In addition to the vaccinations, subjects undergo apheresis to collect IVIG once their blood test shows moderately high antibody levels. For this procedure, blood is collected through a needle in an arm vein and flows through a catheter (plastic tube) into a machine that separates the blood cells from the antibodies and protein. The antibodies and protein are collected and the rest of the blood is returned to the body. Subjects are asked to undergo at least three apheresis procedures.