In response to my question of where are they injected. :
Intramuscular or subcutaneous injections have the same result. The needle end is either inside a cell, or between cells. If inside, the vaccine will be deposited inside the cell and cause it to rupture, spilling the vaccine between the cells. All living cells are fed by the capillary system, therefore the vaccine goes into the capillary system, then flows into the circulatory system. Specifically, into veins, to return to the heart.