WHO informal consultation on characterization and quality aspect of vaccines based on live viral vectors, December 2003
Beyond conventional vaccines which include live attenuated, inactivated, toxoid, subunit and conjugated vaccines much progress has been made towards the development of novel vaccines and vaccination approaches. It is recognized that effective in vivo antigen production, achieved by using modified live viruses as vectors to deliver antigen(s) or antigen-encoding gene(s) to vaccination sites, is a promising approach for future immunization. For example, much relevant scientific and clinical data concerning the design, manufacture, non-clinical testing, and safety of recombinant vaccinia virus vaccines has accumulated over the past 20 years. Such data indicate the potential “strengths and weaknesses” of viral vaccines that express heterologous antigens. Live viruses considered for development encompass attenuated, replication restricted, and replication defective vaccine candidates. The WHO has recognized that novel technologies involved in the development and manufacture of live viral vectors will generate new quality, efficacy and safety issues. To review experiences with the development and evaluation of vaccines based on live viral vectors and to discuss related regulatory issues, a Consultation, jointly organized by the WHO “Initiative for Vaccine Research” and the “Quality Assurance and Safety of Biologicals” team, was held in Geneva, 4-5 December 2003. The Consultation was attended by representatives from National Regulatory Authorities (NRAs), the vaccine industry and academia (list of participants in annex 1) and chaired by Dr Klaus Cichutek (Paul Ehrlich Institute, Germany); Dr Anthony Meager (NIBSC, UK) served as rapporteur.