Human blood is the source of a wide range of medicinal products used for the prevention and treatment of a variety of often life-threatening injuries and diseases. Despite measures such as donor selection, testing of donations and of plasma pools, the transmission of blood-borne viruses by plasma and purified plasma products is still considered to constitute a risk to patients. Over the past 15–20 years, the transmission of the principal viral threats historically associated with these products — hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) — has been greatly reduced or eliminated in many areas of the world. This is a consequence of the more sensitive methods being used to screen donated blood and plasma pools, and of the establishment of manufacturing practices that lead to significant virus inactivation and removal. Several procedures for virus inactivation and removal have proven to be robust and to contribute substantially to blood product safety. Viral inactivation methods should be applied to all blood plasma-derived protein solutions.
Continuing concerns about the quality and safety of plasma-derived medicinal products have resulted in a number of urgent requests from Member States for support and advice from WHO. Moreover, the World Health Assembly Resolution No 50.20, of 13 May 1997 on the "Quality of biological products moving in international commerce", requested WHO to extend the assistance offered to Member States to develop and
to strengthen their national regulatory authorities and control laboratories to increase competence in the area, and to extend efforts to upgrade the quality and safety of all biological products worldwide.
The present WHO Guidelines on viral inactivation and removal procedures intended to assure the viral safety of human blood plasma products were developed to complement the WHO Requirements for the "collection, processing and quality control of blood, blood components and plasma derivatives"(1), in response to the above requests. These Guidelines pertain to the validation and assessment of the steps for viral inactivation and removal employed in the manufacture of human blood plasma derivatives and virally inactivated plasma for transfusion, prepared either from plasma pools or from individual donations.. It is hoped that this document, by summarizing current experience with well recognized methods, will help set expectations, serve as a guide to speed implementation, and ensure that implementation is appropriate.
Inevitably, individual countries may formulate different policies, not only in relation to procedures for validation and control, but also regarding donor selection and methods of blood screening. These Guidelines do not replace the requirements of regulatory authorities in various parts of the world (2–4); rather, they are primarily intended to assist those national regulatory authorities and manufacturers that are less familiar with viral decontamination processes. The document does not address products of animal origin or those manufactured by recombinant techniques.