What parts of the immune system are protecting you against COVID? Immunology is complicated, so here's a graphic to try and explain it.
Layered defenses against SARS-CoV-2, or the “Swiss cheese” model of immunity. Image
Multiple types of adaptive immunity with diverse mechanisms likely provide layers of defense against COVID-19. Conceptually, these are like a “Swiss cheese model”: even though each layer is imperfect, together they keep the pathogen from breaching all layers of defense.
The graphic was inspired by the fantastic masking and public health layered defenses Swiss cheese model of @MackayIM.
The first model is the basic version. This second model incorporates local immunity in the nose/mouth/throat, and circulating immunity in the blood. Image
Multiple types of adaptive immunity with diverse mechanisms and locations. Image
Here's another way I visualize how immunity against COVID-19 likely occurs, across a gradient of disease levels, which take different amounts of time.
I use each of these in my talks. Image
These topics are discussed in the new pre-print on COVID-19 protective immunity here, in the section "T cells in protective immunity against COVID-19"
Thanks to @biomedgraphics for her great graphics design help!

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More from @profshanecrotty

Mar 28
Crotty lab journal club by @P1RAD:
Here is an immunological reason to resist raw cookie dough: Salmonella infection can induce monocytes that disrupt pre-existing germinal center (GC) responses to a primary infection (or potentially vaccines) 🧵[1/5]
Work @ImmunityCP by @AdiBiram, @ZivShulman & colleagues show in a mouse model of Salmonella infection that infiltration of IFNɣ-induced monocytes (CCR2+ Sca1+ Ly6C-hi) from the bone marrow to peripheral lymphoid organs suppress GC B cells [2/5]
The suppression of GC B cells is mediated by TNF⍺ and comes along with disruptions in the metabolism of GC B cells [3/5]
Read 5 tweets
Mar 22
Our new pre-print posted. We compare immune memory to Moderna, Pfizer, J&J, and Novavax COVID-19 vaccines head-to-head. T cells, B cells, and antibody. We think this is the most comprehensive immunological evaluation of these four different vaccines. 1/17
These comparisons are of broader interest, because they compare human acute and memory immune responses longitudinally to three different vaccine platforms: mRNA, viral vector, and protein. 2/17
It has been 15 months of work by a lot of people. A massive team effort! Congrats to everyone involved for their hard work, long hours, and persistence getting this project complete. 🙏🏼 3/17
@SetteLab @Dani6020 @camilahcoelho @ljiresearch
Read 16 tweets
Jan 21
What comes after Omicron? A thorough article with thoughtful comments by @EJohnWherry @deeptabhattacha. I talk about immunity, misconceptions about disease severity, and virology. And my coffee mug analogy about how brilliant your immune system is! 🧵1/4

Your immune system has really been brilliant at recognizing COVID vaccines & evolving immune responses that not only recognize the Spike in the vaccine, but also made educated guesses about what variants may look like—even though your immune system didn’t get to see any variants!
““It’s like you showed the immune system one kind of coffee mug, a round thing with a handle, and from that it was able to recognize every kind of mug that you can imagine. It’s remarkable.”

With 2 doses of vaccine, your immune system could recognize a wide range of variants…
Read 4 tweets
Dec 27, 2021
1st thread on our long germinal center (GC) preprint was last week. I promised a 2nd to dive into more of the biology:
Do naive B cells sustain long GCs?
Do GC cells have clonal migration to other lymph nodes during an ongoing GC?
Do low affinity B cells compete in these GCs? 🧵
1/ Do naive B cells sustain the long GCs?
With the long GCs lasting over 6 months, are the same B cells active in GCs for that long? Or do they 'graduate' or expire after a shorter period and get replaced by entirely new clones?
Read 23 tweets
Dec 22, 2021
Our newest study reveals some surprising immunology, which is relevant for vaccines.
We immunized animals with a protein vax and waited to see how long germinal centers (GC) would last. Expectations were GCs would peak by 3 weeks & be gone by 6. How long did they actually last?🧵

Vaccine-binding GC cells PEAKED 10 weeks after immunization.

So we waited....

Still going at 13 weeks
Read 26 tweets
Dec 8, 2021
3 studies today on antibodies & Omicron.
🔵 There may be a large drop in neutralization of Omicron
🔵 Antibodies stop Omicron well in hybrid immunity (infected+vax)
🔵 Sotrovimab is active versus Omicron

Take home: Get vaccinated. Get boosted. Immune system is clever. 🧵 1/n
Live virus neutralization preliminary data from @Sigallab in South Africa found a 41x drop in vax neutralization of Omicron. That is a large drop. Seeing hybrid immunity do much better is encouraging. Average Omicron neutralization of ~1,000 was good (>vax neut of WT). 2/n
Neutralizing breadth in hybrid immunity is outstanding. And we know that 3-dose (boosted) vaccine partially recapitulates that improvement in breadth. 3/n
Read 21 tweets

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