The spike protein coded for in both types of vaccine is designed to remain anchored to the cell wall with it’s antigenic bit presented to the outside. It isn’t meant to be released into the extracellular space. This is why people got excited by the research finding picograms of bits of spike protien free in blood post vaccination. 1 pico gram being one trillionth of a gram. Any forgign protein will caise some degree of immune response. Like a blood transfusion reaction. Apart from ABO there are scores of other proteins on red blood cells all of which could cause a transfusion reaction to varying degrees.