Emily writes:

Love the show, thank you for sharing the science with the world!  I can’t even imagine how hard you all work to put out these podcasts. <3 

I get to hermit in my daily life in Idaho, but I’m flying across the country to NYC to visit my 80+ year old parents.  I wear a mask in public, and I will be wearing a well fitted N95 or equivalent mask on the plane.  

IF I am exposed and infected on the plane, how long after infection would I be considered contagious these days?  

(I received my 4th dose of Pfizer a few weeks after the bivalent became available, and have received the flu shot).  

Thank you!


Rona writes:

Dear Dr Barker,

I love watching you and your background.  I appreciate your calm backyard and how it changes with the weather.  It was atmospheric how the darkness came in towards the end of TWIV episode 968.   Speaking of the end of episode 968 it was exciting to hear that Vincent picked my “pick” recommending Columbia’s radio station WKCR.

I watch Dr Barker’s youtube of her immunology college lectures.  Thank you for making them available and for FREE! Something I hope to learn more about is the mechanism of asthma and allergies as my children suffer from these ailments.  

Episode 968 was chock full of talk of ACE2 and how coronaviruses bind to ACE2.   I was interested to hear when Dr Barker spoke about the usefulness of ACE2 in how it regulates certain necessary body functions.  

Something I was hoping you would touch upon is, is it true that asthmatics have fewer ACE2 receptors? If that is true, what do you make of the theory that asthmatics with covid generally fare better than one would have thought?  Could you discuss that theory that people with asthma have fewer ace2 receptors and this is the reason that people with asthma may not get severe complications from covid as one would have thought?



Chris writes:

What a fun episode! I have to say that your scientists are as fascinating as your science.

Astrophysics is a passion of mine and so I would love you to produce “This week in astrophysics’ with Chiara as host.

It is only because of TWiV that I am now so enamored with viruses and microbiology writ large. Viruses are far more complicated than elementary particles. I remember one of your scientists talking about how simple viruses are compared to her field of bacteria. I agree with Chiara that there is no downside to knowing more about how the universe works. Thanks to MicrobeTV I get to explore to my heart’s content.

Pulsar clocks measure ‘low frequency,’ gravity wave, 100-nanometer distortions of spacetime, over decades! Measuring the gravity wave background separately from the capture of individual wave signals – yikes! And, atomic clocks are now even better – they can measure the difference in gravity from  1 meter to the next.  I would like to ask Chiara ‘what is a graviton?’

Brian Greene once described being captured by a black hole like being caught in a river. It is kind of like not being able to swim faster than the river and getting caught. Inevitably, one goes over the waterfall or event horizon of the black hole and there is no escape. Light doesn’t bounce off the river anymore but gets caught in its flow and we can no longer see it, making it black. The only direction is down into the center, the singularity. Unless, of course, there is an Einstein-Rosen bridge wormhole.

And it’s a joy to have Angela join the family as host of TWiV and have her sister as today’s guest.

Thank you for your YouTube posts & a fabulous Sunday morning.

I just love following you in all things.

Fondest regards,


Toronto in the snow.

PS I went to Carlton University in Ottawa too but maybe before Chiara was born.

John writes:

Drs TWiV:

While watching Svante Paabo’s Nobel lecture from a couple days ago, I don’t recall mention of a correlation between a Neandertal gene and severe COVID on TWiV.

But ah!  Looking just now I see that you did this in # 676.  That was about 10 epitopes before I started following.  (Happy to hear you say NeanderTAL, too, thruout, and not THAL.)

Anyway, here it is, presented by the man himself – the COVID risk part starts about 47:00.


Best regards from Greater Braddock, where it was a typical glum November day – fully overcast and not much above freezing, except that with global warming, November is now coming in December.


Paul writes:

TWiV Panel:

Ever since I read about how important the folding of protein is I have

been amazed how mechanical the micro-world seems.  As I fumble to attach

an HDMI cable to my phone I can’t help but try to visualize a virus

trying to aim a spike at a receptor – of course in my mind this is

happening in a gooey mess.

My dumb question is how mechanical is our microbiotic system?  Does it

seem that way to you folks?


Dave writes:

Hi there TWIV team. Just saw a video by a doctor, ZDoggMD December 9 2022. Where he was talking about viral interference as being one of the possible reasons why seasonal influenza basically disappeared during the first year of COVID-19. Just wondering about your thoughts on this. You may have already covered this. 

 Dave From Wintery southern Alberta Canada. 

Barry writes:

I was just listening to TWiV 869, about EBV being a possible etiologic agent for MS. I have three important points.

I wanted to clear up a little mis-speak about HSV-1 and HSV-2. I think I heard Rich say that HSV-1 causes cold sores and HSV-2 causes genital sores. That’s a long-standing misconception in the community; both viruses cause both kinds of lesions. In fact, there are now a huge number of HSV-1 genital infections being diagnosed more and more; just see some of Ana Wald’s work. One also cannot rule out superinfection and recombination between the two viruses, which seems to be present in some patients. Regardless, the seroprevalence numbers were pretty good; HSV-1, VZV, EBV, CMV, HHV-6, and HHV-7 are each at about 60-80% of the American population (reaching 100% in the developing world), and HSV-2 & KSHV are much lower, yet sometimes as high as 50% in some groups.

I was also taken by the idea of using an existing antiviral to treat MS. MS’s constant remitting/relapsing is reminiscent of herpes infections that exit latency, then return; each acute reactivation could very well be the stimulus for a new auto-immune flare up. I’ve kept a PubMed alert alive for years, waiting for someone to try to treat MS with acyclovir or its derivatives, with standard daily suppressive therapy (EBV is susceptible to acyclovir, but it’s TK and polymerase are not as sensitive as those of the alphaherpesviruses). I have even seen a lot of literature suspecting HHV-6 as being the culprit, which means acyclovir would be useless; one would need to use (val)ganciclovir because you would need to attack the UL97-related kinase. But as mentioned on TWiV 869, it doesn’t seem that any clinician has gone out on a limb and tried any of them.

Finally, there was speculation of immunizing against EBV and its relative uselessness. On the contrary, look what we’ve been able to do with VZV, another “childhood” acquired herpesvirus. Yes, we’ve been using the attenuated Oka strain for decades (thereby creating a latent herpes infection of its own), but with the advent of Shingrix, one could easily imagine a subunit adjuvated vaccine against EBV that could work just as well at preventing MS flare ups (like Shingrix reduces the number of shingles flare ups). I do wonder if it’s only a matter of time before clinical trials are approved for the use of Shingrix in pediatric population to replace Oka as the standard of care.

Feel free to give me a shout out. I’ve known Brianne for a while now, since ASV a few years ago and more recently from our Jeopardy! appearances, and Vincent, since he gave a talk sponsored by my mentor Wade Gibson at Hopkins in the 90s. And although I left academia at the end of 2021, I’m still in the game at NIAID in Extramurals as a Scientific Review Officer in the AIDS Review Branch.


Barry Margulies, Ph.D.

Professor Emeritus of Biology, Molecular Virology

Director, Towson University Herpes Virus Lab

Department of Biological Sciences

Towson University

Joe writes:

Hi TWIV team,

I have been a big fan of TWIV and all the related podcasts since the start of COVID. You guys have been a wealth of knowledge and a calming  voice throughout the pandemic.

I am a biochemistry grad student with no virology training, so I apologize if my question is a little naïve or was answered in a previous episode of TWIV. Since the start of the SARS-CoV-2 pandemic, it seems like terms about viruses are being used very casually by the media. For example, I am still confused on the difference between species, strain, and variant when referring to a virus. In biochemistry, we often refer to a protein with a single (or a few substitutions) as a variant. Why is every new “variant” of SARS-CoV-2 a variant and now not a strain? How many mutations or substitutions does a virus have to accrue to become a new species? I am further confused when we use the term “sub-variant.” I understand what the media means by this term, but is there a formal scientific definition? It just seems like we are drawing lines in the sand on what to refer each new version of SARS-CoV-2. Why is every lineage of Omicron a sub-variant? At what point are we going to use a different Greek letter?

Thanks for everything you do- and again sorry if my question (or questions) is naïve.



Maureen writes:

Hello to the good people of TWiV. Once again, an episode connected really well with my class. To help my Virology students understand how scientists are learning about the origin of SARS CoV2, I shared the genome comparisons with Laos bat coronaviruses and revisited the term, zoonotic. I also discussed some tactics used by folks who spread conspiracy theories. I was so pleased to be able to follow up on that discussion by sharing Dan Wilson’s Debunk the Funk youtube channel. 

My students have a fun, short writing assignment at the end of each class. One option is to make a connection between the lecture topic and a personal experience. A student who works in a hospital wrote about various SARS CoV2 origin stories her patients shared, including a Bigfoot origin theory.  Her tongue in cheek question was: So, this would be considered zoonotic? 

As always, thanks for your podcast.  

Karen writes:

Dear TWiVissimi 

I found this just-published article thought-provoking and feel sure you will, too! 

“On All Fours: Transient Laborers, the Threat of Movement, and the Aftermath of Disease, ” by Tamar Novick. Bulletin of the History of Medicine, Volume 96, Number 3, Fall 2022, pp. 431-457 (Article) Published by Johns Hopkins University Press. DOI:  [ Access provided at 30 Dec 2022 23:22 GMT from Harvard Library ] https://doi.org/10.1353/bhm.2022.0035 

With continuing thanks for all that my husband and I learn from This Week in Virology and other microbe.tv podcasts — Happy 2023!



listener and supporter

[nothing to do with virology, but you might find it interesting anyway:

Karen Reeds, “Vitamin B Complexities” 

remedianetwork / H-Nutrition March 4, 2019 / [Peer reviewed]

Part of the series, ‘What Should I Eat? Why?’ commissioned by RemediaNetwork in collaboration with H-Net Nutrition by series editors Kristen Ann Ehrenberger and Lisa Haushofer. https://remedianetwork.net/2019/03/04/vitamin-b-complexities/ 

https://networks.h-net.org/h-nutrition  ]

Kevin writes:

Hi TWiV team,

Greetings from upstate!

I have consistently listened to TWiV and all other TWiX for over four years now.  Your pedantic banter, quirky enthusiasm, article deep-dives and snippets, and other intellectual interests and passions have influenced my life in very profound ways.  Your shows have kept me company on road trips; entertained me during my morning commutes during undergrad; helped me find clarity in a mess of contradictory media; taught me basic virology and immunology (and then some) in the absence of any courses; allowed me to find peace from learning about the molecular logic that allows microbial beings to dominate our macroscopic lives; and enabled me to have intelligent, founded, and empathetic conversations with many friends, family, and strangers about COVID vaccinations, treatment, and origin (all of which, statistically speaking, could have saved a handful of lives unbeknownst to me).  

So, sincerely, thank you, my friends.  In the spirit of Giving Tuesday, I’ve sent a little bit of cash to PWB to be donated to Microbe.TV.

I’m now chest-deep in my first year as a PhD student, forcing me into a new chapter as a TWiX listener.  Instead of listening to everything, I must pick-and-choose…which is a difficult reality to swallow!

I’d like to suggest two YouTube channels as listener picks.  The first is James Hoffmann  (a world-class coffee guru with frequent reviews and tutorials), and the second is Bald and Bankrupt (an unpolished world traveler and Soviet-phile).  Their abilities to communicate clearly and infectious passion for their hobbies – all told in their splendid British accents – have made their channels #2 and #3 in my favorites, just behind TWiV.  I’ve linked my two favorite videos.  I think you will enjoy them both!

Thanks again, and I hope to see you live soon!

Best wishes,