[thinkharderdev]

From what I understand it is about affinity maturation. Basically, when you get an initial vaccine (or infection) your immune system learns how to recognize the antigen (the virus spike protein) and produces a bunch of antibodies to recognize it. But your immune system also preserves the spike protein in antigen presenting cells so it can continue to produce antibodies to recognize more features of the spike protein. Over time, your immune system learns how to produce a broader range of antibodies that are (in aggregate) more likely to recognize partially mutated versions of the antigen. That's the affinity maturation part.

So when you get a booster (or a breakthrough infection) your immune system kicks into gear again but now it produces a broader range of antibodies. In addition the number of antibodies produced from the booster is quantitatively much larger than from the first vaccine. So with a booster you end up with more antibodies but also a larger variety of antibodies that can recognize different features of the spike protein (including features that are consistent between variants).

That's my understand at least but I am not an immunologist.

[corin_]

> So when you get a booster (or a breakthrough infection) your immune system kicks into gear again but now it produces a broader range of antibodies.

Would/could it not also be the case for exposure to the virus that doesn't result in a breakthrough infection i.e. the body detects it and fights it off successfully? (I daresay you didn't mean to imply that, just checking.)

[thinkharderdev]

I would assume so but it probably depends on the "level" of exposure and such.