Hepatitis A virus and blood products: virus validation studies.

As there have been reports of the transmission of hepatitis A virus by single units of blood, virus validation studies were carried out to determine the fate of the virus at four major steps (cryoprecipitation, solvent/detergent inactivation, DEAE chromatography and lyophilization) involved in the production of solvent-detergent inactivated factor VIII products. If the reduction in infectivity is additive over the four steps, the total reduction would be between 8.6 and 9.3 log10. It is unlikely that such a reduction would provide a sufficient safety margin, particularly if the original plasma pool from which the FVIII was prepared, was obtained from a population in which hepatitis A virus was not rare. In such a situation, an additional method of effectively reducing hepatitis A virus infectivity should preferably be included in the production process.