T Cells; Precision and Accuracy; Immunity Debt
After the line below, I’m sharing an email I wrote two days ago on a private email list. The intent of the email was to share a few references about T cells, but to do that, I felt I had to write up a short (and hopefully useful) rant about precision and accuracy, and also mention “immunity debt” (which is a BS term, as far as I know).
As I said, I expect to be sending more posts to Pete's COVID-19 News for a while, with some of them being more specific and perhaps less generally interesting. Feel free to skip the messages that aren’t of interest to you. Also apologies, soon after this email, I have another T cell thread to share, with some other links.
A reminder, if you know someone who might find this list useful, you can send them a link:
Thanks for reading. Stay healthy!
I'm here to share a few references to T cell research; but in contemplating how to answer, I started to muse on this:
It is not simple to talk about a complex subject.
T cells (which come in CD3, CD4, and CD8 flavors) and their role in immunity is not a simple subject. Your immune system and how it works is not a simple subject. Whether your immune system is killing invaders or targeting your own body's organs (auto-immune disorder) is not a simple subject. The role of your gut biome vs. the role of your lymphocytes in managing your immunity is not a simple subject. So on and so forth.
T cell research -- who is doing what, what they are reporting, how the consensus understanding is changing from month to month, how T cell disorder might affect your immunity, whether it's short-term or long-term, whether it's happening to long COVID people, or to anybody who gets COVID -- none of that is simple.
And then, the whole T cell discussion, which is important, is but a tiny sliver of a much larger galaxy of the things we could talk about with respect to COVID and societal implications.
Allow me to switch gears for a moment to talk about precision vs. accuracy. This is a concept you learn when you get a little older, that humans conflate the two, and that you need to be consciously mindful to make sure you don't.
An easy example of precision is the number of significant digits in a decimal number. If I say something is 1 centimeter long, how do we know I didn't round up from 0.6 or down from 1.4? Well, of course, I can just say it more precisely: I really mean 1.2 centimeters. It's recursive, though; in saying 1.2, did I round up from 1.16, or down from 1.24?
Okay, fine. I measured it carefully with my ruler, and what I really mean is 1.245473928 centimeters.
Except that's a lie, and hopefully it's pretty easy to guess that it is. My ruler (you might guess) is marked in millimeters, and so while I can tell the difference between 1.245 and 1.246 centimeters, I certainly CANNOT tell the difference between 1.245473928 and 1.245473929 centimeters.
And yet, if you didn't know about typical rulers, that they often measure in millimeters but not nanometers, you might assume that because I have been very precise to say 1.245473928 centimeters, it must also have been very accurate. Which is completely wrong; it's not accurate at all.
I feel sort of the same about sharing a few small, precise pieces of information (a scientific study) about T cells. It's precise, but not necessarily accurate when read by various readers, and to be accurate, we have to talk about a lot more things -- that particular study, other studies about the same issue, meta studies about the topic, who the authors are and where the study is published, whether it's a pre-print or not, who reviewed it, who has read it and what they think about it, whether I trust or distrust those readers and their opinions, etc. Not to mention the fact that while important, the T cell issue is a small part of much larger and much more complex set of issues.
It turned out that I didn't feel I could share any reference without taking a couple of hours to write up a separate document (What I Tell Friends About COVID in December 2022, also previously shared in Pete’s COVID-19 News) that was zoomed way, way out, written in plain language, that said what I felt was a reasonably accurate picture of the most important things I believe about COVID right now. And sacrifice a TON of precision in the process, because I could choose either precision and an inordinate amount of time and article length, or reduced precision, hopefully more received accuracy, and a manageable amount of time and article length. (A tiny tiny example of one kind of precision I sacrificed in the name of plainness of language: I call SARS-CoV-2 the “COVID virus”. Does that make me a good communicator, or a bad one?)
Okay, let's start getting around to sharing some references. Luckily for us, someone tweeted a good thread about T cells and immunity. Although, to share that, I need to explain a little about the concept of “immunity debt”, which is causing a stir in the medical, science, and public health realms right now, and which is the reason for the poster's thread.
The idea of “immunity debt” is that we haven't been getting sick for a year or two because of masking and social distancing, and so our immune systems have gotten a little lazy from not being challenged enough. According to the immunity debt believers, that explains why kids in the US and elsewhere are having a rougher time right now with RSV, influenza, staph A, etc. — immune system laziness.
The experts I believe say that “immunity debt” is BS, that kids are getting sick and sicker with RSV, influenza, staph A, etc., because ~75% of them have had COVID in the past year, and that they're more susceptible to disease because COVID trashed their immune systems.
“The immune system is not viewed as a muscle that has to be used all the time to be kept in shape and, if anything, the opposite is the case.”—Deborah Dunn-Walters, professor of immunology at the University of Surrey, via ‘Immunity debt’ is a misguided and dangerous concept - Financial Times (free to read) (2022-11-22)
(To complicate matters, I think there are different meanings people ascribe to “immunity debt”. What I described above is the meme-level meaning of it; other minority meanings may be more or less bullshit. So there's that complication to the debate as well.)
Finally, the T cell references I wanted to share, starting with this thread:
Which leads to (among other things):
“Reduction and Functional Exhaustion of T Cells in Patients With Coronavirus Disease 2019 (COVID-19) - PubMed” (May 2020)
“Activation or exhaustion of CD8+ T cells in patients with COVID-19 | Cellular & Molecular Immunology” (Aug 2021)
“Dysfunctional State of T Cells or Exhaustion During Chronic Viral Infections and COVID-19: A Review | Viral Immunology” (May 2022)
That's precise.
Is it accurate?
Who knows?