Adrianna and Liem write:

Dear TWiV team,

We are researchers at the University of Melbourne studying antimicrobial resistance in hospital pathogens and have greatly enjoyed listening to you in the lab over the past few months. Your podcast makes experiments involving a lot of repetitive pipetting far more enjoyable! We have recently experienced a “second wave” here in (moderately sunny 16C) Melbourne, but an extremely strict lockdown has brought COVID-19 cases down relatively quickly (from ~750/day to ~20/day in 5 weeks). 

We are not virologists or immunologists by trade, but both agree we have learned a great deal from listening to TWiV! In previous episodes you have stated that people with low viral loads are less likely to transmit SARS-CoV-2 from person to person; an assumption that forms the basis for the “Mina testing plan”. You have also discussed that based on observations of reinfection by SARS-CoV-2, and given what we know about immunity to seasonal coronaviruses, a vaccine against SARS-CoV-2 seems likely to provide protective (rather than sterilising) immunity, which may mean that vaccinated individuals can still spread the virus. The implications of this scenario are important, as such a vaccine may not protect people who can’t/won’t be immunised, or groups for which the vaccine is not efficacious.

Our questions are; 

With what certainty can you state “a non-sterilising vaccine will not reduce spread”? 

Is there evidence that other protective vaccines reduce viral load and therefore transmission rates? 

Could such a vaccine help reduce the frequency of “super-spreader” events? 

Could a protective vaccine, administered to enough of the population, lower the R0 and help manage the pandemic? 

Thanks so much for TWiV, we have become evangelists for your podcast and will continue to recommend it far and wide!

All the best,

Adrianna and Liam

Adrianna Turner

PhD Student | Howden Lab

Department of Microbiology and Immunology

The Doherty Institute for Infection and Immunity

The University of Melbourne, Victoria 3010 Australia

Charles writes:

Limerick (I don’t think I broke any rules):

Informed Trump, Knew The Truth, Deadly Virus.
Miracle Hope, From A Dope, Lied To Us.
We Must Now, Remove The Dolt.
So Get Out, And Go Vote.
Do It Now, No Delay, Protect Us.

Quote from Senator Daniel Patrick Moynihan:

“You are entitled to your opinion. But you are not entitled to your own facts.”

TWiV arcs:

I am just a computer programmer.

53F, 12C, in Chapel Hill, great walk at Brumley Forest.

Looks like the media needs a lesson about the difference between CFR and IFR.  On TWiV 665 it sounded like Rachel Maddow or her guest got it wrong.  About a week ago Philip Bump at the Washington Post got it wrong.  Link to Bump’s article:

The comment by _PLCF_ is mine.

I am not an epidemiologist, which means I am about as qualified as Scott Atlas (Trump’s new BFF for all things COVID-19) to calculate how many deaths will be caused by going for herd immunity.  I would like for the TWiVers to judge if I got it right.  Here goes.  First my assumptions: US population 328,239,523, IFR 0.68% and 91% infection rate.  The math is simple:  328,239,523 * 0.0068 * 0.91 = 2,031,146 deaths.  I don’t think anybody will argue with the population.  Some may argue with the IFR, but not by much.  The infection rate could be a problem.  I don’t think that herd immunity works for a virus that we do not develop a durable immunity to.  From listening to TWiV 665, if I understood correctly, you agree that herd immunity for SARS-CoV-2 is not the correct measure.  Going for the lowest infection rate of the common cold corona viruses seems like a better estimate.

So did I get it right?

Links for assumptions:



Infection rate:

91% was the infection rate for HcoV-HKU, the lowest of the 4 common cold corona viruses.



Anonymous writes:

Legal right wing nut job pseudovirology

The key to exposing these things is the fact that they pick a narrative and select the supporting evidence to proffer.  

This reminds me of the HIV stuff that came out in the late 90s.  I can’t recall the name, but there was publication from England geared at HIV health and a Greek woman virologist -papadopolis or something like that – writing up articles in this,  pontificating this garbage to allege that Luc Montagnier and Gallo and all the HIV research virologists were building everything based on a house of cards, and the DNA chain terminators – nucleoside analogs were iatrogenic  and the cause of AIDS. 

It went deep and deceptive.   I lost a friend that embraced this, as did the publisher I’m sure. 

Thank you for breaking this down.   It’s almost like you don’t want to give it Oxygen but, it needs to have sunlight shone upon it, so that the filth can be seen floating about. 

Kim writes:

Twiv team,

Thank you TWIV for providing me a scientific escape a few times a week from the reality show type news cycle. I discovered your podcast on long drives this summer to camp, hike, mountain bike or paddleboard somewhere high and beautiful.  I am loving the outdoors, sun and warm weather this fall and dreading the coming cold days ahead. I’ve been waiting months for more thoughtful discussion on creating safer indoor environments with SARS-CoV2 floating around.  I read University of Colorado, Boulder worked through the summer to adjust air intake dampers for their campus buildings’ HVAC systems to incorporate 80% outdoor air which increases heating and cooling costs. Hard to tell if it is helping because the kids continued to party and forced a shutdown by the university for 2 weeks for all virtual instruction with the rapid increase in cases.

But I really enjoyed your episode 666 discussing Far-UVC light!  I’ve looked for literature on inserting UV lights in HVAC systems but didn’t find much. I’d love to see someone study these lights in return air ducts to HVAC systems.  I wondered if the spike in cases in the southern states was due to hot and humid conditions letting the virus spread with air conditioning or if it truly is close immediate respiratory droplet contact.  I’d also like to see if anyone is studying elderly care center outbreaks and what kind of HVAC systems they had.  I would imagine forced air systems could be worse than radiant floor or boiler radiator systems.

Inserting the UVC lights in elevators should be a great first step.  I think I saw an airborne study of another virus in Korea or China and it stayed largely on one floor but did show some leak through the elevator shaft. I prefer the free workout equipment in the stairwell at the hospital where I work, but climbing 6 flights in a mask tends to create more moisture and still allowed just one mask per shift.

I know your shows have said fomite transmission is quite minimal in contact tracing.  I wonder if that is because the amount of virus picked up and inhaled is well below the threshold infectious dose, or if the virus just doesn’t survive long on surfaces contrary to earlier surface testing studies.  I am wondering if you think that might shift a bit during winter months.  There were quite a few studies on how long the virus was active in different temperatures and humidity.  You freeze the virus for research storage so isn’t it possible fomite transmission might be more problematic during freezing temperatures and shorter daylight days?  I won’t sanitize my groceries but will probably be more cautious touching public items. In fact, I’m not buying a ski pass this season, I bought a split board and will get a free workout skinning up the mountain and snowboard down away from others. I skied on February 29th, the day Colorado’s first diagnosed case flew into Denver and became positive in Summit county a few days later.  I remembered not wanting to touch the bar on the lift while I avoided the lodge and the crowded shuttle bus.

Thanks again for the deep dives into science and current events!

Kim, RPH
Hospital Pharmacist
Pueblo, Colorado

Katie writes:

Thanks for your podcast! I have been enjoying your interviews and discussions immensely. I enjoyed episode 666 today and thought “we should put these everywhere” this is until I thought of the microbiome. What would happen to the microbiome on our skin. Based on the article below, it might cause some issues but it seems that it might be the lesser of two evils. Though maybe when/if the virus is more under control we might use them more sparingly. This would be especially important for employees in businesses/areas that would utilize the lights. Thanks again for your thoughtful, scientific discussions! Off to buy some goggles to wear for when our campus moves to f2f next week. Fingers crossed that our students will behave since there is no testing plan…