Martin writes:

Dear TWiVers

It seems as though the UK is just beginning to catch up with Michael Mina a little with its 90-minute PCR. We just need one in every household now…

Best wishes


Craig writes:

I love your podcast. It’s a delight to learn about viruses and immunology. I listen to each episode several times and pick up more on each pass. I’m “just” a computer consultant, with a background in mere mechanical engineering, but your discussions are enlightening and fun too!

I’m sharing a letter I wrote in support of the testing paradigm shift promoted in episode 640 with Michael Mina. Please share this as a possible template.

A couple points I haven’t heard emphasized widely:

– “Fast, Frequent, Widespread” sums up the most essential qualities. (A mnemonic for those of us who are old enough to remember the markings on tape decks: “FFW” will let us Fast-ForWard to the end of the epidemic!)

– Being self-administered is highly desirable. Trained people and lab capacity are painful bottlenecks.

– These tests could be administered at the door as spot checks to allow admission to buildings or events.

– These even overcome privacy concerns. The tests don’t have to be sent to a lab, the results don’t have to be shared, and anyone who is concerned about privacy issues can even destroy the sample themselves.

Thanks so much, keep up the excellent work!


Tony writes:


This is for TWIV.

There twice was a virus named SARS,
The second of which closed the bars,
Some said it’s just flu,
But the rest of us knew,
It’s a serious pain in the arse. 

I am British and “arse” is the British English version of “ass”.

Love the show, 


Matt writes:


I am a lay person with no background in virology or immunology, but I love the show and have learned a lot.

Do these SARS CoV2 seroprevalence studies also look for T cells in addition to antibodies?  I have read recently that some percentage of people have been infected but don’t show much or any antibodies afterwards.  One theory for the number of asymptomatic is that many people have memory T cells from other Coronaviruses that arrest the disease early before resulting in symptoms.  If that is true and seroprevalence studies don’t look for these memory T cells, couldn’t the seroprevalence studies be underestimating the actual infection rate in the population by 50% or more?

I was thinking of this after New Zealand announced new cases after “102 days of no community transmission”.  There either are a lot more asymptomatic cases then we know or there is another reservoir (e.g. cats).  Please let me know if this thinking is incorrect or just not supported by evidence at this point.

Thank you for your time and keep up the great episodes!


Andy writes:

Dear Vincent,

I enjoyed the TWIV coverage of the Georgia outbreak. Two things. First the key to this is that they allowed the older student counselors to all be vectors to then bring it to the cabins with the kids. You basically had one (or more) super spreader events for the older kids who then spread it to their cabins. There is no evidence that the little kids spread it because the camp closed too early.

That brings up the more important point. We are sitting on the most important data set for school reopening because we have little kids who almost certainly got sick before their parents. So if we can figure out the attack rate from those kids to their families. You mentioned this briefly, but this question is worth billions and billions of dollars. Why don’t we call them and ask and publish it this week?


Kristen writes:

Dear Twiv, 

Thanks for all you do. I love the show! 

I just wanted to chime in and say that I had a Covid test performed by the County Health Dept. here in Portland, Oregon on July 27, and I am STILL waiting for my results on the morning of August 11. They are running 12-14 days on test results! I isolated until my symptoms were long gone — I took the Johns Hopkins Coursera course in contact tracing, so I knew from my training how long I should wait to enter public spaces with a mask, but how many of those people in line behind me did the same?! I knew the tests were taking a long time, but I’m still shocked. 

Just wanted to get this information out there. 



Cynthia writes:

Greetings from Germany, 

Thank you so much for the work you do on this show. It is a vital public service!

Can coronaviruses pass into the brain in patients who have had head trauma via the blood-brain barrier? I came across a few studies that made me worry about possible brain involvement that occurred too early to be a result of low blood oxygen, such as loss of smell and taste. I am also wondering if the higher death rate of some ventilated patients is due to issues with the brainstem, rather than lung damage. I have read that SARS could get into the brains of lab animals and would welcome any literature recommendations. I’m not a scientist, but I have had to undertake a lot of research to learn more about hemiplegic migraines and complications after a nasty concussion. 

The New York Times published an article on suspected neurological involvement, but it didn’t have too much information. I realize you can’t definitively say yes or no as we are still learning about this virus, but is it in the realm of the possibility that people with a history of head injuries have a slightly higher risk for neurological complications? Should we be considered high risk? Would it be worth asking about this part of patient history to help determine if they could become a severe case?

On a side note, we are jokingly thanking our greyhound for performing Covid-19 tests every time she farts. I haven’t lost my sense of smell, yet!

I hope you and your families are well.


Cynthia Dretel, MA

Doctoral Candidate at the Musicology Department of the Hochschule für Musik Franz Liszt, Weimar.

Marie writes:

Hello TWiV team,

I’m a biology instructor at an international university in Cote d’Ivoire (Ivory Coast), West Africa. Thought you’d be interested on how the pandemic is being handled here. 

For some background, about half the country’s population lives in the main city of Abidjan. There seems to be a large Chinese community, as well. Our university is located in a town outside of this city, about 45 minutes away by public transport. Most of our students live in the city and take public transportation or our university buses.

On March 13, there was one case. The US was having serious discussions by this time, and we were on our three day spring break. When we returned there was some talk about COVID19, but everything was business as usual. 

Monday the following week, the 20th, the day began normally. By 10 AM students and faculty were told to get FFP2 respirators and wear them. Some students did. One or two wore them correctly. By about 4PM, we were informed that a task force had been created and would meet the following day to figure out the best response of the university to the crisis. By 9 PM, classes for the next day had been cancelled; the government had issued a notice closing all schools for 30 days, putting in place handwashing measures, closing parks, etc ( Restaurants and bars remained open. 

By Tuesday evening, the students were told to leave the university by the end of Wednesday. As we are an international university, I know that some students and faculty had traveled and became ill upon returning (I don’t know what the test results were). 

It was eventually made clear that courses would resume online. Now, the connectivity to internet here is not suitable to online courses. We weren’t sure which of our students even had internet access.

On Friday afternoon, we were told not to come to the university the following week; it would be closed. 

This week, we are back at the university but on rotating shifts.

Within the past week, the government has limited travel from Abidjan to the central and northern parts of the country, closed the borders, carried out some sanitation measures (what DO they spray when they are spraying the streets?), set maximum of 50 for gatherings, limited number of people in the vans used for public transportation, closed bars, set a maximum price of hand sanitizer, and carried out a MASSIVE public awareness campaign, set a curfew from 9PM-5AM, among other measures I’m probably not aware of (my French is lousy). 

I’m really impressed. The streets are lined with signs showing people how to prevent spread of the virus (showing, since the literacy rate is low), businesses require prior to entrance handwashing from buckets set up in front of the shops which contain a mixture of soap and water, taxi drivers and shop owners wear gloves and sometimes masks, the number of clients inside a shop is monitored and limited, lines outside the shops/at banks/in pharmacies are spaced out, we receive frequent text messages with tips and emergency numbers. 

The other day I went to a pharmacy for malaria prophylaxis, and they had spaces for clients marked in tape on the floor. Some businesses temperature-check you before entry. 

A couple things make it easier to cope here than in the states. Supermarkets are rare where I am, and it’s much more popular to go to a ’boutique’, which is a small shop where the goods and the owner is separated from clients by an iron grid. You ask for what you want, and (if they have it) they hand it to you. Easy purchases while maintaining  physical social  distancing. Fruits and eggs and a few other small things are sold at roadside stands which are rarely crowded. 

If you’re wondering what sells out in the grocery stores: Pasta, tomato paste/sauce, hand sanitizer and liquid soap, canned sardines, flour, dry beans. There is still toilet paper and bottled water. 

On the other hand, people are people and there is plenty of virus denial and informal gathering. People by custom cluster close together in large groups. People are also on average more social than I’ve observed in the US and in larger groups.  Few systems are set up for remote work or services, since credit card fraud is high and internet connection is poor. I still need to travel to the city to pay my rent and still need to get cash to pay water and electricity. Vendors on the street are selling surgical and cloth masks, made and stored in who-knows-where. Also, to get most vegetables I need to go to the market, which is almost always crowded. Electricity is not reliable. Water is not reliable. People still use public transportation, because they have to. And of course, the hospital system is not prepared to handle a ton of patients if this takes off. 

And although it seems a small  thing, living on your own in a tiny apartment and teaching online classes are a bit harder when your connection is too poor to watch Netflix or use Zoom! (I upload my lectures onto YouTube when I can– they seem to have this figured out). 

Today, April 2, there are 179 cases, 11 more than yesterday. We are not yet in the exponential growth stage. 

You can find additional information here if you speak French: 

I do have a question besides what are they spraying on the streets: do eyes play a role in viral entry and infection? For example, if you are wearing an N95 mask and someone coughs in your vicinity, or you touch the corner of your eyes, does the virus efficiently take hold from that route? 

Thanks so much for your information! Stay safe. 


CC writes:

Aloha ~

I work in a school here in Honolulu with after school and summer school programs.

Our schools closed on March 19th and the stay-at-home/work-at-home order was put in place on March 25 until April 30.

From looking at this projection on the link above, it looks like Hawaii’s infection curve will peak on or near May 5 or 6,  with the decline continuing till the beginning of July.

As you may know, educators plan, coordinate and then, implement.  This is our work cycle. Some have been planning since October for a successful summer school program. But from a public safety and security stand point, is it best for schools and other community organizations in Hawaii and across the country to cancel our summer school programs?  Is it realistic to think that we could run a summer school program starting on June 8 or would it be better to plan for a July 1 start up or skip the program all together this summer? 

On a personal level, I still do not fully understanding what happens to our state/country once these stay-at-home orders are completed. Yes, I get that we can freely go here and there and continue in the patterns of our former life, before this pandemic. However, until a working and approved vaccine in place for this virus, won’t the virus still be around? So is it realistic for us to think that life will be back to “normal” until there is a vaccine? Or should we realistically be thinking in terms that until there is a vaccine, we may have times when our country/world are under stay-at-home orders again in the next year to 18 months until a working, tested and FDA approved vaccine is in place? 

I am new to your show and have only listened to three podcasts and have enjoyed the content. I hope that you will take the time to answer these questions. Thank you.


Chuck writes:

Would there be any value of noting results of smelling a scented candle at regular intervals throughout the day as a crude early warning indicator of Covid19 infection onset?

The rationale being that if virus shedding is minimal at the earliest stages of infection, one could then preemptively isolate oneself from loved ones at this critical time.

Thank you, Chuck, Pastor, LaGrange GA

Joe writes:


I’m thoroughly enjoying your solid scientific discussion on some deep topics, thanks so much for doing what you do.I have a question

Q: Given that we see COVID-19 patients present initially sometimes with gastrointestinal issues, sometimes with loss of sense of smell and sometimes with a milder dry cough could these three disparate initial presentations reflect where the initial SARS-CoV-2 infection occurred? Hand to mouth (gastro), hand to nose/virus breathed into nose (NP/smell) or more generic lung inhalation (dry cough). I know most bad cases end up with very bad coughs/pneumonia but I am very interested if these initial presentations mean anything about how the virus might be spreading. Or maybe it means nothing and its just how the patients immune system responds.

I would be very interested to hear some opinion on my idea. I am an engineer and not in the medical professionals at all. So maybe my idea doesn’t add up.

Really enjoying your podcast! Stay safe.

Kind Regards,


Ken writes:

Regarding the recent discussion of whether the number of virus particles influences the severity of the symptoms there was the claim that it was impossible to get data on human infections. 

This week’s NewYorker had this interesting article about virus load that includes

Then they measured how much the women shed a virus called HHV-6, which is usually spread through oral secretions to an infant after birth, and which causes fever and a red whole-body rash. It was now possible to investigate how the amount of virus-shedding—the “dose” of exposure—affected the likelihood of a newborn infant becoming infected. Gantt, Mayer, and their colleagues had devised a way to eavesdrop on the dynamics of the transmission of a human viral infection from the very start. “Our data confirmed that there’s a dose-response relationship in viral transmissions for HHV-6,” Mayer told me. “The more virus you shed, the more likely you are to infect others.”

Yes, every virus is different but I thought this was relevant. 

Lené writes:


I’m a new fan of your show. Thanks for making the content accessible for non-medical professionals. It’s a joy to listen to and learn from you all. 

My two questions are about disinfection techniques. 

1) There have been videos and photographs shared online of truck and backpack-style fogging machines used in China and Iran to disperse disinfectants in response to the recent pandemic. I continue to read that this coronavirus is not airborne (except following medical procedures that release aerosols). Do you know why these countries would use fogging machines for disinfection if the virus was only a concern on surfaces?

2) Do you think this method of disinfection would be helpful in the US? (I haven’t seen any reports of it being used here.)

Thanks for your time and any thoughts you have.



Montpelier, VT

Good evening, I have seen a video circulating online explaining how viruses can’t actually be spread other than being injected into your bloodstream? 

I have posted the video below.

Can you tell me if this holds any water?

Kind regards, 


Alex writes:

Dear Twiv,

On March 23rd the Swiss authorities put police tape on the playground equipment in my local park here in Geneva.  (see photos)  Ping Pong tables were spared until yesterday, March 31st, but basketball courts are still open.   Is this just an abundance of caution or do have any basis, especially the specificity  (basketball good, ping pong bad)?  



Charles writes:

It is sunny and beautiful here in Toronto despite being quite nippy still at 3C. Luckily I can admire the day tucked away in my apartment without any incentive to otherwise brace the cold.

I have been unsuccessful in trying to find a solid answer for the subject question so I thought I’d ask here: can the force generated by sneezing cause aerosolization of exit particles during the sneeze?

In any event, keep up the great work! I feel like 99% of the useful things I know about all things related to the current outbreak originate from your show and it has helped me give quality advice to the people around me.

Alyssa writes:

Professors and Scientists of TWiV,

In December I flew from PHX [Phoenix] to SEA [Seattle] and came down with what I thought was at first the mild flu despite being vaccinated. I did experience diarrhea first, then fever, sore throat, extreme lethargy, SOB, but I did self-quarantine for over ten days. Yet once the fever lessened I still had respiratory problems. I went to the ER in Wa state, they tested me for the common flu and was tested negative. They diagnosed me without positive results from an x-ray of bacterial pneumonia. I still felt lethargic and SOB when I returned to PHX and went to the ER here. They said it was probably the cold yet despite telling them I had body aches and all the classic signs of the flu. Is there a place I can test to see if I have antibodies? The CDC website is beyond inundated and my county’s  (Maricopa County) website is down. 

P.S. Thank you for providing accessible information and your contribution to the healthcare and microbiology field. I made the switch this year in the middle of nursing school to go after my true passion for microbiology. Thank you for the inspiration and reassurance I am not the only one who has struggled to find their right fit into contributing to the scientific community. Wishing you all the best.


Tom writes:

This may not be in your purview, but maybe one of the doctors you know could speak to whether this could work:

Could chambers be built to hold one person and have the air outside increased, and would that increased air pressure do any good at helping the person to breathe? I have no clue if this is even feasible

Pete writes:

Hello Dear Hosts,

I hope someone already notified you that TWIV was recommended by Leo on TWIG 552. Which raises the question, Did TWIV get the TWIG bump?

Confession time: I have not been following TWIV much due to time constraints; I have been listening to all the TWIPs and TWIMs, however, which are easier to comprehend with my completely non-bio background. 

Also, huge Dickson fan. Amazed how he asks such smart questions on TWIV, when he’s the only non-virologist. I guess by now he should be considered for an honorary degree. 



TWIG = This week in google

Part of TWiT This week in tech  

Jessica writes:

Hi Vincent and the rest of the TWiV Team,

Thank you for ramping up your TWiVing to keep us all up to date on the pandemic! As a structural virologist, I wanted to help clarify something you discussed on a recent episode. You touched on engineered coronavirus spike proteins that have the potential to be used in a subunit vaccine. The innovation here is actually quite interesting. The coronavirus spike protein is what we call a class I fusion protein, and this protein undergoes a massive conformational change in order to facilitate membrane fusion between the viral membrane and the host membrane. In the pre-fusion state, the center of this protein machine holds three alpha helices that are bent in half and resemble little spring-loaded hairpins. Once triggered, presumably by binding the ACE2 receptor, this hairpin will straighten out into one very long alpha helix. This, coupled with some other re-arrangements and cleavage, results in the post-fusion form. 

As you pointed out, it is important that vaccines based on the spike protein only contain the pre-fusion form as it is unlikely that antibodies directed against the post-fusion form would be protective. The innovation to stabilize this pre-fusion form came from Kirchdoerfer et. al. in 2018 (link to article below). This group engineered in two proline residues right at the apex of the hairpin making it very difficult for this helix to straighten out into the post-fusion form. These two mutations were incorporated into the constructs used for the recent cryoEM structures of SARS-CoV-2 pre-fusion spike protein and are likely being incorporated into vaccine candidates. 

I hope that helps and do keep up the good work!


Jessica Bruhn, PhD