Abstract
The spread and evolution of highly pathogenic influenza A/H5N1 viruses in birds worldwide, and the associated human fatalities, have raised concern about an imminent influenza pandemic. Studies evaluating the safety and immunogenicity of traditional (egg-grown, subvirion and whole virus) vaccines and alternative vaccine approaches (recombinant, live-attenuated and adjuvanted vaccines) have been performed. Results show that, using unadjuvanted subvirion vaccines, at least two vaccine doses containing high dosages of influenza virus hemagglutinin are needed to elicit a titer of antibody that has been associated with protection in vaccinated subjects. High antigen-dosage requirements may be reduced and immunogenicity improved with the use of whole virus vaccines or adjuvants, such as MF59 and GlaxoSmithKline proprietary adjuvant. There is a suggestion that prepandemic priming against drifted H5N1 variants is possible; however, additional data are needed. Newer approaches using live-attenuated, DNA vaccines and conserved epitopes are currently under development.
Acknowledgements
NIH/NIAID contract N01-AI-25465. The contract’s principal investigator is Wendy Keitel.
Financial & competing interests disclosure
El Sahly and Keitel have received research support from Protein Sciences Corporation. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.
No writing assistance was utilized in the production of this manuscript.