HIV has been transmitted via transfusion of single-donor blood and blood products, including whole blood, fresh frozen plasma, packed red blood cells, cryoprecipitate, clotting factors, and platelets. Prior to May 1985, when the Red Cross began testing the blood supply for evidence of HIV antibodies, an estimated 10,000 to 12,000 individuals received blood products from HIV-infected donors. Most recipients develop infection after transfusion with HIV-tainted blood products, and recent data suggest that the time to development of advanced disease is shorter among transfusion recipients than among those who acquired their disease via sexual contact.

Since 1985, the rate of HIV transmission through transfusion has dropped precipitously. The current estimated rate of transmission is 1 in 40,000 to 1 in 200,000 units of blood, depending on the prevalence of HIV infection in the community where the blood was collected. Pooled plasma components often require 2000 to 30,000 donors per lot and represent a higher potential risk of transmission than single-donor blood products if the pooled product is not treated to eliminate infectious virus.

Prevention
Aggressive efforts by the American Red Cross have greatly reduced the risk of HIV transmission via transfusion in the United States. Voluntary self-deferral of donors at risk for HIV acquisition in the community was initiated in 1983. The effectiveness of self-deferral is limited, however, by social pressures. Some high-risk individuals view blood donation as a means of being tested for HIV and provide erroneous screening information in order to receive free, confidential evaluation of their HIV status. Other at-risk individuals may be coerced to participate in blood donation drives at work. Potentially infected donors may feel uncomfortable excusing themselves from donation and provide false information on screening in order to avoid possible disclosure of a high-risk lifestyle to their coworkers. Self-deferral programs are most effective when free, voluntary testing centers are readily available elsewhere in the community and when blood drives encourage potential donors to come to donation centers by themselves and not in groups.

The institution of HIV antibody testing of donated blood and blood products in 1985 has had the most dramatic effect on lowering the incidence of transfusion-related transmission. When combined with voluntary self-deferral, the blood supply has become relatively free of HIV. Heat inactivation processes for cryoprecipitate and clotting factor concentrates have virtually eliminated transmission of HIV through use of these products. Other products, such as immune globulin preparations and hepatitis B vaccines, are produced via methods that inactivate HIV and have never been associated with transmission of HIV.