Anne writes:

Hello “my” virologists, 

I have been unable to find a CDC recommendation about singing again. My chorus Director is suggesting we gather and sing outside. I live in western Massachusetts where we have a high rate of vaccinated people. I would really love to get together and sing again, but I would appreciate hearing from you all whether or not we should.

In conversations I have come to refer to you as “my” virologists after listening to your podcast for so many months. I’m very grateful to have scientists to listen to. Thank you.


Chris writes:

Hi TWiV Team:

It’s a balmy 95F with high humidity and a heat index of 101 here in Atlanta, Ga.

As I’m sure you’re aware, the CDC has changed its guidance on masking, recommending that even fully vaccinated individuals wear masks indoors in areas of the country where community transmission is “substantial or high.” This is in response to evidence suggesting that viral “loads” (based on Ct) are nearly the same between breakthrough infections of vaccinated individuals and the unvaccinated, which in turn would imply that a vaccinated individual is just as capable of spreading the virus as an unvaccinated individual. At least that is my understanding– I don’t have any sources to cite unfortunately as this information was just presented in an internal webinar.

After hearing this I kept thinking back to what is often discussed on TWiV where we just don’t know how Ct correlates to infectivity or “viral load”. As a humble biochemist focusing on synthetic DNA, I must admit I don’t quite understand how this all fits together. Would any of you be able to explain how it is that Ct values wouldn’t necessarily correlate with the amount of infectious virus in an individual? I think I recall Vincent saying something along the lines of  “a variant that can throw off more RNA.” Would this mean the virus is carrying multiple genome copies or that it’s multiplying faster? In context of CDC’s new masking guidance, would it be possible that just because a vaccinated individual has a similarly low Ct value as an unvaccinated individual that the vaccinated individual is not equally able to transmit infectious virus? If that’s the case, I suspect the CDC is erring on the side of caution since, as you all have pointed out, there just haven’t been infectious virus studies.

Looking forward to your response! Thanks for all you do keeping us informed and sane amidst the flood of emerging information.


Andrew writes:

Thank you so much for this podcast. I’m writing from Atlanta where the heat index is supposed to be 104 degrees today. Over the last year the Clinical Updates have been very helpful for me and my family in dealing with Covid and giving us confidence in the vaccines. The methodical and logical way of presenting research and data – good or bad – is a breath of fresh air from the Facebook doctors and random people with an opinion and has been a good way to explain Covid and the vaccines to other people.

I completed my Pfizer vaccination in March. A week ago I had a headache for four days and some fatigue but figured it was sinus related. Ironically, my five year old daughter was also sick at the time with fever and congestion, and I took her for a Covid test and also got one myself even though I was starting to feel better. She was negative, but to my surprise I was positive. I have since had two negative tests and feel much better. The doctor thinks my viral load was heavy during the time of the headaches and was enough to trigger the first positive PCR test. 

My question is that now that I’ve been vaccinated and also had a breakthrough Covid case, do I have an even greater “super immunity” and stronger antibodies? Am I more protected from Delta now than before? Are the antibodies variant specific – meaning are they only going to be effective on Delta and less effective on Omega?

Thanks again for all your help.


Bill writes:

Thank you for TWiV. 

I started listening to TWiV for accurate information about the pandemic.  I continue to listen to the non SARS-CoV-2 viruses too.

I do not mind when you also talk about other things.  When you get into the depths of viruses, a tangent into planes or whales gives my overwhelmed brain a chance to recover a bit.

I also do not mind if you get “political.”  I do object when the politics podcasts (or economics or….) start talking beyond their understanding about viruses.  

But I know that I can relax, wait a few days, and get the straight scoop from you.



Sue writes:

Hi TWIVstars

About 6 weeks ago, I had an RSV vaccine. 

We seem to have a few trials running here, and I’m one of the guinea pigs for the version for older people.

Like a lot of people, I’d never heard of RSV until hearing about it and the early RSV vaccine attempts on TWIV.

When we opened our borders to quarantine-free travel from Australia we imported their RSV, and it’s rampant here at the moment.

My participation is thanks to TWIV, and thanks to TWIV I’m not sick right now.


Michael writes:

Dear TWIVtastics,

I was delighted to see Vincent Racoon Yellow on the thumbnail for TWIV Episode 786. I’d worried that I’d offended Vincent with that graphic of how my Amazon Echo devices parse his name. 

Anyway, I’ve got an actual virology question. My son, who is fully vaccinated (with the Pfizer vaccine), has gotten sick twice this summer since coming out of his pre-vaccination isolation with some viruses that produce cough, sore throat, and congestion (but, by PCR testing, are not SARS-CoV2). When thinking about the coming school year, he wonders whether it would be better to mask at school so as to avoid illness of any kind or, alternatively, to stay unmasked so that his immune system will be periodically challenged. He’s concerned that isolation over the last year has resulted in an immuno-quiescence that leaves him vulnerable to every virus that passes his way.

So my questions are: (1) Is my son justifiably concerned that his immune system will weaken if not challenged by the normal array of pathogens to which the unmasked are exposed in a school setting? and (2) Even if his concerns are justified, is it best to remain masked (when in school) so as to help slow the spread of SARS-CoV2?

Thanks for your collective input on this, and thanks for all of the great information you’ve shared with us over the course of the pandemic.