There are many natural proteins in your body with a gene sequence similar to the spike protein. So the antibodies you make against the spike protein will attack your natural protein in the organs of your body.

The antibody for the spike protein attacks Syncytin which creates and maintains the placenta in women. In men, it's involved with sperm production.

There are about 80 natural proteins in the body with a gene sequence similar to the spike protein. So the antibodies you make against the spike protein will attack your natural protein in the organs of your body.