All blood is screened, they can't just take your donation then fuck it in someone els and believe you told the truth.
There was a big deal here in the uk with hep b in the 90's i am sure it was or late 80's in to the 90's It never came to light until several years ago and it was contaminated blood given to ppl during transfusions. Back then it was not screened but severely is now.
So there would be no chance or very difficult to get contaminated blood giving to you. Well we hope.
I donate every three months i have missed the last two -three as my haemoglobin was high so they refused me. I am on TRT and it has this on my slip and i am passed to donate.