Michael writes:

Toilet paper = camouflage for the mummy apocalypse obviously.

Best regards,


[ad: my sister commented that the canned beans were also sold out at the store, so “mystery solved.”]

Scott writes:

Hi Guys, there was a lot of excitement about a month ago on initial good results for Remdesivir.  There were studies I know started in mainland china and other places. Since then however all talk of results from anti-viral drugs have gone totally silent. Does this mean they aren’t working?

There was also a peer review paper published by the Guangdong health authorities on using chloroquinine to treat a very large number of covid19 infections and they showed positive results, but seemed to not have had a control group.

Here’s a more recent paper on Chloroquine, do you think this is worth looking into?


I’m an american living in Hong Kong, and we have been mostly staying at home for 2 1/2 months already, so have had plenty of time to follow the research as well as binge watching netflix.  The control and quarantine measures here have been working fantastically well btw to limit community spread.


Judy writes:


It’s 90F / 32C sunny and humid in  Singapore but since we are near the equator it is pretty much the same every day. I first wrote to you Feb 10 surmising based on what I was seeing in Singapore that I would expect to see widespread cases outside of China in 7 – 10 days. Shockingly I was correct almost to the day! This is one case I wish you guys were right and I was wrong!

To follow on to my observations in Singapore and implications to the rest of the world, I was wondering if you can comment on the use of HIV antiviral currently in trials? In this video the government produced, the patient refers to getting HIV treatment early on in her diagnosis. I also found this link: 


As Singapore has had almost 250 cases with about 15% serious and no deaths, has anyone posted any papers on their therapies and whether they can be widely applied in other contexts?

I am still an avid listener of the podcast and I love the expert scientific commentary regarding the current situation. Thank you so much! Keep up the excellent work. 



Ryan writes:

Hello all,

You may have touched on this before, but I have a question regarding SARS-CoV-2’s classification and mechanisms. I had read a Scientific American article on Remdesivir, the drug tests to use for COVID-19, and was a bit confused by the wording.

Remdesivir works by inhibiting an enzyme known as an RNA-dependent RNA polymerase, which many RNA viruses—including coronaviruses—use to replicate themselves. In contrast, retroviruses, such as HIV, are RNA viruses that use an enzyme called reverse transcriptase, which creates DNA from an RNA blueprint. But our own cells also rely on enzymes that transcribe DNA, so it is much harder to inhibit such enzymes without harming our own cells. Because coronaviruses use RNA-dependent enzymes, an antiviral such as remdesivir has a good chance of working against them, De Clercq notes.  

I was under the impression that this was a type VI, retrovirus, according to the Baltimore classification. If that is the case, would SARS-CoV-2 not use reverse transcriptase? 

Thanks for the great podcasts. I love listening!




Steven writes:

Dear TWIV team,

I’m a long time sporadic listener who would like to add to the chorus of thank yous for providing such a valuable service.  With the volume of misinformation out there I truly appreciate your “goldilocks” position of providing facts in a non-sugar coated, non-alarmist way.

I am an organic and medicinal chemist (organic in the chemistry of carbon, not whole foods sort of way) with 25 years of industry experience who is now working for a non-profit effort on a very old microbe that kills > million each year but doesn’t seem to attract much attention.  I travel quite a bit internationally so I have been following CoV since late last year.  My question is in regard to the CFR and the effect comorbidities have. Most reports I have heard mention the obvious, immunocompromise, cardiovascular, and such.  I also believe I heard, maybe from you, a reference to cigarette smoking. So, do you know if it the data is available regarding the effect on CFR due to coinfection?  I’m thinking flu, HIV, and possibly TB. If there is any indication that the CFR is significantly higher with TB, which I fear it might be, then the impact on developing countries that have serious TB problems already could be catastrophic.

To balance that disturbing possibility I would like to offer a little hope.  I took a quick look at the original remdesivir patent (aka GS-5734) and I was pleased to see plenty of enablements and at least 60 or so analogs described.  What this means to me is that Gilead probably has many more of this class of compound in their screening deck and is no doubt looking to see if any are significantly better.  In fact I’d wager that every pharma that ever dabbled in antivirals is currently screening their collections as well.  While I freely admit, even as an avowed “small molecule” scientist, that there has been no greater contribution to human health then vaccination (and this includes penicillin) I know that developing a safe, effective vaccine takes time.  And while remdesivir is not that far from approval and might have some efficacy, it suffers greatly from being parenteral.  So, with a little luck, a better agent might be rapidly identified with improved efficacy and more importantly oral bioavailability.  No guarantees of course, but the testing, approval*, and production of such a molecule could be faster.

This brings me to my final point.  You’ve mentioned before that proactive research on producing antivirals for just this type of occasion would have been a good idea-no arguments there.  You also point out that there was little incentive for pharma to invest the kind of money it would take to do this without the possibility of a return-I agree again.  The business case for non-chronically administered antibiotics is just plain awful. In my opinion we need a “fire-department” model for this class of medicines.  Most people willingly pay taxes to cover their fire-department even though they hopefully never need it- but when they do it’s there.  Antibiotic research and development should be the same because next time this could be much worse, and there will be a next time.

Best regards,


*under some kind of compassionate use

Alexandru writes:

Hello TWiV,

My name is Alex and i’m a IT-Student in Vienna and i’ve recently came across your podcast because of this recent outbreak. I hope you can answer my questions to put my mind at ease if that’s ok.


I recently been going down the rabbithole and kept reading about cytokine storm. I don’t know if there is proof for this to happen with this virus, but I could imagine this to be a cause of people fainting(someone mentioned those in the last podcast)? And if so, how can someone stop that? Immunesuppressive/modulating drugs(oseltamivir e.g.)?

I’m in my early 20s with no pre-existing conditions. I get paranoid when I keep reading about cytokine storm, because it could affect healthy people. If you could talk about this phenomenon, that would be great.


What is your opinion on this? They’ve been working on a vaccine for IBV and are trying to adjust the vaccine for SARS-CoV-2. Is the timeframe they mention realistic?


An extra link if this interests you. They’re predicting that Seattle is now what Wuhan was on the 1st December.


Cheers and a thank you for answering the questions in advance. 

If you have too many questions for the next podcast, I would be happy with an answer via email too.

Only positive side for this virus, is that I have a new podcast to listen to. Thank you for going only by facts. 

Also, I keep reading that the virus binds to furin protein instead of ACE2. What would this mean? that it would stay dormant like Hep B, HIV, Herpes or only that it’s more infectious?

All the evidence towards the furin protein argument, still needs to be “peer-reviewed”, but what could this mean if that’s the case?

Alexey writes:

Hello TWIVers,

I have just seen a question in the Subject line in a recent publication in The Lancet – what do you think about this?

Thank you very much for years of most informative podcasts that I appreciate very much. Article in question can be seen here: https://www.thelancet.com/pdfs/journals/lanres/PIIS2213-2600(20)30116-8.pdf 


Alexey M. Chumakov, PhD

AHA guidelines https://www.acc.org/latest-in-cardiology/articles/2020/03/17/08/59/hfsa-acc-aha-statement-addresses-concerns-re-using-raas-antagonists-in-covid-19

Dominic writes:

Thank You for what you do. Can you comment on the possible role data of ACE receptor blocker to treat COVID?


Dom Roca MD-PhD 

(But I am just a medical doc now)

Steve writes:

[ad: advocates bowing instead of handshakes; alcoholics on the psych unit inhale hand sanitizer; handwashing craze could reduce other contagions; why not answer blog comments on the show; ACE inhibitor question (see Alexey’s link); can SARS-CoV-2 recombine with SARS or MERS] 

Hi Vincent et al,

Just finished listening to your latest excellent and informatwiv podcast.

It strikes me that an awful lot of unnecessary Purell VOC pollution could be avoided if Americans ditched their curious obsession with shaking hands/exchanging biomes, in favour of the tried and tested Japanese custom of bowing instead. Who knows?: this custom may indeed be responsible for the general longevity of the Japanese people! 

(Incidentally: I stayed in a psychiatric unit once, and observed that the communal hand sanitiser dispensers were emptied by the patients as fast as they could be filled: they really need to find something else to use in units largely occupied by alcoholics. They inhaled the lot in no time!) 

Also interesting to speculate that the current craze for quarantining and handwashing, may actually mean that the SARS-CoV-2‎ ‎pandemic results in an overall reduction in deaths from respiratory diseases by the time it’s over! Every cloud has a silver lining.

Another point I’ve been wondering about, is how Vincent coordinates comments made to the different podcasts and blogs? Not to criticise one with such a tremendous output, but I have noticed that comments to the Virology Blog pieces do not seem to get followed up anywhere, but, apart from this, I wondered if comments related to the pandemic that are made to the less frequent podcasts might be usefully collected together by subject and answered all together?

I think it was in the TWiEvo podcast that I asked if it might be possible that those who are taking ACE inhibitors for blood pressure might be getting a degree of protection from binding of the‎ SARS-CoV-2 virus to our lung epithelium, as you seemed to be saying that it was the ACE receptors that the virus utilises for entry into cells.‎ Maybe we would have to deliver it by inhaler rather than capsules to get any benefit, perhaps?  I’m mentioning it again here in case there is some time before the next TWiEvo.

I meant to ask one more thing following your discussion of the mutation/reassortment of the virus particles in a way that might increase virulence or produce new strains of virus altogether: given that this may be a pandemic, what might be produced if someone with MERS also got infected  with the new SARS?

Probably an academic question in view of the likely speedy demise of the former, but it might be worth discussing.

Many thanks for all your brilliant work.


in Luton, England, where all is grey but at least the first blossom is out on the early plum trees.

Jeff writes:

[ad: clarification on the Goldberg drum and aerosol vs. airborne transmission]

Hi TWIV – in your recent episode on coronavirus (excellent, btw) you mention the MedRxiv paper showing that the virus stays alive in a Goldberg drum for 3 hours.  I think its *really* important to tell people more of the details about that study.. I am not an expert by any means but the Goldberg drum looks to be a way of keeping aloft particles that ordinarily would succumb to gravity. Below is a link to the 1958 paper that I think introduces the drum and the very first sentence is very revealing.  I am a little concerned that the average person might see this study and conclude that coronavirus stays aloft for 3 hours, which does not appear to be true – or at least does not appear to be true in the vast majority of cases (?). I almost did a short episode about this very MedRxiv paper on a podcast that I contribute virus-specific episodes to, but decided that its just far enough out of my wheelhouse that I don’t want to for fear of  saying something not true about whether this virus can or can not be transmitted via true airborne transmission. I have already seen news articles that literally are saying “coronavirus is spread through airborne” and reference this MedRxiv paper.

Keep up the great work, thanks – Jeff in Atlanta

Goldberg drum: Goldberg et al. 1958 American Journal of Epidemiology (link

tracksidescience.libsyn.com – A podcast that a friend and I put out, mostly as a way to carve out time for two Dads with young children drink alcohol and talk science… I am occasionally able to get virus-specific episodes out (would love some criticisms btw).

Chuck writes:

I am a pilot with a major U.S. airline, regularly flying Boeing 787s to South Korea and China (until this month). On all Boeing and Airbus aircraft operated by major airlines, cockpit air is supplied directly from either engine bleed air or (787) an electric compressor. The air is fresh, never recirculated, and supplied at a pressure slightly higher than that supplied to the passenger cabin.

Just though you’d like to know.

Thanks for the great podcast! 591 is the first episode to which I’ve listened, but I’ll be a regular from now on.

Chuck Lutz

Colleyville, TX

Elaine writes:

Dear TWIV team,

Love your podcast, often learn a lot. However, taken together, what you said about mask and respirator wear in TWIV 590 was a real mess of contradictions even within this one podcast. Putting the research you described and everything else I found together, I’m afraid the dirty truth is: 

– there is pretty good evidence that both surgical masks and N95s protect the wearer, at least a bit, even when worn by laypeople, even against influenza which, since it’s spread by aerosols, is probably tougher to protect against than SARS-COV2;

– and the many pronouncements by CDC, WHO etc to the contrary are just propaganda aimed at preventing panic buying.

Since one of you also said something about clear, accurate information being important,  wouldn’t it be better if you said this clearly, and perhaps went on to discuss which of the possible mask-substitutes most people could make at home might be useful? Intuitively I think that even some quite basic home made masks might be useful against droplet spread – preventing the wearer touching their nose and mouth, and catching some proportion of droplets. Maybe even those people wearing cut-down plastic bottles over their heads are onto something, compared with not wearing anything?



Dominic writes:

Hi Twivologists,

I’m a new listener and appreciate the detailed, even-handed information. 

I have the real mask question no one is asking:

Why do you continue to ignore the efficacy of Middle Ages plague-doctor masks?  Surely the elongated beak places additional distance between us and anyone who is infected, and the flowers and herbs packed into the beak will act as an effective filter to COVID-19?  Have you seen the study that supports the efficacy of this solution? You can read it here: www.misinterpretedorbogusstudy.conspiracy

Tongue firmly in cheek,


Vanessa writes:

Hello TWiV Team, 

Love the podcast! It’s always great to learn more about other heads of the  healthcare hydra. 

I have a clarification Q: A man named Erik asked a Q about Public Heath measures in S. Korea (03/07 show). He asked if the virus on a mask would be dead after a week or so. I’m also wondering this.

This question was not answered. I actually know a few subway riders in NYC with limited masks (with underlying health issues) who are wondering if they can reuse their masks if they rotate them out (assuming they take off and store properly).

Also, Erik (Eric?) mentioned drive-thru testing viability in the US. No one on the show thought this was a good idea (or maybe not viable, wasn’t clear). 

I don’t necessarily agree. It would be great to hear your opinions on why everyone thought this was a bad idea. 

A very specialized and small version is currently implemented in Seattle (w/in a very specific population. I’m assuming based on results, this could be expanded) https://www.npr.org/2020/03/08/813486500/coronavirus-drive-through-testing-centers

Another Q: Ever consider a podcast where you have a public health guest sit in? Even other experts to come on and answer some of the more policy/strategy Qs could be fun given that the current outbreak requires this multidisciplinary  coordination from all areas of the very fragmented healthcare system (e.g. policy, epi, virologists, hospital strategists, public health communications experts). it’s a joy to listen to your podcast and learn more about viruses and all their complexity. It would be fantastic to have a special COVID19 episode with other area experts discussing COVID19 (since it will likely be discussed again on the show). 

 I must admit, I’m bias since I’ve worked in the areas of public health/behavioral economics, and hospital strategy and planning. 

Thank you!


Jackie writes:


I keep Curad brand antiviral face masks on hand just in case there is a bad seasonal flu, or some other viral epidemic. These are not standard face masks that work as a filter. They claim to inactivate 99.99% of influenza viruses after 5 minutes of contact with the mask in laboratory tests. The outer layer is designed to absorb aerosol droplets and inactivate viruses by lowering the pH with citric acid. The inner layers are coated with copper and zinc ions, designed to bind to negatively-charged side groups of the influenza virus.

Do coronaviruses have negatively-charged groups, and would you expect this mask to be effective against coronaviruses?


Randy writes:

Hi Twivonauts,  

      I love the podcast, thanks for what you are doing!  

I want to ask you about using elastomeric respirators for coronavirus.  CDC has suggested these could be a backup option for health care providers in a crisis when N95 disposable masks are not available.  Trying to actually set this up raises a lot of questions.

1) duration of filter use – there is little guidance on how long the discs or cartridges last –  some sources say it 30 days, 40 hours, or until breathing becomes difficult. How long do they* last?

2) how to clean – Daily cleaning of the masks with detergent and disinfectant submersion is recommended by the manufacturer*, but some sources just talk about daily alcohol wiping.  What is a recommended way to clean?

3) biggest question:  reattaching filter discs or cartridges –  It remains unclear whether detaching the filters before cleaning, then reattaching the cartridges to the mask after cleaning the mask is a viable option (without high risk of self inoculation), whether you can leave the filters attached and wipe around them, or whether you need to get a new disc or cartridge each day.   

Do you know anyone who has some answers?  We listeners understand the topic is not well studied yet, and we pursue any possible protocol at our own risk.  Yet some of us are hungry for expert advice, as we may have to make decisions about this under pressure in the near future.

Thanks!   – Randy

*For the sake of discussion, I’m considering a 3M model 7502 half face respirator with 2091 or 2097 pink disc filters.

P.S. A few health care facilities such as Texas Center for Infectious Disease have already used them in a clinical setting.  

Jerald writes:


In Hawaii at 82F but w. Nice but windy.

I’ve enjoyed your weekly show but I have two comments:

  1. I don’t buy the assertation that N95 masks do not protect the person wearing them from COVID19.  Simply put, if that were the case then us doctors would not be wearing the masks when seeing high-risk patients.  And I don’t think all the PPE is to protect the patients from our germs.  

Whatever study argues this needs closer examination on your show AND the routine behavior of doctors — well, everywhere – in dealing with communicable disease needs to be convincingly discounted.  To argue the masks are of no benefit to the average user is disingenuous. If the policy recommendation is to prevent hoarding and diversion of the masks, then say that. Even if the mask only reduces risk and does not eliminate it, it still is useful.

On a related note, I think it was your guest who met someone wearing a mask on a plane that offered them a mask, as well.  The doc politely refused but then privately laughed at the woman when he noticed her raising the mask to eat peanuts or something.  Frankly, so what? Using the mask as she did limits the period of vulnerability to the time she is doing her eating. Smart of her.

There is the pervasive rumor that thr virus was accidently manufactured/released in China.  Stupid that this may be, I’d like to hear a clear and descriptive analysis why this is wrong.  I believe it is wrong but the explanation why is not self-evident to non-virologists and, unless the argument is dissected and discounted, the myth will continue to gain traction.  


Jerald Block, MD

Per writes:

Why are case # dropping in China and S Korea? Is the virus beingcontained – or is population immunity on the rise?

I suspect the latter and serology could quickly provide the answer.SARS-COV-2 grows in VERO and it should be relatively simple to perform neutralization test on a few 100s of properly selected samples. This is what we did 35 yrs ago when we had emerging PRCV coronavirus in pigs.
There must be a reason that countries are reluctant to start (orreport) serosurveys, is this because it would reveal that the whole exercise on containment has failed its purpose?? I cannot think of a scientific reason for not doing serology, only political….


Per Have, DVM, PhD

Jake writes:

Hi Twiv Team,

I, like others, have recently started listening to your podcast to stay informed about the COVID19 pandemic. I’ve found it to be a nice counterweight to the anecdotal panic seen on social media.

I’ve heard you mention a few times that after the fact serological studies can be used to determine the true number of infections. However, I’ve thought of another very important use for such testing: It’s been estimated that up to 86% of cases have gone undetected. Given this high number, it’s possible that there are large numbers of people who have had COVID-19 and are now immune, but are still self quarantining because they don’t realize they had COVID-19. It seems to me that if we could perform mass testing and let these people know they already had the disease and can go back to work, that would have a large impact on keeping our economy afloat.

With that thought in mind, could you please go into more detail about serological studies? Who performs them? How can they tell if someone has been infected? Could we think about issuing “COVID-19 recovered” certificates to allow those people to break quarantine? Who would issue such a certificate?

Thanks for all you do,


Amy writes:

Hi Team,

Thanks for keeping so many people up to date during this crisis.

I’ve been curious: Is anyone exploring the power that SARS-CoV-2 antibody testing might bring?

Since US testing is a mess, there may be a point in the near future where it makes sense to start testing people who think they were already infected. From there, we could (assuming the research strongly shows when virus shedding stops) identify a work force that is safe from adding to community spread.

We need people who are safe to take on health care worker child care, food delivery, and lots more.

My understanding is that the test already exists, but mobilizing to use it in this way…I haven’t seen anything. Could something like this possibly work on the scale we would need?

Thank you so very much!


Rafael writes:

What a wonderful resource during these troubled times!

1: Is there a test that can show that you have immunity from SARS-COV-2 and if so how should this be used now and in the future. Wouldn’t this show how many people had low grade or non detectable infections.

2: Given what is going on in Seattle: should Portland OR now be starting to use the same social distancing measures and school/work/event closures that are being put in place there? We haven’t had any positive cases for a few days so maybe a lull, but Costco was bought out the day after the first case.

From rainy today in the Lake Oswego hot zone

Rafael Gray MD 


Sarah writes:

Hi TWIV Crew,

I have a question for you. Earlier this year my partner and I FINALLY decided to start trying for kids. We’ve been together for 10 years but it is only now that we are both done with our educations, post-docs, etc and at least one of us has a permanent job and the other has fairly steady teaching/research work too. So, we started trying earlier this year. I have read that there seems to be no evidence of pregnant people being affected any differently by the COVID-19, but it’s not unreasonable to think that there could be co nsequences for mom or baby that we do not know about yet. Maybe a bigger possibility is that a pregnancy outcomes could be negatively affected by the medical system being overwhelmed by COVID-19. Do you think that we are at a point where people should avoid getting pregnant? On an individual level there may be too many factors to make a recommendation, but what about across all people getting pregnant at a population level? Do any of you think that it is personally or socially irresponsible to try to get pregnant at this time? 

Thanks so much for your great discussions! My partner has been listening to your podcast for years and years and I just discovered you when putting together a lecture on virology earlier this year and I’ve listened to every new one since then.

Please stay healthy!


Glynis writes:

Dear TWIV Crew, 

I have been listening off and on to your for a couple years and love the show. I was so thankful when this started happening that I already knew where to go to get some solid scientific information, and have recommended your show to others. I started with “this podcast will kill you” which another show on infectious diseases. It’s geared a little more towards the lay person than your show, but it led me here when I wanted more of a virus fix. I’ve learned so much from listing to your show and enjoy it very much it’s scientific and I have to google some of the terms you use but that is happening less and less! 

My question is this, I’m planning my wedding for October of this year. As things get more and more serious I’m starting to worry that it may not be a good time to have a larger gathering of people. My dad is over 65 and has diabetes and COPD. My mom is over 65 and has had a heart attack. My brother’s wife has some auto immune things as well. At first I thought “surely things will have blown over by October” but now I’m hesitant to keep putting money into something that may not even be allowed or something that if it is allowed no one will want to come to or that if people do come to could lead to someone I care about getting sick! On top of that we got our tickets for our honeymoon flying into Rome later in October. I know this is a small potatoes in relation to a worldwide health crisis but I’m not sure what to do. Do I keep planning and paying for stuff? I don’t know that we can get back the down payments we have already put on things but I doubt it. What would you do if you were in the middle of planning a big event that is 7 months out? What about plane tickets into a hot zone do I book the hotel? Should I wait a month and see how things are? I told my mom we should really try to get event Insurance but I’m worried they won’t feel like selling that right now. Just curious what a virologist would do in my shoes. Thanks again for a terrific podcast. I’ve even thought about going back to school to do something in virology but as a former art student wasn’t really sure where to begin. If you have any thoughts on that I would greatly appreciate it as well. 

P.S. as a person in a younger, less at risk demographic I have offered to go out shopping for some people I know in more at risk demographics. What advice would you have if I do need to do this to risk the spread of infection on the surfaces of the things I may end up buying for other people. I want to help keep them from getting sick not be the cause of it. 

Thanks again! 


Leah writes:

Hello TWIV!

I am thrilled to have found your podcast while searching for factual information regarding COVID-19.  It’s been useful and comforting for me, and I am sure for many others, to access information presented in a rational manner. I am excited to continue to listen and learn. 

I am a school nurse practitioner at a small school in Philadelphia. This past Friday all of our schools were finally, officially closed, and will remain closed for two weeks. While this does create some obstacles when it comes to delivering services other than education (such as meals and activities which some families rely on), I strongly believe that this is necessary in order to “flatten the curve” and prevent our health system from becoming flooded with COVID-19 cases. Up until this past year I had been an Emergency Room nurse in Philadelphia. During my ten plus years working in the ER I have witnessed overcrowding and the struggles associated with providing care to sick patients in a system that isn’t equipped for the volume of patients or the severity of illnesses seen typically without a pandemic. With the recent closure of another large hospital in Philadelphia, I don’t believe we are equipped or prepared for this.  While part of me is glad to be working from home, holed up with my own children, and satisfied to be practicing social distancing, my thoughts are with friends and past co-workers continuing to work at the bedside.  

But, here is my question: During the past two weeks I have seen an influx of children sent to my office for mild upper respiratory symptoms. Children between the ages of 5 – 12 have been complaining of a number of symptoms including: cough, runny or stuffy nose, sore throat, headache, and body ache, respectively.  I have not had any students with fever, or severe symptoms that would warrant being sent home, or prompt me to order additional testing. However, everything I am reading and hearing indicates that children are likely to have very mild symptoms, and may even appear asymptomatic. While I do take a moment to provide reassurance, and hand-hygiene and infection control education to each student, I am not worried so much about them when it comes to coronavirus. I am very worried however, for the grandparents with chronic obstructive pulmonary disease, diabetes, hypertension, and other comorbidity that are picking up their grandkids from school at the end of the day. While these children that have COVID-19 are not presenting any differently from common colds, are they able to contribute to the transmission of the virus to more vulnerable populations? Especially as they are not always polite when it comes to their respiratory secretions, and are always touching things.

I am relieved that the schools are closing for the next couple weeks in order to promote social distancing, but also now concerned because many parents will still have to work, and may rely on older adult relatives to provide childcare during this time.

Thank you for the brilliant podcast. I have been recommending it to family members, friends, and coworkers. Keep up this good and important work, and stay healthy!

Best Regards,


Nurse Practitioner

Education Plus Health

Kate writes:

hi~ my apologies if you have already addressed this question, but do you think the reaction/mandates in the u.s. (washington state in particular but it’s definitely spreading (no pun intended!)) ie closing schools, bars & restaurants, non-essential businesses, movie theaters, barbershops, yoga studios, ymca’s, art galleries, libraries, parks, etc is warranted? 

or is it overkill?


Alec writes:

Hello All

First of all thank you for all you do in updating us on the SARS2 pandemic. I’ve been a regular listener to your podcast since I first heard about it when I was working in a hospital in the Middle East during the Mers outbreak. During that outbreak you brought sanity to the discussion and I’m glad to say you are doing it again with this pandemic. Having worked in hospitals through SARS1, H1N1, Mers and all the other “flu season” pandemics in Asia  and the Middle East I’ve seen how much of a strain these pandemics put on any healthcare system and in particular ICUs in hospitals. 

There is a misconception that number of beds in a hospital = number of icu beds. In most hospitals icus comprise less than 10% of the bed total and having to increase or double up on icu beds during a pandemic is not an easy task. Most icus are associated with or located in large academic institutions, very few are in the private sector which avoid them like the plague because of the cost (they are money losers of course) and they are almost non existent outside large population centres. Equipment requirements room configurations of icu rooms are different from normal hospital ward rooms. 

During the Mers crisis we were so short of ventilators we had take old ventilators out of storage and refurbish them so that we could get the extra beds for new patients. ICUs require 1 to 1 nursing and most hospitals worldwide struggle with that on a regular basis let alone during a crisis and nurses require proper training to work there. On top of that not all rooms can be used for icu beds as they don’t have enough power outlets for monitoring equipment, airflow or don’t have the correct configuration for proper infection control procedures. These are some of the challenges countries like Italy are facing in trying to treat people who need icu beds. 

That being said this is the first pandemic where I am not working in a hospital (although I still volunteer in one) and am pretty much on the outside for this one. I now manage condominium towers in the country to the north of you where people are frantically stocking up on toilet paper!

All the best and thank you again


Bob writes:


The first case of someone suffering from Covid-19 can be traced back to 17 November, according to media reports on unpublished Chinese government data.

The report, in the South China Morning Post, said Chinese authorities had identified at least 266 people who contracted the virus last year and who came under medical surveillance, and the earliest case was 17 November – weeks before authorities announced the emergence of the new virus.

Luke writes:

Hey Guys,

Recently started listening to the podcast, it has been getting me through some very long days at work.

Currently a nice 6⁰C, with a few clouds here in Glasgow, Scotland.

Now to my question. Apologies if my terminology or wording of the question is incorrect… I’m not in the field of virology.

Is the possibility of a secondary mutation a reality, could covid-19 mutate to became as infectious as measles or start becoming more deadly to it’s more healthier hosts. If a secondary mutation is possible is there a mutation that is common in coronaviruses that may become evident.

Keep up the good work! Brilliant information.



Paul writes:

Dear Vincent, Rich, Dickson, Kathy, Brianne and other Twiv’ers

Greetings from Hong Kong where currently it is overcast with middling visibility across the harbor, currently 19oC or 66F in old money.

I’ve been a regular listener to TWIV for the past two years, ever since my predecessor as BSO [biosafety officer] at HKU tipped me off about you while he handed over to me. I really enjoy and appreciate both the quality of your content and your successful formula for making the excitement and issues in virology accessible to professionals and a wider audience.

I’ve been working as a Biosafety Officer for more than 10 years and have found I really enjoy it, as you become involved in and contribute to a much broader spectrum of research than you do when you work within your own discipline. And if you get it right you not only help researchers do the right thing, but sometimes the breadth of experience you build up can help them solve practical problems they have outside of safety issues quickly as well.

At the start of the current SARS-CoV-2 outbreak, once it was clear that a coronavirus was involved, I knew that my University would want to think about control measures and some researchers would begin to work on it. Whenever work begins on a new pathogen you have to go to first principles in biosafety to decide broadly what level of precautions people will need to take.  So by way of comparison I looked around for papers about the other already known coronaviruses that have been circulating for years, and came across the following preprint that you might want to discuss on the program.


Prior to the emergence of SARS-CoV-2 this Korean group PCR-screened adults who were ill enough to be admitted to hospital for suspected viral infections for HCoV 229E and OC43. From this they were able to calculate case fatality rates for seriously ill patients infected with either of these two viruses that have been circulating for years. If you assume these two are not just markers for respiratory problems it is an interesting perspective on the potential severity of two respiratory viruses that are not generally regarded as significant risks for some patients. This may help put Covid-19 into perspective if you accept that for these patients these two viruses were the cause of their problems.

Anyway, I would currently advise any deliberate culture with SARS-CoV-2 needs to take place at BSL-3, as it as a pathogen with moderate virulence for many but very high potential for community impact if it escapes, where no prophylaxis or specific treatment is available. Not so different from the situation where a researcher is doing deliberate culture of an influenza A strain (apart from 1918 flu) that has not circulated for many years and is a poor match for the vaccines currently available, although there are some antivirals that I assume would work even for a historic flu.

In eighteen months time or so, when we live in a world where there are now 5 common circulating human coronaviruses, enough people have seroconverted to make transmission unlikely, and we finally have the first effective coronavirus vaccine, there will come a point I suspect when SARS-CoV-2 will be downgraded to BSL-2, joining HCoV- 229E, OC43, HKU1 and NL63.

Keep up the good work,



Paul Hunt PhD,

Biological Safety Officer

The University of Hong Kong

Joyce writes:

Eliud writes:

Thanks for keep it up with the info about the Coronavirus, i got information that companies in Austin,Tx are hiring people to work to assemble the kits that is going to be used for the drive thru and hospital testing for the corona virus. 

also if Cindi in new england needs some gloves or mask i will love to help and send some the department, i work in lab and sometimes we order extra stuff.

Is amazing to hear you podcast and be able to laugh and understand the situation rather then hear the media that thinks they know virus,


Thank you for your time


Luiz writes:

Hi Twiv

My name is Gustavo. I’m a virologist and Post-Doc from University of São Paulo in Brazil working with characterization of Coronavirus diversity in Brazilians bats.

I would like to say that this podcast is amazing and I learn a lot of listening every week. Great discussion and great science. Thank you very much.

I have one question about the fecal-oral transmission route of Coronavirus in bats or in humans.

I would like to know if enveloped virus as coronavirus can be resistant to gastric juice. What is the route of Coronavirus in a fecal oral infection?

The virus should drop into gastric juice and keep it infectivity arriving late to the intestine or 

the virus first infect upper tissues as respiratory tracts cels, make a viremia and then arrive to intestine?

Thank you very much. Keep the good and wonderful work!

Best regards


David writes:

[ad: link to paper on possibly two strains of SARS-CoV-2]

Interested in your thoughts on this article claiming that there are now two strains of the SARS-COV-2 virus


Seems like they are splitting hairs here, two SNPs and no evidence that either is functionally important. The fact that they found in different geographic regions is almost an inevitable consequence of epidemic spread.

So how do we define viral strains?

A related question: now that the virus has conducted 100,000 human to human transmission tests, it seems likely that it may have discovered some mutations that enhance transmission. Welcome to evolution. How would we identify such mutations? Any evidence of functionally consequential mutations to date?



David J States MD PhD

Ann Arbor, Michigan

Frank writes:

Hello All,

My name is Frank and I am a recent TWIV listener, just joined because of the Coronavirus.  I find your podcast very interesting and will become an avid listener even after this coronavirus (COVID-19) settles down.  Anyway, my Before I get to my question, I live in Westchester County, NY. It is approximately 1930 hours on Monday, March 16, 2020.  Temp right now is approximately 39 degrees Fahrenheit and cloudy.  

My question…How likely is it that I will catch COVID-19 just by walking on the sidewalks of Manhattan?  I am hearing/reading that COVID-19 may be aerosolized and linger for some time.  What if someone sneezes or coughs on the street who is infected with COVID-19 and I happen to pass by?  How long would it linger outside in open air and how much time would need to pass to consider that area where someone sneezed/coughed to be considered safe?

Thank you and a great show. 

Frank P.

Fernando writes:

Good Morning Everyone,

Thank you for great podcast and for keeping people informed.

Professor Racaniello, I follow your virology class at Columbia via YouTube.

The question I have is:

Is there a chance a person testing positive for the Flu, mask the possibility that she also has contracted the SARS-CoV-2? I know patients are first tested for the Flu, but I have not heard if patients are then tested for SARS-CoV-2 to ensure they are not infected by two different viruses.

Also, do you have any recommendations for grandparents who are taking care of their grandchildren? My parents are taking care of my nine-month old niece, and we have gone in great detail on procedures to follow in taking care of the baby.

Thank you all for not sugar coating the facts. 


Fernando “Pepe” Navarro

DTED – Initiation Systems Group

Lawrence Livermore National Laboratory

Joi writes:

Dear TWiV,

Thank you so much for your both entertaining and informative podcast. As a teacher at the University of Iceland, it has really influenced how I communicate scientific data to my students.

Here in Iceland we have temperatures a few degrees below freezing and a winter-wonderland scenario of clear skies, heaps of snow and some northern lights.

While Iceland may not be in the news often, except for the occasional volcanic eruption or bank collapse, something very newsworthy has just happened here regarding the Coronavirus outbreak. With a large group of people, including some healthcare workers, having been infected with COVID on a skiing trip in the Alps, and subsequently bringing the disease to Iceland, Iceland now holds the world record for most COVID-cases per capita.

Kári Stefánsson, geneticist who frequently appears in media and head of deCODE Genetics just announced that the company would be launching a free public screening for anyone showing symptoms of COVID19. At first I thought that this was so that the company could compare the infected individuals and their respective virus strains with the company’s vast genetic database, which includes the whole genome sequence, or inferred genome sequence for the whole population of Iceland.

It therefore came as a surprise when Iceland’s Data Protection Authority said in a statement that this screening would not be connected with any data that could be traced to a specific person. We already have the genome sequences of all inhabitants. This means that there is going to be a free and open screening here in Iceland but we will not pair the test results with genome sequences in order to learn more. I am now doubting my morals since I very much feel like this is an oppurtunity wasted to identify some genetic variants that could be important in the infection of Sars Coronavirus 2.

What do you guys think?

Keep up the good podcast. I enjoy every episode of it!

Jói (pronounced YOH-i)

Ben writes:

Hello from San Diego where the current temperature is 69 degrees F, humidity is 39% and wind variable @3kts

Anyway w/ spreading corona I’m just another virology tourist that just happened by to hear the question about re-wearing a face mask in public to prevent being social ostracized (TWiV 590 1:08:54)

Basically given possible shortages due to demand, any thoughts about trying to sanitize a typical disposable N95 mask using UV-C??? Figure 265 nm at 10 minutes per side in a hacked together DYI sterilizer will provide a margin of safety for use @home


Looking at global migration patterns and doing some simple math modeling, seems inevitable the same social distancing and mask wearing that is now the norm in china/korea, will happen here in the so called land of the free, home of the brave (so figure might as prepare best as possible)