Paul writes:

Our COO of our hospital system contracted covid 19. He had cytokine storm. multi-organ failure respiratory failure and ventilatory support. Although I’m not aware of all his treatment permutations, he did receive convalescent serum. This was in early March. He fortunately recovered and was discharged from the hospital. Now he has lymphoma. You have spoken how there’s some thought that the virus might continue to exist or hibernate in lymphocytes. Epstein-Barr virus is known to cause burkitts lymphoma. Many other viruses also can lead to malignancies, so the question is: Are you seeing an increase in lymphomas in Covid 19 patients who recover.

Thank you

Paul Detrisac MD

Critical Care

Bob writes:

I have seen some comments about covid patients from doctors I follow on Twitter. In particular, some of their patients have POTS (Postural orthostatic tachycardia syndrome).  Is Dr. Griffin familiar with this, and if so, what can be done? What is the prognosis?

Thank you,


Liz writes:

Dear TWiVers,

I am a new listener with very little background in science.  Finding your podcast has been a silver lining to this pandemic, and I really enjoy listening and learning from your discussions during my daily walks.  

I had two questions for Dr Griffin after listening to TWIV episode 645 and hearing the stories of his “long hauler” patients that sounded very familiar.

My first question… is this cytokine storm and “tail” he is seeing from SARS-CoV-2 unusual for a viral illness?

The reason I ask is my college freshmen was recently diagnosed with a form of dysautonomia (called POTS) that her doctor says can happen after a viral illness.  She was diagnosed in the ER with a respiratory virus in the Fall of 2018 (no COVID around then).  She returned to the ER 10 days later with shortness of breath, racing heart rate, and exhaustion after climbing a single flight of stairs in her dorm.  (She had an elevated D Dimer and high neutrophils but nothing serious was found.) The fatigue and shortness of breath continued.   A few months after the return ER visit, she developed rheumatory/ inflammatory symptoms (high +ANA), and then the dysautonomia started.  

Secondly, does Dr Griffin believe that the centers studying the COVID “long haulers” will be able to help those suffering the post viral effects of other viruses?

Many thanks,


Amal writes:

Dear TWIV hosts,

I have a question for Dr. Griffin. I was prescribed anti-inflammatory drugs by my doctor, for the discomfort caused by my shoulder tendinopathy. I live in Paris, France where the COVID19 pandemic is still ongoing. I work, so I take public transportation, and I also go to the gym every day. I am aware of the risks so I am very careful when it comes to wearing my mask properly, not touching my face prior to disinfecting my hands, keeping physical distance whenever possible, etc. But I am worried that if I take the drugs for 30 days as prescribed by my doctor: i) if I get infected I will not be aware of it because I will not have the usual symptoms caused by my immune response (fever, fatigue, etc)? and ii) that I will develop a severe form of the disease because my immune system will be kind of shutdown by these drugs?

Will I still get symptoms even if I am taking anti-inflammatory medication? Should I be worried?

Thank you,



Brian writes:


Dear TWIV team,

As a school board president of a small California district, I contacted Quidel to learn about their Sofia antigen test. It requires nasal swabs. They’re not  available to schools until 2021, but I doubt a school can run nasal swab tests.

Quidel’s representative wrote me that “current FDA language says that a negative test should be reflexed to PCR for confirmation. There is no language in our Package Insert that refers to transmission.”

This is the problem. FDA says they have to be referenced to PCR, and transmission is not considered relevant.

Doctors tell me the cheap, fast tests are inaccurate. When I explain they’re insensitive, not inaccurate, they say “but what about false negatives?” 

Accuracy means a result represents an ontological value . A cheap test can report “you have no more than 50,000 virus particles”. PCR accuracy states “you have no more than 999 virus particles.”  But even academics fall into the trap of pretending precision is accuracy. How many papers report statistical results to the third or fourth decimal point, when the next experiment may have results that differ by a whole number?

The FDA is unwilling to make the effort to explain testing for transmission, even if they make noise about inexpensive tests. They’re afraid of the Atlantic, the NY Times, the Post, CNN, CBS, etc., all of whom will run headlines about inaccurate tests. They’re afraid of grandstanding politicians. They’re afraid of an unpredictable, ignorant President. They’re NOT afraid of scientists or educated citizens.

Game theory says the best option is rarely chosen. If people are clever, they settle for second best. So I’ll accept pooled testing. How frustrating.


Anne writes:

Dear TWIV,

I was turned on to your podcast by TWIV 640 featuring Michael Mina and has since been an avid listener (and learning a lot).  I’ve even written my first ever letters to public officials as a result of that podcast and now I”m writing my first ever letter to a podcast.  As a pathologist who has dealt with bringing up the SARS-Cov2 PCR assay at local hospitals, I would like to point out something I haven’t heard you mention, specifically that there is a difference between analytical and clinical sensitivity. Analytical sensitivity can be described as the technical ability of a test to detect a small amount of analyte but clinical sensitivity has to account for how the test can actually identify disease with real patient samples.  Unfortunately, there really isn’t a lot of data (at least that I can find) about the clinical sensitivity of the PCR test but depending on the source of specimen and when in course of infection it is collected, unpublished data suggests a clinical sensitivity range of of >90% to less than 70% (1).   I think this distinction is important because patients that have tested negative by PCR but have a clinical presentation consistent with COVID19 should probably be tested again (or get the serology test), despite the high analytical sensitivity of the test. 

In regards to how we bring up clinical tests, in TWIV 651 Dickson mentioned that samples are sent by the College of American Pathologists (CAP) to local clinical laboratories but I think he was actually referring to proficiency testing.   The CAP does send out test samples to subscribing clinical labs but this is for tests that are already validated (as a regularly occurring quality check).  Getting samples to validate our SARS-CoV2 PCR tests was not easy especially when infection prevalence was low in our area.  This was quite a contradiction as we needed to test to keep viral spread low but because it was low we didn’t have samples for test validation.  The local health department had to send us patient samples and we use contrived samples as well with material obtained through the CDC.  Getting samples for test validation has continued to be a challenge with testing asymptomatic people, as the FDA says we cannot use a test to screen asymptomatic individuals unless it was specifically validated with samples from such people (1).  As you may imagine, such people are hard to find when the prevalence is low (although we recently have found a few such individuals, perhaps reflecting increased local spread?).  The reality is that many (most?) labs use the test for screening asymptomatic individuals as such testing is required by local and federal (CDC) public health mandates to screen people before medical procedures or for travel.  For now, if you look at the FDA EUA’s for PCR tests only one lab has approval to use their test for asymptomatic screening (3) but I hope the move by the FDA to distinguish between diagnostic and screening tests will help those of us in the clinical laboratories caught between contradictory regulations and requirements.

Thanks for allowing me to share my frustrations and for your ever enlightening discussions.





2.  From, updated 7/24/2020:  “Diagnostic tests authorized for use on individuals suspected of COVID-19 by their healthcare provider may be performed on specimens from certain asymptomatic individuals (e.g., those who are suspected of having COVID-19 because they have been exposed to an infected individual). Diagnostic tests offered for the screening of any asymptomatic individual, however, are to be validated by their developers and authorized by the FDA specifically for screening purposes.”


Lizzy writes:

Dear TWIV team, it is 24° Celsius 76° Fahrenheit in Draper Utah and I can see an occasional “falling star” in the Perseids meteor shower from my roof even in the city. On every one of them I wish that phase 3 trials of this new Russian vaccine weren’t going to be tested population wide starting with the health care workers who probably know it’s a question in a bottle instead of actual protection. 

Another concern I have is how do I explain to friends and relatives that we are expediting because we have to with this vaccine, and ours will be good and you should get the one that’s approved by the FDA, but Russia’s is bad and you should not call your Congress Critter and tell them to buy Russian vaccine, because they went too fast and didn’t show their work. 

How do I explain this to people I am still trying to convince not to eat out at restaurants and go to movies at the megaplex?

Brita writes:

Dear Team TWiV,

Thank you for your excellent podcast.  I am grateful for the time you dedicate to educating your audience.  I have been a loyal listener since March, and I have a TWiV notebook full of information I learned from you.  My family knows not to disturb me when I’m busy TWiVing.  As an amateur scientist, learning from TWiV has been a joy. 

Last week, 8/6, on the Political Gabfest podcast, the host David Plotz mentioned TWiV 640 during their “Cocktail Chatter” segment.  He talked about Michael Mina’s idea for cheap, at-home testing.  This week, 8/14, Michael Mina was a guest on Political Gabfest.  Michael spoke on a “general public” level about how cheap, frequent testing might work.  It was a nice segment, and they provided a link to TWiV 640 in their show notes.

Thank you again for you amazing and important work,

Brita in PA where it is currently 78 F and rather humid

Gregory writes:

Dear TWIV,

In TWIV 648 you discussed a box-and-whisker plot showing CT values in three age groups. In a minor slip-up, the “whiskers” of the plot were described as being “error bars”.

In fact, things are more complicated than that. The box itself is not too bad to explain: put simply, half of the data lie in the box. The whiskers are more complicated – to be honest I don’t think it’s worth going into*. Let’s just say the whiskers are decorative.

The important point is this: “error bars” reflect our uncertain knowledge of some quantity (for example, the standard error of the mean). In contrast, box-and-whisker plots show the variation that exists in the population.

Imagine that you tested huge numbers of people. Error bars would shrink to zero as your uncertainty decreased. In contrast, the spread between 25th and 75th percentile will be whatever it is out there in the world, so the box plot would not shrink.

Nothing like catching up on TWIV after a long day of making plots!

Keep up the good work!



*From the documentation of the ggplot2 software:

The upper whisker extends from the hinge [top of box] to the largest value no further than 1.5 * IQR from the hinge (where IQR is the inter-quartile range, or distance between the first and third quartiles [size of box]). 

Too complicated. In my opinion, people should just plot all of their data points and then report summaries, p values, etc.

Gregory G. Putzel, PhD

Staff Bioinformatician

Jill Roberts Institute for Research in Inflammatory Bowel Disease

Microbiome Core Lab

Weill Cornell Medicine

Tim writes:


Dear TWiVers, 

The three digits after the decimal can probably be most accurately presented as


How much precision is lost vs. the mistaken appearance of precision?


Siobhan writes:

Hi TWIV team,

I desperately want to get back to in-person rehearsals for my choir. I live in a relatively low prevalence area (cumulative incidence less than 100/100,000 of the population), and we are currently in the second wave of the pandemic. With a 2% positive testing rate (standard qPCR) and a seroprevalence of <0.5% (for anti-S1 and anti N Abs), I’m reluctant to believe there is substantial pre- or asymptomatic spread in the population. 

All things considered, my choir of 24 young adults, is considering having in-person rehearsals in September. We would be taking precautions such as rehearsing outdoors (weather permitting), physical distancing when indoors, self-screening for symptoms, improving the ventilation and sanitation, etc. After listening to recent TWiVs regarding sub-“golden standard” testing and the firefighter labrats, I was inspired. I am only a virology master’s student, but I’m well-equipped to run an assay or two each week. I certainly don’t meet the clinical diagnostic lab requirements (you need a bunch of certificates and Quality Control measures), but I have access to pipettes and a qPCR machine. It might not be optimized for clinical diagnosis, but I can ask my fellow choristers to spit into a tube 3 days before rehearsal, screen them to the best of my ability, and use the results to decide whether or not to hold rehearsal. In fact, my lab is collaborating with a group that is developing an isothermal testing kit, similar to the LAMP kit used by those firefighters. 

What do you think. Assuming everything is done above-board (i.e. I can get my PI to agree to let me use the lab, and get the choir to pay for reagents etc), would this vigilante testing method be useful to justify resuming in-person choir rehearsals? If the $1/strip tests were manufactured but not FDA-approved, should/could smaller organizations use them for private screening purposes?

Also, I’ve seen evidence for a chlorhexidine mouthwash reducing viral load in saliva, which presumably constitutes most of the respiratory droplets shed while singing. In Japanese dental practices, povidone-iodine is similarly used to reduce viral load. Obviously this would do nothing to reduce viral load deeper in the respiratory tract that is aspirated, but it does something. And isn’t something better than nothing?

Thanks for reading!

Ronald writes:

Thought you might like to see how our wonderful state is handling the pandemic.  Also thought your face needed a palm today.

Florida sheriff bans masks:

Anthony writes:

Like language, music and math, (Or should that be Language in all its forms?) from a small set of rules and a limited set of building blocks, viruses construct an unlimited number of unique statements.  With virology and infinity, I think that there’s more to it than that.

In the mid’-’70s, a Jesuit instructor in a high school Theology class explained that this was the greatest subject.  With Science at some point in the distant future everything will be known, but since God is infinite, something always can be learned.   Focusing just on his comment about Science, 45 years ago, that seemed reasonable — that it was humanly possible to unravel the thread even though that would take a long time..  Now, my impression is that every answer uncovered about the nature of reality brings with it more questions.  So, like the priest’s approaching half a century old reflection on Theology, Virology is infinite.


Jennie writes:

Hi TWiV crew,

I would just like to draw your attention to a past TWiV episode from 18th March with epidemiologist Stephen Morse, who (@ 44.25) discussed rapid, at home tests for SARS-CoV-2, even if not completely reliable. He lamented the fact that there didn’t seem to be the motivation for them and indicated how and why they would be of help. I can’t believe that was almost 5 months ago now!

I was super impressed with the Michael Minas episode but can’t help wondering how things would be if this was a thing back in March.

I have been listening for the last 100 or so episodes (many multiple times) and currently burning through the back catalogue. I have always loved science and am glad I discovered you. Thanks for all you guys do.


A Registered Nurse from about two hours north of Sydney, Australia

Michelle writes:

Hi Twivvers, 

I’ve been following since around February, and this is one of my thanks to you. 


ignorance spreads through the ‘web. 

Twiv inoculates. 

Stay safe, stay grumpy,


(A breezy 79F in San Jose)

Maxim writes:

Hi TWIVers!

Thanks a lot for your podcast. You’re really informative and accessible. I would even wager to say that you’ve made me think about biology in a way more positive fashion, since High School made me deeply dislike the field because it just didn’t stick in my head. I guess viruses also have positive side-effects!

My question is: can rain kill viruses? 

Right now my town is disinfecting the streets every day twice against Covid-19. However the weather over here in Eastern Spain has been quite rainy for the last couple of days, and I wonder if rain can also be an effective “natural” disinfectant.

Also, a report on the situation here in Spain on Covid-19:

Two weeks ago, the country entered a “State of Alarm”. You cannot go out except for work, medicine or groceries. Police and Military are patrolling the streets and roads all across the country, and if they find you in violation of the curfew, you will be fined between $700 – $25,000. If you happen to be a government worker, which also includes teachers in public universities, you can even go to jail. So far, only in my region, more than 5,000 people have been fined.

Cases have increased exponentially, however, authorities claim we are close to the inflexion point in the curve. How accurate is that I do not know, but regardless, you could think of our situation in regard to the coronavirus like a “lighter Italy”. 

Things are better or worse depending on your region, for example the Capital Madrid and Catalonia, a region in Spain, where more people live in the country, have been hit harder by the virus. It also doesn’t help that those two regions of the country have for years promoted private hospitals in favor of public ones, and most common than not, that meant cheaping out in regard to healthcare/lots and lots of corruption cases in the field. 

That’s because Health Care in Spain is decentralized, although we do have Public National Healthcare System, each region is free to manage it however it wants. Luckily in my region privatization of the healthcare system hasn’t been very popular, thus we are better off, however, the Ministry of Health has taken control of all the regional systems in order to ease out the healthcare systems of harder hit regions. In addition, the Ministry of Health has taken control of all private hospitals and effectively turned them into public ones during this Crisis. 

Also, all private companies, entities that have Masks are obliged to turn over all masks Surgical or PFF2 and higher (EU standard equivalent to N95) to the government, and those who refuse to are exposed to thousands of dollars in fines and expropriation of those same masks by the government. Believe it or not, so far 250,000 masks have been expropriated by the Police.

All in all, things are bad. However, my country was relatively quick to take action against Covid-19, and although there have been many, many more incidents I could share with all of you guys, I think that’s a good enough summary. I am more afraid for you Americans, since your National and Regional Governments have been rather passive to this threat and I am afraid many people are going to die over there because of your privatized health system and a more “individualistic” society.

Love your podcast.


Edward writes:

Hi Team TWIV,

In episode 594, Alan said to avoid sprouts. With brassicas being among the most beneficially healthy of vegetables, can I ask Alan to qualify his reasons please?

With best regards,


Tatworth, Somerset, UK

David writes:

I’m a junior doctor in the UK. I’ve really appreciated the information I’ve learnt from your podcast, especially recently regarding the coronavirus pandemic.

I wondered if you think it’s possible that the mode of transmission could influence the clinical manifestation of the disease. For example, if a person is inoculated via an aerosol, would they be more likely to develop a lower respiratory tract infection, due to the deeper penetration of the smaller particle size into the lungs?

This would have important implications for healthcare workers, since the work we do often generates aerosols.

Many thanks,


Maurice writes:

Hi to my favorite twivvers & thanks for the mug.

My doctor son is a radiologist working in France (Maubeuge).

He recently forwarded me his catscan of a confirmed cov19 patient showing a faint “ground glass” shadow in the lung. He assures me this would not show up in a standard X-ray.

I say this because Alan Dove in twiv 594 mentioned that his wife with signs of pneumonia was sent home from hospital for self isolation because of a negative X-ray.


Shows the need for availability of quick covid19 tests as a better system of triage at Hospitals.

Hope my suspicions are unfounded and apologise if they are.


Cornelis writes:

Hi TWIV Team! 

Just a little Update from Germany: 

Our CDC-Like Robert-Koch-Intitut (RKI) does provide detailed statistics about cases in Germany. The numbers differ from CSSE because of different algorithms and also how cases are submitted to the RKI.

You can either look at German states (Bundesländer) or focus on regions/cities (Landkreise).

Also there is an overview on different maps at (but as far as I can see only in German). 

Thank you for your great work, I enjoy listening to your podcast. 

Stay safe and healthy


Visto writes:

I have seen reports that there are two strains of the SARS-CoV-2 virus, the first of which is 98% similar to a Bat Corona virus, so that seems like the inspirational source.

The second strain has had a 29 nucleotide region deleted from an important Open Reading Frame (ORF8) that spits ORF8 into two and so reduces the replication ability of the virus.

It has been reported that the strain with the ORF8 segmented into ORF8a and ORF8b shows a much reduced severity of disease in humans.

The original intact strain caused much greater death and developed disease faster than the attenuated version,  in china, where later the spread of the attenuated strain subsequently reduced mortality.

Could not the attenuated virus be the proverbial cow-pox to the small-pox that is the intact SARS2 virus?

I would like your expertise on this, I am struggling to understand fully all the pieces to this puzzle.


Emily writes:

Hello TWiV,

I am a structural biologist who studies various soluble and membrane proteins using X-ray crystallography and cryoEM. So I understand only the very basics of serology, that an ELISA can be used to detect the presence of antibodies by detecting the presence of binding of antibody to a particular antigen that’s secured onto the ELISA plate; in the case of SARS-CoV-2, that would be the glycosylated spike protein.

I understand, too, that the glycosylated spike protein on the surface of some viruses, like SARS-CoV-2, must necessarily, and so do undergo many structural changes dependent upon binding to their receptor and probably to antibodies and dependent on the stage of viral infection after the infected cell engulfs it. 

I know too that it’s difficult to produce the viral spike protein for use in ELISAs (and other experiments) in the lab without cutting off the part of the spike protein that would be embedded in the viral membrane. So making a soluble version of the spike protein is one approximation to the real thing, and another is the level of glycosylation on the spike protein. SARS-CoV-2 has something like 22 predicted glycosylation sites, which is difficult to get ‘right’, I assume, depending on which expression system one uses in the lab to make enough of the protein to put into ELISA-based serology tests.

So my question is this: how do we know which protein to make for serology tests to best approximate what’s on the surface of the virus, and so what the immune system has seen or would see (for vaccinations)? Making the wrong approximation may cause serology tests to miss antibodies or to misrepresent which antibodies bind the actual spike protein.

Michael writes:

Thank You So Much – I await every new episode!

We use several food safe sanitizers for fresh produce and surfaces – much better than bleach soap and rinse that disgusted Vincent so much he gave up on lettuce!

A little help from your friends- we make chlorine dioxide solution on farm for fresh produce wash. Here is how we do it, but first a few warnings and details:

Chlorine dioxide is unstable it will spontaneously combust ( So we make it in aqueous solution attempting to dissolve most of the liberated gases in water before they escape and then we refrigerate it (inverse solubility with temperature) and then dilute it for final use. You could carefully allow it to effervesce and produce gasses to fumigate unoccupied enclosed areas (with full respirator or air supply PPE) – I believe this was used for anthrax cleanup after the postal bio terrorism a few years back.

The short and the please don’t try this at home answer is : A solution of sodium chlorite (not salt sodium chloride) and sodium hypochlorite (bleach) is acidified with hydrochloric acid thus creating hypochlorous acid chlorine gas and chlorine dioxide gas in some sort of equilibrium with it going into solution in the water – get it wrong and you produce too much gas and you might have fatal chlorine gas exposure or it explodes and you could suffer chemical burns or your mixture effervesces all over the lab bench with all of the above mentioned hazards. Interesting even with all those dangers if used in dilution chlorine dioxide is highly effective in surface sanitization of fresh produce without bad taste or destruction of the tender things like lettuce and makes a wonderfully effective produce wash with no rinsing required. (The peracetic acid peroxide washes are probably easier and safer.)

There are automatic mixing chambers industrially available for water treatment plants and such automatically and hopefully safely making chlorine dioxide solutions.

The Corona Discharge Ozone is my current go-to for room and cloth item sanitization after laundering . A simple electronic device about $200 can produce 10 g per hour of ozone from room air. It seems to work great on CPAP respiration masks and head gear as well as surfaces and all the nooks and crannies in the lab or produce handling area or even in coolers. It is often used to enhance shelf life due to its destruction of ethylene gas as well as sanitization. We apply it nightly in unoccupied areas for about 2 hours on a timer or in a chamber or cabinet for masks and small items. It can be injected into water usually under slight vacuum with a venturi mixer (devices are commercially available for spas and pools). I am currently using “Ozone fumigation” for sanitization of our delivery vehicles both in driver’s cab and cargo areas for all of our “no touch” home delivery as well as commercial produce wholesale deliveries during this Covid-19 crisis. {There is a medical grade of ozone made using pure oxygen in an enclosed corona discharge tube.}

I would think this ozone would be good for N95 masks – wonder if NIH is trying it? It might even be more effective on masks with moisture as the ozone reacts with water to create H202 – meaning a personal cabinet could be constructed where an individual stored his/her supply of masks lab coats and other PPE under ozone and reused them in rotation with perhaps only an hour or so of regeneration time. (Some parts like rubber and plastic will degrade or brittle under constant ozone so this might limit useful life cycles.)

PS – careful with microwaving n95 masks containing metal bits – like strap attachment and bendable nose clips – those metal bits become RF antennae and will create some exciting fireworks and possibly fire in your home microwave

(In case you’re catching the drift here some of my warnings above come with the validation of intimate personal experience)

Can’t wait for the next episode!


Planet Earth Diversified

Lisa writes:


I was wondering how long it takes before an infection of COVID-19 is detectable in humans. For instance if you have been exposed and the virus is in your body and happily reproducing away, how long before there is enough to be detected in the current test? How long  before it is transmittable? Is it transmittable before it is detectable in the current tests?

Thanks for all your efforts to inform the public of the actual situation!


Marietta, Ga

T writes:

Dear TWiVers,

Re: TWiV 592 “Coronavirus update – dangerous curve ahead: The mask series” (58:16)

Ori’s recommendation for the general public to not wear a mask as PPE unless they are symptomatic (therefore technically not using it as a PPE) seems to hinge on (a) there is a current shortage of masks, and (b) healthcare professionals should be given priority because they have a much higher risk of exposure.

I would like to suggest homemade masks as a “guilt-free” alternative PPE to be used at times when strict physical social distancing cannot be adhered to (e.g. grocery shopping). Here are 3 peer-reviewed articles on the efficacies of homemade masks:

  1. Tea cloth VS surgical mask VS FFP2 (european N95), 3-hour test: van der Sande, M., Teunis, P., & Sabel, R. (2008). Professional and home-made face masks reduce exposure to respiratory infections among the general population. PLoS One, 3(7).
  2. Various household fabrics VS N95, breakdown by particle size: Rengasamy, S., Eimer, B., & Shaffer, R. E. (2010). Simple respiratory protection—evaluation of the filtration performance of cloth masks and common fabric materials against 20–1000 nm size particles. Annals of occupational hygiene, 54(7), 789-798.
  3. Various household fabrics VS surgical mask, actual bacteria and bacteriophage (plaque assays!!), fit test: Davies, A., Thompson, K. A., Giri, K., Kafatos, G., Walker, J., & Bennett, A. (2013). Testing the efficacy of homemade masks: would they protect in an influenza pandemic?. Disaster medicine and public health preparedness, 7(4), 413-418.

However, it should be noted that the studies cited above were done with previously-unworn masks, while washing and drying has been shown to lower the filtering efficiency of cloth masks. (Neupane et al., PeerJ, 2009)

In view of this, people have been looking into disposable yet accessible alternatives, such as kitchen paper (paper towel) and facial tissue paper. Below is the test data published by the Consumer Council in Hong Kong from the article “Reuse Mask? DIY Mask?

(Similar results were obtained by a different group:

In the same article is a step-by-step tutorial on how to make a “makeshift mask” out of tissue and kitchen papers. But considering that the masks have to be replaced regularly, that is still quite a lot of crafting involved as a long-term solution.

Therefore, many people have designed cloth masks with a built-in slot for disposable filters (e.g. this one). The idea there is that the cloth which could be washed and sterilised (just like all of your clothes, c.f. TWiV 593 01:53:55), acts merely as a holder for the tissue/kitchen paper that is going to do all the heavy lifting as a filter. This way, the filter could be readily replaced every few hours with minimal effort.

The design I find most thoughtful though is the HK Mask (open source pattern printouts:, instructions in different languages: Google Drive). In my opinion, the distinctive features of this design are:

  1. The holes in the bottom corners and at the top, allowing a rectangular piece of filter to span the whole cloth mask without leaving gaps at the edges (step #2 below), and
  2. The drawstrings tied at the back of the head, providing a better fit than a regular surgical mask (step #4 below). 

I hope this is helpful information. Many thanks for putting out so many episodes lately. By the way, it’s sunny today in Hesse, Germany, 8°C with 24% humidity.



Jessica writes:

Hello Twiv-ers, 

Thank you so much for all you do!  Even as a non-scientifically minded person, I have found your discussions and guests to be very interesting and illuminating. There has been a lot of discussion of SARS-Cov 2 surviving on different surfaces, but I have yet to find a straight answer about about whether the virus could survive and infect someone through a dog’s fur.  

So, here is my question – if someone who is positive and has, let’s say, wiped their nose on their hand and pets a dog, and later a non-infected person pets that dog, could they become ill?  Or if your dog goes to a doggy day care and is pet by an asymptomatic but positive person, and then they come home and roll around on the couch, could the virus be transmitted from person to dog to couch to person?  My interest in this general, but also selfish since our two year old rescue pup is going stir crazy inside (I have had a head cold and my husband is working from home very intensely so no long walks at the moment) and currently there is still the option of sending him to daycare, but we don’t understand the potential risks!

Thanks for your input!



P.S. Currently in West Michigan it is cloudy and 32 degrees with an inch of snow on the ground. Not great.

Joan writes:

A questioned for the esteemed TWiV panel, 

I have been wondering if beards, and long hair could be a mode of transmission for viral particles. I heard it mentioned that extra hair can be a problem for the proper seating of PPE, however I am thinking of hair itself as a surface.

I know they had a campaign during the TB epidemic for men to sheath their beards.

One reason I ask is because I work in a lab, and even though I have a biosafety hood to do work in, some of the students with long hair will have it hanging down. And even when it is tied up in a pony tail, it will swing out quite far when they turn around. 

It used to be that nurses, if they had long hair had to have it tied up in a bun, I am not sure about doctors with beards, but I know they told them to get rid of ties in more recent years.

With mountain-man beards, and long hair being back in fashion I am wondering if hospitals, clinical testing labs etc., are trying to mitigate this possible risk from all employees, or am I just over thinking things as usual.

Thanks for your podcast, I enjoy listening to it when I am sitting at the hood. 


Lewis writes:

Dear TWiV team,

I’m the guy who did the big study of science podcasts which was a pick of the week back on TWiV #500 (July 2018) and subsequently published in Royal Society Open Science in 2019. One of my long-term research goals is to conduct further meaningful research into science communication. Currently I can think of no more important topic in science communication than public trust of science and dissemination of reliable information.

In this time of disinformation and panic around COVID19, a recurring theme in your listener emails is how much listeners trust the information from TWiV and how it has prepared them to combat disinformation about COVID19 that is prevalent in social media. This enables your listeners to become “ambassadors” for reliable information and equips them to counter disinformation. I think for TWiV this trust arises from having excellent hosts and guests, who provide information in a level-headed, conversational, and candid manner, with appropriate authority, scepticism, honesty when necessary.

I thought it might be interesting for the TWiV team and listeners to know that it has long been asserted in media studies research that radio and podcasts are perceived by the public to be particularly trustworthy. Audio is a “blind” medium, allowing listeners to engage with the content in a more active manner, e.g. by imagining the hosts, projecting assumptions onto them, and thereby relating to them more. In comparison, TV is passively consumed, is very stage-managed (and is obviously hyper-partisan in the USA), and therefore may be perceived as inherently less trustworthy to certain viewers. Additionally, people often listen to podcasts in very personal settings (e.g. in the car or shower) and podcasts have a conversational tone. This might help listeners feel like they are opening themselves up to “be part of the conversation”, even if they aren’t doing the talking per say. Further, they can of course reach out via email, which you engage with frequently. Overall, the podcast medium and the format of TWiV seems to be quite the recipe for instilling trust in science.

It has crossed my mind that COVID19 could perhaps be an interesting crucible to test public perception of science communication mediums. However, as a postdoctoral researcher, about to embark on a short and intense (3 year) research fellowship, I can’t really dedicate the time or resources to conduct such a study, which would surely require in-depth collaboration with social scientists.  In the meantime, I will keep sharing each new episode of TWiV and keep telling everyone to wash their damn hands.

Socially distant regards,

 Dr Lewis MacKenzie

Postdoctoral Research Associate and BBSRC Discovery Fellow

Durham University Chemistry Department, UK.

P.S. Now may be a good time for someone to write a mini review or case study on virology podcasts. For example, just this month Clarke et al. published a mini review focusing exclusively on radiology podcasts.

Paul writes:

Hi TWiV gang

This is Paul from Buffalo.  Hi Rich!

A prior PhD student of mine, who happens to be from China, and now lives  in Boston MA, told me that friends of his from China are mailing him  anti-SARS-CoV-2 IgG/IgM test strips.  Have any of you heard or even seen  these?  If they work, even moderately well wouldn’t this be a  game-changer? I guess a key issue would be how specific they are for this virus vs other coronaviruses? Is there any effort to get these tests from China and test them out?


BTW I’ve become a super-spreader of TWiV




Department of Biological Sciences

University at Buffalo

Anne writes:

I love TWIV!  I’m a new listener, 65 years old, retired public health policy professional.  My son (a journalist) turned me on to TWIV!

Question:  Is there any benefit against the coronavirus (or any other infections) from getting the annual flu vaccine?  Does the flu vaccine ramp up the immune system in any way helpful against other viruses?

Thank you.


Bethlehem, PA

Paul writes:

Hi Twiv team,

These podcasts are among the world’s greatest treasures. Thank You All!

Are there any reported cases of coronavirus co-infection with flu?

33F and rainy in Indianapolis, but the forecasts are looking good. 

Craig writes:

Dear TWIV,

Big fan and will likely continue to listen long after COVID19 is gone.

I’m a meteorologist in Florida where we frequently deal with hurricane threats.  To help understand how to prepare, we often use analogs of previous storms and their impacts.  My question, are there analogs for the present coronavirus, say original SARS, and can we apply that in a predictive fashion to help prepare and respond effectively to this virus?

Thanks in advance,

Craig Setzer


Evan writes:


I have found my way to your podcast very recently. I was hoping you could explain a question about how this virus is possibly working. Why are the elderly more vastly impacted and children under 10 barely impacted at all? Why would this disparity exist? Do other viruses like this exist?



Greg writes:

Thank you for the wonderful service you give to the world, my vote is NIH should fund the entire TWIx for all the free public work and benefit you provide to the citizens and research community as a whole,  am certain your shows have motivated a large number of desperately needed students to follow a path in microbiology. 

You had looked at  zinc lozenges in a 2009 blog post,  and were skeptical so decided to pass based on a inconvenience/slight reward analysis, but as it might offer benefit to coronavirus where the inconvenience/reward ratio is different, your thoughts on James Robb’s suggestion? There are FDA warnings for those trying intranasal zinc products.  Zinc is known to inhibit bacterial growth, also can act as a signalling molecule for the immune system, activate T-cells (which may be a negative in the case of severe respiratory disease that is largely caused by an overactive immune system), but not clear on possible mechanisms that make it effective vs rhino/corona or other viruses which appears only when in lozenge form?  A lot of examples of cooperation between microbes (bacteria, archaea, yeast etc) and viruses, maybe even virus – virus tag team vs host?? 

James Robb suggestion:

Roles of Zinc as a signaling molecule for the immune system:

Slim writes:


Its 3 degrees celcius and cloudy here at 9:30 p.m. Sunday night in Montreal canada. First of all great podcast thanks for keeping everyone informed with facts especially in the age of troll social media and fake news.

There have been articles in the past few years about zombie viruses emerging from permafrost reappearing due to global warming thawing, is it possible the COVID 19 is one of these and would it be something visible from a look it’s genetic code? 

Thank you, 


Bob writes:

Thank you so much for being an intelligent source of knowledge regarding COVID-19.  I believe you have many listeners that, like myself, found your podcast in an effort to educate ourselves on the virus.   I think the most obvious question we would have is: what the hell did you guys talk about before COVID-19???

I’m guessing the pod was geared more towards academia.  Do you find the podcast more or less enjoyable now that you have to dumb it down a bit for morons like me?

Thanks again for the great information.


Ryan writes:

Dear TWiV hosts,

I am a graduate student in David Baker’s lab at the Institute for Protein Design at the University of Washington in Seattle. I have been a listener since taking Dr. Spindler’s Micro 315 class in 2017 and have enjoyed the recent discussions on SARS-CoV-2. 

In episode 590, another listener asked how members of the general public can get involved in helping researchers study and develop therapeutics for the coronavirus. I would like to point out a couple ways that people can volunteer their time and resources, regardless of skill level. 

First, the Baker Lab has developed and hosts a video game called Foldit where the objective is to predict protein structures and design proteins to have a given shape and sequence. We periodically send out puzzles with certain objectives/constraints to get players to design interesting proteins for us. We even order some of these proteins as DNA, express, and see if they fold and function correctly. Of course, we give credit to the players since protein design is hard work (see author list of attached papers)! In response to the coronavirus outbreak, we’ve posted several puzzles aimed at designing antiviral spike-binding proteins, which we will test for efficacy. Listeners can learn more at the website or read this GeekWire article. I think this is a really cool way for people to get involved, have fun, and learn something about how proteins fold at the same time. 

Second, for those people who are not in to playing video games but still want to help out, the Baker lab also runs a project called Rosetta@home. This is a program that you can install on your computer which uses the Rosetta protein modeling suite (the same software powering Foldit under the hood) to help predict the structure of a protein. One computer doesn’t have enough power to predict the true structure of protein very quickly as it requires many thousands of predictions before it can have enough confidence in a given result. However, many computers distributed throughout the world can work together, each contributing one or two predictions so we can zero in on an ensemble prediction of the true structure much more quickly. This is a great thing to have on in the background since it’s configured to only run when you’re not using the computer. Rosetta@home was used to predict the structure of the prefusion form of the spike protein, which was later solved experimentally by cryo-EM (see Wrapp et al. Science 2020). You can read more about this in this forum post, or in this news post on the Institute for Protein Design website. Unfortunately, there’s no mechanism to specify which problem your computer works so there’s no guarantee that you will be helping with SARS-CoV-2 proteins. However, any resources you can contribute are immensely appreciated and put to good use! 

Thanks again for all your level-headed coverage of SARS-CoV-2!

Ryan Kibler

PhD student, Baker Lab

Biological Physics, Structure and Design

University of Washington, Seattle

Niall writes:


To answer your caller’s question (from episode 590) about how people can help with their computers (no expertise required) rather than their wallets:

Keeping this email short and to the point because i’m currently showing some symptoms myself, but of course that could be anything.

Keep up the good work!



Amy writes:

Hi Twivsters!

I absolutely love your podcast. Thank you being an island of calm and logic in the midst of the coronavirus panic.

I’ve been looking around and have an unanswered question about how how seasonal changes could impact coronavirus infection and transmission. 

From what I understand, warmer weather brings a host of protections against pathogen spread and disease severity: less close contact in small spaces, increased vitamin D production, we exercise more, UV light can destroy pathogens, and changes in our melatonin levels may protect us. (I’m summarizing this article)

I keep seeing assumptions that COVID-19 cases will fall in the summer, but can’t we look at current data to test this hypothesis now? The virus is spreading worldwide, including in the Southern hemisphere and in equatorial regions. Do you know if anyone is testing this idea? What would we need to find in the data to know if the summer offers any protection for those of us in the Northern hemisphere?

Thank you! And keep up the amazing work,


Portland, Oregon

Eric writes:


Started listening regularly in January. I’m not fully caught up so my apologies if this was answered in the most recent episode. I’m an engineer with some limited medical background.

The general assumption has been that covid-19 can be gotten, you’ll have an immune response and assuming you survive the infection, you’ll be immune to it. (Same thing with SARs.) There was (as discussed on TWIV) news articles that were likely sensational and not true about reinfection.

Influenza is a different virus and the strain mutates and different strains travel through the human population regularly. A subset of colds are also corona virus. Are we just getting different strains of corona virii when we get colds (along with the other forms of colds?)

Why is sars and covid-19 considered one and done vs the cold? Is it just a function of the rate of virus mutation compared to influenza?

I hope my question was articulated clearly enough.


Amal writes:

Stephane writes:


I am a clinical virologist in Tahiti French Polynesia, French speaking, but I listen to you almost every week (sometimes with some difficulty with my English) and I wanted to thank you for the quality of your podcasts. Currently, taking a step back from the health situation that occupies everyone is a most welcome breath of fresh air. Your regular or guest speakers are always of rare intelligence, and it is good that the work you do is widely disseminated.

Thank you

Kind regards



Cookie writes:

Your statement in your last podcast, about trying to stop touching your face in an attempt to reduce the spread of viruses reminds me of the joke of an Australian horsemen who started rubbing horse shit on his chaffed lips,

 his mate asks “does that really work?” 

No but it stops me from licking them!

Maybe we should put our hands in horse shit both to stop touching our face and to keep on our diet’s!