David writes:

Dear Vincent and team,

It’s been announced, this week that, variously, a new “strain”, “variant” or “clade” has been identified (VUI – 202012/01) which has been described in the “popular” press as deadly or more virulent.

Whilst, I take stories from such media as apocryphal and designed to generate heat rather than light I wondered if you could elucidate on the differences between these terms and their significance.

It strikes me that miscommunication is almost as damaging as any other aspect of this pandemic and needs to be challenged but with national leaders like the POTUS, and indeed our own PM in the UK, muddy waters run deep.

The latest mutation is reported as affecting the spike protein and, given that this is the target of various vaccines, what are the likely consequences with regard to vaccine efficacy?

I’m only a layman but, thanks to TWIV, and I hope a modicum of reason, I feel better able to counter some of the muddled thinking that I encounter on social media, not the foil hat conspiracy theorists who I fear are a lost cause, but the sort of thing generated by misunderstanding and misinterpretation of mainstream media.

Keep up the great work.


Cathy writes:

While the panel was discussing the dosing errors involved in the Sanofi trials, I began to wonder about dosing in general.  

My Questions:

  • How is it possible to dose a 100 pound female and a 300 pound male with the same efficacy if all the vials of vaccine are a standard dosage?
  • Have any trails looked at antibody response and duration in light of the standard dosage?

Many thanks!

Dominic writes:

My wife and I have watched every episode of Twiv since March because it’s the most informative, science-based source of information we’ve ever seen. Of course, we forward along your shows to spread the word too.

All of our age group are now 70 and above with many people on meds for the various age-related conditions of high blood pressure, diabetes, high cholesterol etc. Many of these folks continue to travel by car or plane, and rationalize their safety risks.

Have you ever seen any science-based studies which have documented the air flow direction, filtration methods, effectiveness and level of risk if others on the plane are infected with Covid 19. If your seat mates are shedding millions of particles, particularly without masks, say, during meal time, it seems as though those overhead air nozzles could simply be blowing the virus everywhere before the air is recirculated to the filter system. Friends are taking an 11 hour flight from MA to Hawaii to escape the high Covid numbers – sounds great if it’s safe.



I have not been able to obtain the original data to verify them.

Joe and Gina write:

Dear TWiV Stars,

It’s 28 degrees Fahrenheit, minus 2 Celsius, snowing huge gorgeous flakes here in Santa Fe, NM!

Joe and I have loved all the poems and limericks that you have read – so creative and wonderful. We thought you needed a song, so we have created “The COVID Carol” to brighten your Holidays. We were recording music for holiday concerts in our Santa Fe Theater, The Lensic, and since we had the sound and video crew set up, we took the opportunity to record this song written for all of our favorite TWiV friends. Happy Holidays to all of you, and to all of your listeners! There is hope at this season, with the vaccine already being deployed, and with the accurate scientific information that you give us in your weekly podcasts – the bright light that has kept us both sane and informed through this pandemic. It is with much gratitude that we dedicate this song to all of you!

We have included the word sheet so you can all sing with us!! (And yes, Vincent, I am a singer – an opera singer!!)

Gina (Ginna) Browning and Joe Illick


You know Vincent and Daniel and Kathy and Dickson,
Alan and Rich, Brianne and … Vixen,
But do you recall 
The most novel virus of all?
COVID, the new pandemic,
Started in a furry bat,
And if you’ve ever had it
You know it can lay you flat.
COVID-19, the illness,
comes from SARS-CoV-2
And if you want to stop it,
This is all you have to do:
Wash your hands and wear a mask
Over your mouth and nose,
Keep at least six feet apart,
You can’t get COVID from a fart,
COVID, the new pandemic,
Started in a furry bat,
If we all work together,
We can lay the virus flat!
Happy Holidays to all,
Staying safe at home,
Sharing love and joy and cheer,
Then we’ll be together next year!
If we all help each other,
While we get the new vaccine,
We’ll let go of 2020,
And say good-bye to COVID-19.

Danika writes:

Hello to all the TWIV Avengers!

Yes, Avengers is how I view you all – Avengers assembling weekly to battle misinformation and protect the world with truth and science!

I do have a question for you all, and I’m not certain which TWIV Superhero is best fit to answer.

My question is about herd immunity. From what I understand, we do not have any evidence that the vaccines protect COVID-19 from spreading to other people – we only have data on efficacy for the recipient. Certainly, absence of evidence is not evidence of absence, however, if we find this to be true – that the vaccines only prevent the vaccine recipient from illness, but viral shedding still exists at a level that can cause infection in others – it seems that vaccines might not be the herd-immunity answer we have all (including Dr. Fauci) been touting. Put another way, mass vaccination would not prevent an illness from spreading or getting established in a society – just prevent massive rates of illness….which isn’t really herd immunity.

So my questions: Is touting herd immunity premature? Or can we reasonably assume that mass vaccination, even with viral shedding, can achieve herd immunity? Or can we reasonably assume that viral shedding does not happen based on what we know with other vaccines? Am I misunderstanding how herd immunity works? I welcome all of your thoughts on this!

I think this question does relate to how we communicate about the vaccine. The “vaccines are not just about protecting yourself, it’s also about your community” really seems to only hold water if vaccination prevents infectious shedding.

If this question has already been discussed, please let me know which episode and I will make sure to listen! I’m a regular listener, but also recognize that I might miss some important discussions and topics.

Thank you,


Bellingham, Washington

Epidemiology Graduate Student who JUST finished my finals and is stoked to get caught up on all my podcasts!

Andrew writes:

Hi Vincent

I trained at NY Hospital in the 1980s, so maybe we even passed each other at the PK!

In case you didn’t catch this, an EUA was granted today for the first OTC fully at-home diagnostic test for SARS-CoV-2:


“Today, the U.S. Food and Drug Administration issued an emergency use authorization (EUA) for the first over-the-counter (OTC) fully at-home diagnostic test for COVID-19. The Ellume COVID-19 Home Test is a rapid, lateral flow antigen test, a type of test that runs a liquid sample along a surface with reactive molecules. The test detects fragments of proteins of the SARS-CoV-2 virus from a nasal swab sample from any individual 2 years of age or older.”

Will be interested in hearing the TWIV team and Michael Mina’s take on this news.

All the best,


Andrew Farb, M.D.
Chief Medical Officer, Office of Cardiovascular Devices (OHT-2)
Center for Devices and Radiological Health (CDRH)
U.S. Food and Drug Administration

Erin writes:

Good morning! 

There’s an FDR quote “When you reach the end of your rope, tie a knot and hang on.” 

Your thoughtful, patient and wise voices have been my knot.  Rich Condit’s gentle boom and Brianne Barker’s clear diplomacy,  Vincent’s salty crackle that cares…. and Daniel’s direct dispatches from the frontlines…  all of you combine to bring me a sense of peace and trust that we are in the good, capable and dedicated hands of experience even when the chaos of Washington seems otherwise.  Thank you.  

You have also been kind to answer a question from me a time or two, and now, I hope you might answer one from my 5th grader. 

He was thrilled to hear that we have a vaccine, dampened slightly by realizing that manufacture and distribution will take time, but positively crestfallen that kids aren’t “on the list.”  He wants to understand  when and how the phases of development will happen for kids. 

(He is ready to have sports, sleepovers, socializing, travel and all the hugs back, aren’t we all!)  

Thank you as always for your guidance-

A mom in Texas

Sent with love. 😍

“It takes two to make a thing go right …. 🎤

see https://www.theguardian.com/commentisfree/2020/dec/18/when-can-children-get-the-vaccine-five-questions-parents-are-asking

Justin writes:


I made a YouTube about our small, rural EMS agency getting the Pfizer vaccine. Here’s the video: https://youtu.be/RWd3T-DiTq4

If you think it is useful or sharable, please share it on your platforms!

Your show has carried our family through the pandemic, thank you!

Justin Porter 
Aero Methow Rescue 
RWJF Clinical Scholar

Lori writes:

I really have enjoyed TWIV and the great information you are discussing. I am hoping to take advantage of the holiday season to mobilize an onsite COVID rapid testing for my son’s high school. Now that there will be over the counter testing available, I believe we could have a High School organized to get the kids to do the tests, interpret them, document, record and report results. I have tried to involve the bureaucracies (government, education, health) and I am not sure they will help, but let’s assume I can get this going.  Can you tell me what test you recommend for this and is there anyone that knows how to order these in bulk. Studies I have read recently suggest all teachers and students tested every 2 weeks can adequately keep our environment safe and kids in school. 

Thanks for any input. 


Anne writes:

Dear TWIVvers,

Like another of your listeners, I’m in a Regeneron clinical trial where four subcutaneous shots of the antibody “cocktail” are given sub-q monthly for 6 months to healthy people. I’ve gotten 3 sets of shots so far. I’m 70 and at the site I go to, the injections are typically two in the abdomen and two in the thigh. 75% get the antibodies and 25% get a placebo; I have no idea which I am getting.

With the vaccines coming out, I might contemplate dropping out at some point to get a vaccine, especially as the trial continues 6 months past the administration of all shots to continue blood draws and such. But if I do, I have a dilemma that I hope TWIVvers could help me with.

I have to assume I’m getting the real thing, and, if I am, from what I understand I’d want to wait for a period lest the Regeneron antibodies interfere with the effectiveness of a vaccine. But, for how long should I wait?

I assume it depends in part on the half-life of the antibodies but I’ve been unable to figure out how long that is likely to be? And once I know, how long do I wait? One half-life? Two half-lives? 

Any thoughts or help from the TWIVvers will be much appreciated.


Austin, Texas

Scott writes:

Greetings TWIV Team:

While I understand the definition of infection and disease with respect to the SARS-CoV-2 virus and COVID-19, I do not really understand how someone who is vaccinated can shed virus and infect other people.

It seems to me that if you are vaccinated your body should be able to stop the replication of the virus and prevent it from spreading to other people, but it clearly is not so.  So, I guess I would like to better understand how one can be infected and shed virus, but not have it cascade into disease / sickness.  Could you potentially elaborate on this?



Menomonee Falls, WI where it is cloudy and below 0C these days….

Maureen writes:

I love your show! In med school Immunology was my favorite basic science but my life work was in Family Medicine. Now I’m retired but fascinated w COVID. 

I heard last week that herd immunity is not possible with m-RNA vaccines because they only prevent disease not infection or transmission. So we need a hundred percent immunization for all to be protected. 

Tonight I heard Dr David Kessler on the news mention possible herd immunity at 75% vaccinated. 

So which is it? Does the vaccine prevent infection and transmission or just disease? (Maybe I misunderstood). 

Please explain on your show. You may have today but I haven’t listened yet. 

Thank you do much. 

Maureen Longworth, MD

Juneau, Alaska

Sara writes:

Thank you so much for all of your guys’ work. I’m one of the newbies who started listening in January 2020 but i can not express enough how incredible it has been to be so informed during this pandemic. I even love it when I hear terms and processes that I don’t understand, there’s something very reassuring about it. I wanted to ask if you had the choice between the Pfizer vaccine and the Moderna Vaccine which would you choose and why? 


• Provider and Community Outreach Specialist

• El Centro Regional Medical Center