Hindu extremist national government. Among other things, he has banned beef. He has also relaxed quarantine restrictions, so COVID cases went from zero to quite a few (figures in the article). When queried on this, he blamed a return of economic activity, but first of all (see the seventh-last paragraph of the BBC article), “the virulent new strain”.

I suspect he is not one of a kind, sadly.

Keep up the good work,

All the best,
Martin (Brussels)

Alison writes:

Hello TWIV crew!

In Chicago it is 85 degrees Fahrenheit / 29 degrees Celsius and mostly cloudy.

As a loyal TWIV listener I hear a lot of references to scientists past work with HIV. The term MSM, or men who have sex with men, is well known to all of you as a key demographic breakdown in HIV studies. Can you name a study that breaks down data by LGBTQ+ demographics? When it comes to SARS-COV-2/COVID-19 we have almost no facts on the intersections of the pandemic with SOGI individuals and communities. SOGI stands for sexual orientation and gender identity. 

I’m writing today to ask you to consider getting Microbe.TV to sign onto an open letter to Health Leaders requesting routine collection of SOGI data in health care settings. In short, the request is to have medical providers start collecting and reporting on SOGI data the same as for other demographic data like gender. I hope you can see how this work would be a contributor to your unified call for proactive pandemic, virus, and public health preparedness.

The National LGBTQI+ Health Roundtable, the National LGBT Cancer Network, GLMA (formerly the Gay and Lesbian Medical Association), The Trevor Project, and more have joined together in signing this letter in order to raise awareness that, as Vincent would say, “we just don’t have the data!” Organizational sign-ons to this letter would be a low effort, no cost way to send your patients, students, listeners, and colleagues the gift of data this Pride Month.

I am extremely appreciative in advance for your time and consideration about adding your organization to the group saying: “if you care about lives, collect the data.” 

How? Letter text and sign-on form here. Any organization welcome! 


By when? Mon Jun 21st at 5 pm ET

Then? The National LGBT Cancer Network will post it, send it to the media, and of course send you a shareable so you can promote your involvement. 

Stay safe,

Alison (she/her/hers)

Victor writes:

Dear TWiV team,

It is sweaty hot in Bonn; I do not want to know the temperature.

May I suggest a listener pick? It is a wonderful, entertaining and well-sourced video by H. Bomber Guy on the Andrew Wakefield paper that claimed the MMR vaccine caused autism.

I knew the MMR-vaccine study that started the anti-vax movement was fraudulent, but I had not realized it was such a s*** show. The video is much too long for the internet age, but each time you think it cannot get worse, there is another pile-on that demonstrates it is even worse.

Highly recommended,