> Could You also offer up another TL;DR answer as to why the booster seems to present significantly more side effects? The first one, some of your cells get to

> Could You also offer up another TL;DR answer as to why the booster seems to present significantly more side effects? The first one, some of your cells get told by the mRNA/adenovirus vector (depending on if you had Moderna/Pfizer or J&J/Oxford) to make some 'rona spikes. Your immune system amped up a little bit and your cells feel bad for a bit because of having to spew out spike. Your immune system, which is a little amped up, sees all this and starts to formulate things to kill the spikes (antibodies) and starts to send out other immune cells that clamp down on the cells that are making the spikes. The second shot? Your cells get the call from the mRNA/adenovirus vector and start spewing out spikes. Your immune system recently saw this so it _really_ starts spewing out more antibodies to get rid of the spikes and more of the other cells to get rid of the spike producers. It it is really ready for the fight and wants to make sure you're ready for the fight in the future too. The negative side effects are your immune system causing parts of your body to do things it doesn't usually do (like raising your body temperature to help kill off cells that are making these "rogue" spikes).