A daily vitamin usually has insufficient amounts to do enough good. I have compiled suggestions at
http://www.thalassemiapatientsandfriends.com/index.php/topic,4890.msg46774.html#msg46774These are adult doses, so adjust for the child's age and weight, usually 1/4 to 1/2 of the adult dose. Most important are components of red blood cells, like folate and B vitamins and antioxidants, especially natural vitamin E. Avoid any supplement containing iron, unless iron deficiency is also present, as indicated by a full iron panel of tests.