The safety and immunogenicity of the vaccines against pandemic (H1N1) 2009 influenza

The current pandemic (H1N1) 2009 influenza is spreading worldwide with a significant increase in morbidity and mortality noted in Israel, as well as in many other countries of the Northern Hemisphere. In an attempt to minimize severe morbidity and mortality, immunization projects have been initiated. This review describes the scientific data regarding safety and immunogenicity of the pandemic (H1N1) influenza vaccines which were approved for use in Israel. The approval was based on: (1) broad experience with seasonal flu vaccines; (2) data from the research and development processes of pandemic vaccines; (3) experience with adjuvants used in other vaccines and (4) post-marketing data. The immunogenicity of the approved vaccines is excellent: at least 92% develop protective antibody titers following a single vaccine dose. The vaccines are considered safe and severe side effects are very rare. Mild and transient adverse effects are similar to those following seasonal flu vaccines: local side effects in up to 12-18% and systemic adverse effects in up to 8%. The safety of the adjuvants and thiomersal is described in this review. The vaccines currently used in Israel were approved by the European Medicines Agency (EMEA) after the agency was satisfied with available safety data. Finally, the current pandemic 2009 (H1N1) influenza immunization program in Israel is described.