Seasonal influenza continues to have a huge annual impact in the United States, accounting for tens of millions of illnesses, hundreds of thousands of excess hospitalizations, and tens of thousands of excess deaths. Vaccination remains the mainstay for the prevention of influenza. In the United States, 2 types of influenza vaccine are currently licensed: trivalent inactivated influenza vaccine and live attenuated influenza vaccine. Both are safe and effective in the populations for which they are approved for use. Children, adults <65 years of age, and the elderly all receive substantial health benefits from vaccination. In addition, vaccination appears to be cost-effective, if not cost saving, across the age spectrum. Despite long-standing recommendations for the routine vaccination of persons hi high-priority groups, US vaccination rates remain too low across all age groups. Important issues to be addressed include improving vaccine delivery to current and expanded target groups, ensuring timely availability of adequate vaccine supply, and development of even more effective vaccines. Development of a vaccine against potentially pandemic strains is an essential part of the strategy to control and prevent a pandemic outbreak. The use of existing technologies for influenza vaccine production would be the most straightforward approach, because these technologies are commercially available and licensing would be relatively simple. Approaches currently being tested include subvirion inactivated vaccines and cold-adapted, live attenuated vaccines. Preliminary results have suggested that, for some pandemic antigens, particularly H5, subvirion inactivated vaccines are poorly immunogenic, for reasons that are not clear. Data from evaluation of live pandemic vaccines are pending. Second-generation approaches designed to provide improved immune responses at lower doses have focused on adjuvants such as alum and MF59, which are currently licensed for influenza or other vaccines. Additional experimental approaches are required to achieve the ultimate goal for seasonal and pandemic influenza prevention-namely, the ability to generate broadly cross-reactive and durable protection in humans.
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Potential conflicts of interest: K.L.N. has received research funding and served on advisory boards for influenza vaccine manufacturers GlaxoSmithKline and MedImmune. J.J.T. has research funding from Protein Sciences Corporation, ID Biomedical, and Merck.
The “Seasonal and Pandemic Influenza 2006: At the Crossroads, a Global Opportunity” conference was sponsored by the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the National Institute of Allergy and Infectious Diseases, and the Centers for Disease Control and Prevention. Funding for the conference was supplied through an unrestricted educational grant from Gilead Sciences, Glaxo-SmithKline, Roche Laboratories, MedImmune, Sanofi Pasteur, Biota Holdings, and BioCryst Pharmaceuticals.
Supplement sponsorship. This article was published as part of a supplement entitled “Seasonal and Pandemic Influenza: At the Crossroads, a Global Opportunity,” sponsored by the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the National Institute of Allergy and Infectious Diseases, and the Centers for Disease Control and Prevention.