Has Hepatitis A Virus Been Transmitted by Clotting Factor Concentrates among Hemophiliacs in the United States?

Hepatitis A virus (HAV) infection occurred after administration of factor VIII concentrate in Europe associated with one manufacturing process. We determined if there was an excess prevalence of anti-HAV among hemophiliacs in the United States, and whether any infections here were potentially concentrate-associated. We observed clotting disorder patients and household members for up to 7 years at 6-month intervals. Selected specimens were titered for anti-HAV-immunoglobulin G content to distinguish whether they were passively or actively acquired. Our results show that anti-HAV prevalence was 20–25%, but males with clotting deficiencies had a 44% rate (p < 0.001). Passive anti-HAV (≥ 30 to < 950 mIU/ml) from intermediate-purity factor VIII may have protected against community HAV exposure. Factor IX concentrates, which contain no anti-HAV, did not protect and a few instances of past transmission are possible. Criteria for present-day concentrate-associated cases were developed; no subject conclusively met these criteria during the period between late 1985 and May 1993. In conclusion, the excess of anti-HAV prevalence in male clotting disorders is attributable to both passive administration in concentrate, and past therapy prior to concentrates. No untoward HAV event related to concentrate was found in our population, but measures to prevent transmission of nonenveloped viruses should be instituted.