This is, of course, if you do not contract a blood-borne infection from that exposure. I am worried about contracting a disease from donating blood. Sterile, single-use supplies are only used and then discarded after use. The arm is prepped with an antiseptic to also prevent infections. All phlebotomists, to prevent the direct contact spread of microbes, wear gloves.
Blood transfusion is very safe today with a very low risk of infectious consequences.
In certain situations, a person is able to donate the blood units for themselves and set it aside in the Blood Bank Department in the event they need a transfusion. This is called Autologous transfusion. Some individuals are not able to donate their own blood and can request Directed blood donations. This is where the patient asks donors to give their blood and set it aside for the use of the patient in the event they need a transfusion. You do need to know that Autologous and Directed blood donations need physician orders.