Yeah I had my booster awhile ago and it did nothing, in comparison had absolute shit time with the second shot though, malaise, extreme myalgia, 102+ temp for 2 days, rigors, lymphadenopathy where my draining cervical lymph node was the size of a golf ball for weeks, good times yet I did it again with all that being a chance.
I do have a hypothesis that it’s not just strictly immune related, though that plays a huge part and could also be related to whatever your body is constantly engaged with at that time (you are in a constant state of “infection”). Instead I think it’s somewhat dependent on efficiency of RNA uptake, cell type, and current replication capacity of the cell. There’s no controlling that with the vaccine and the reason why dose response is pretty randomized across the board.