Hepatitis, type B in haemophiliacs. Relation to the source of clotting factor concentrates.

36 children aged 3 to 18 years receiving substitution therapy for haemophilia during the period 1970 to 1976 were studied for infection with hepatitis B virus by assays for HBsAg, anti-HBs, and anti-HBc. Clinical hepatitis B occurred in 3 patients (8%) and serological evidence of infection was found in further 13 (36%). The occurrence of infection was associated with age but less so with the total amount of transfusion. Estimates of the risk of infection by clotting factor material of different origin indicated a figure of 1:53,000 I.U. for Danish volunteer donor preparations as well as for commercial products, the risk being apparently increased following the use of pooled blood donor material and non-Scandinavian products respectively.