Hooray, I am finally boostered! I did not mind what I would get, but ended up for the 3rd time getting the BioNTech/Pfizer mRNA vaccine.
I received some feedback concerning this 2-sentence blog post. I never really think much about the vaccination anymore. To me, the situation appears very clear from a science-based medical perspective. Below, I will keep adding answers to some questions and statements.
But there's another angle to this: The fact that pushing the antibody response might lead to a spillover from the IgG-dominated response to the production of some IgA antibodies. Whether all of these antibodies are de-novo responses or whether some result from switching of antigen-experienced cells (from IgG to IgA) is unclear. Theoretically, such a switch would be possible to both IgGa1 and IgGa2 because the necessary DNA sequences are still available downstream aven after the initial class switch. From IgG1 and IgG3 the switch would be possible to both IgA1 and IgA2; from IgG2 and IgG4 the switch would only be possible to IgA2.
In any case, even though not dominant, there are also IgM plasma cells and IgM memory cells, which could theoretically undergo a class switch. The same is true for hypermutation. Although these cells can hypermutate they mostly do not hypermutate (or at least not much). Instead, they maintain a lower affinity and therefore a broader reactivity, resulting in a specific capacity to cope with variant forms of pathogens, which might induce them again to undergo further maturation in germinal centers.
I have no clue which of these scenarios is playing out in SARS-CoV2 infected humans who have been primed three times by the mRNA vaccine. I assume that nobody really knows, but exactly the fuzziness of the immune response is what makes it resilient towards any type of challenge. I trust my immune system to be fuzzy and smart enough to react to the 3rd shot with a variety of heuristic strategies that have been proven in the evolutionary past to mostly work.
* In addition, Delta has one 2-aa deletion compared to Wuhan-Hu-1, and Omicron has one 2-aa-deletion, one 3-aa-deletion and one 2-aa-insertion.