The function of iron the body's ability to fight infection is very tricky. With thalassemia, either minor or major the role of iron in the body is different than non thals. From what I understand, healthy iron stores make your immune system strong, but too much loose iron in the blood impairs infection fighting. Remember that iron goes through may phases in the body, loose, ferritin and transferrin. I avoid taking my iron supplements when I am fighting an infection, but if my ferritin is high I get much fewer infections and colds.
As for surgery healing, I heal slow and get complications all the time...