Background: Estimates of the risk of transfusion-transmitted viral infections are essential for monitoring the safety of the blood supply. The aim of the present study was to estimate the residual risk of blood-borne viral infections in Spain.
Study design and methods: Incidence rates of seroconversion for HIV, HBV, and HCV were calculated among 673,018 persons who donated blood more than once (repeat donors), from 1997 through 1999 at 22 blood donation centers (for a total of 2,464,964 allogeneic blood donations and 1,052,752 person-years).
Results: Incidence rates per 100,000 person-years and their 95-percent CIs were as follows: for HBV, 8.36 (5.24-12.62); for HIV, 3.23 (2.24-4.52); and for HCV, 3.70 (2.63-5.07). After adjusting incidence rates for the estimated duration of the infectious window period for each virus, the residual risk per unit transfused was estimated at 1 in 513,000 for HIV, 1 in 74,000 for HBV, and 1 in 149,000 for HCV. The introduction of new screening test based on NAT would have reduced these risks by 27 to 50 percent for HIV, by 42 percent for HBV, and by 62 to 65 percent for HCV.
Conclusion: The residual risks of transmission of HIV, HBV, and HCV in Spain are similar to those reported in other countries and should be further reduced in the future.