A lot of jws do know that vaccines are made with blood, but somehow dismiss it in their minds. Maybe because the amount is so small it is no longer blood? Their crazy idea-not mine!
The rhogam injection given to mother's after delivering an RH positive baby when they are RH negative has been a conscience matter for decades with the jws. I knew two fleshly sisters who were jws and one decided to accept it and the other refused. Neither had any problems, thankfully, as they each had several children. The one that refused, however, was putting her infants at great risk.
If you look up the rhogam shot, it will actually tell you that it is made from blood plasma. It will also tell you because it is made from plasma, it carries certain risks of transmission of disease.
I remember an article asking whether jws could use pet food that contained processed blood. I believe the answer was no. You can't get much crazier than that! Don't animals eat each other? Do they drain the blood first?