COVID AND THE VACCINE - TRUTH, LIES, AND MISCONCEPTIONS REVEALED, page-91785

The lipid nano particle carries the mRNA to instruct cell to produce spike protein, this lipid nano particle is designed to carry drugs across the blood brain barrier, therefore it does not stay in the arm.
It has been noted that it accumulates in the ovaries and the testicles.
When a cell begins producing spike protein the immune system sees that spike protein as a foreign invader, the immune system attacks and destroys that cell, so if that cell is in the heart muscle that cell is destroyed resulting in scarring and myocarditis.
That is what happens in the ovaries they are damaged, in the brain, neurological problems and so on.