What do you mean by “spread through the bloodstream”?

Of course even in an IM injection, some will end up in the blood stream. The better question is the overall amount that stays within the deltoid vs that that travels elsewhere, and how the compares to natural infection. How does the virus deposit itself around the body vs. how does the spike protein via vaccination deposit itself around the body. As well, with the way the vaccine works, once it hits a cell, that cell will express the spike protein to the surface and that’s it, instead of contributing to further viral spread in the same region.