The purpose of this document is to provide scientific guidance relating to the viral safety of biotechnological medicinal products used in clinical trials. Guidance is provided with respect to:
(i) the criteria for and the extent of viral safety evaluation studies, especially validation studies, that are required prior to and during clinical development.
(ii) the extent to which manufacturers are able to refer to in-house experience concerning virus safety evaluation.
(iii) the risk assessment which should form part of the safety evaluation.