Prospective investigation of transfusion transmitted infection in recipients of over 20 000 units of blood

OBJECTIVES: To follow up recipients of 20 000 units of blood to identify any transmissions of infections through blood transfusion. DESIGN: Follow up study of recipients of transfusion. SETTING: 22 hospitals in north London. PARTICIPANT: Adult patients who had recently been transfused. MAIN OUTCOME MEASURES: Patients had further blood samples taken at 9 months that were tested for markers of hepatitis B and C and HIV and human T cell leukaemia/lymphoma virus type I or II (HTLV) infections. Recent infections were distinguished from pre-existing infections by comparison with blood samples taken before transfusion. RESULTS: 9220 patients were recruited, and 5579 recipients of 21 923 units of blood were followed up. No transfusion transmitted infections were identified. The incidence of transfusion transmitted infections was 0 in 21 043 units (95% confidence interval for risk 0 to 1 in 5706 recipients) for hepatitis B; 0 in 21 800 units (0 to 1 in 5911 recipients) for hepatitis C; 0 in 21 923 units (0 to 1 in 5944 recipients) for HIV; and 0 in 21 902 units (0 to 1 in 5939 recipients) for human T cell leukaemia/lymphoma virus. Three patients acquired hepatitis B during or after hospital admission but not through transfusion; 176 (3%) had pre-existing hepatitis B infection. Sixteen (0.29%) patients had hepatitis C, and five (0.09%) had human T cell leukaemia/lymphoma virus. CONCLUSIONS: The current risk of transfusion transmitted infections in the United Kingdom is very small, though hospital acquired infections may arise from sources other than transfusion. A considerable proportion of patients have pre-existing infections.