Blood protein derivative viral safety: observations and analysis

The well-documented viral safety of albumin arises from several factors operating in concert, including virus removal during preparation, immune neutralization, serendipitous inactivation, virus sterilization through pasteurization. Safety with respect to HBV transmission was achieved even prior to the development of sensitive screening tests for HBsAg, as can be predicted given the initial virus load and the influence of factors affecting removal and inactivation. Coagulation factor concentrates, as traditionally prepared, are known to have transmitted the viral agents of hepatitis and AIDS with high frequency. Application of virucidal procedures to these concentrates, in some cases, appears to have eliminated virus transmission, raising the question as to whether absolute safety has now been achieved. Clinical proof of absolute safety is made difficult by the small number of eligible patients who can be monitored, lengthy and expensive monitoring procedures, and opportunity for transmission of virus by product-independent routes. Based on viral load analysis, modern coagulation factor concentrates are predicted to have the same probability of freedom from HIV, HBV, and HCV transmission as that exhibited by albumin.