Thread by @sailorrooscout

Immunity is more than just neutralizing antibodies.

Immunological memory consists of antibodies, memory B-cells, memory CD8+ T-cells, and memory CD4+ T-cells. These responses are what give us enduring protection even against newly emerging SARS-CoV-2 variants.

Immunological memory is probably the most important feature of immunity as it allows us to better respond when the threat is encountered a second time. Against SARS-CoV-2, it helps to determine protection against reinfection, disease risk, and vaccine efficacy.

As long as your T-cells still recognize this virus and inform your B-cells they need to get to work and adjust to make antibodies to be better “fit” you’re protected. Imagine your B-cells are your sword that need sharpening every now and again and your T-cells are your shield.

The term infection refers to the virus entering and being detectable in your system regardless of whether OR NOT it makes you sick, whereas the term illness refers to the virus entering, being detectable in your system AND making you sick. It it important not to conflate the two.

Dr. Jansen said it was “very important” that the parts of the Omicron variant targeted by virus-killing cells were mostly unchanged from previous variants. “It gives comfort that you will have sufficient T-cell responses to prevent the worst outcomes.”

While antibodies are the first line of defense against infection, they are only part of a wider-ranging and powerful response by the immune system. Because antibodies are the fastest and easiest part to measure, those results typically come first. nytimes.com/2021/12/08/hea…

“During the first week after onset of symptoms a mild clinical course was observed. This suggests that full vaccination followed by a booster dose still provides good protection against severe COVID-19.” Keep in mind, “breakthrough” symptoms were SELF-REPORTED. SMALL sample size.

More than half the cases were reported as “mild” (think cold-like symptoms), “moderate” (think flu-like). This IS these VACCINES AT WORK. Preventing YOU from facing SEVERE disease and worse. papers.ssrn.com/sol3/papers.cf…

As MORE than 80% of epitopes in the spike protein recognized by CD8+ T-cells are not affected by the mutations in Omicron, two doses MAY STILL induce protection against severe disease.

Out of @settelab: “T-cell epitopes in natural infection? The analysis of the full proteome here show that on average 98% of CD8 and 95% of CD4 epitopes are totally conserved.

https://twitter.com/settelab/status/1469007626306392064?s=21

“T-cell epitopes and vaccination? Here is the analysis of spike-only data. Since many variant mutations are in spike, we expect naturally a higher number of mutated T cell epitopes. On average 94% of CD8 and 91% of CD4 epitopes are still totally conserved.”

“When we get to Omicron presumably because of the higher number of mutations, the fraction of CD8 epitopes that are 100% conserved drops significantly to 95% for CD8 and 88% for CD4 whole proteome. Still very high conservation.”

As always, make sure you are protected. Omicron being “milder” IS LIKELY DUE TO IMMUNITY KICKING IN. Don’t walk around immunologically naive. Get vaccinated. Get protected.
•biorxiv.org/content/10.110…
•theatlantic.com/science/archiv…
•theatlantic.com/science/archiv…
•theatlantic.com/science/archiv…