Reconstruction of the hepatitis C virus epidemic in the US hemophilia population, 1940-1990.

Hepatitis C virus (HCV) is a blood-borne infection readily transmitted by transfusion. Persons with hemophilia were at very high risk of acquiring HCV, but the chronology and correlates of HCV incidence in the US hemophilia population remain unknown. The authors used multiple data sources and new statistical methods to reconstruct HCV incidence in White males with hemophilia A from 1940 through 1990. HCV incidence was approximately 1%/year until 1950 but 2-3%/year by 1955. With mild hemophilia, HCV incidence increased in the 1960s, reaching a plateau of approximately 8%/year from 1969 to 1980. With moderate and severe hemophilia, HCV incidence increased steeply to peaks of 11.7%/year in 1970 and 17.2%/year in 1968, respectively. Overall, HCV incidence declined after 1970, steeply after 1984, to nearly zero by 1990. With improving and increasing use of plasma derivatives, the size of the hemophilia population increased 86% during these 50 years. Study results imply that these life-saving treatments also carried an increasing risk of HCV, particularly before clotting factor concentrates were licensed in the 1970s. They also suggest that multiple synergistic interventions since 1970, particularly donor deferral, screening for hepatitis B and human immunodeficiency virus, and viral inactivation of clotting factor concentrates, were needed to reduce transfusion of HCV prior to its discovery.