Avian Flu Diary: CIDRAP: Part VI Of The Pandemic Vaccine Puzzle

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Maryn McKenna continues with her excellent series on the promise and problems of pandemic vaccines.

THE PANDEMIC VACCINE PUZZLE
Part 6: Looking to novel vaccine technologies

Maryn McKenna Contributing Writer
Editor's note: This is the sixth in a seven-part series investigating the prospects for development of vaccines to head off the threat of an influenza pandemic posed by the H5N1 avian influenza virus. The series puts promising advances in vaccine technology in perspective by illuminating the formidable barriers to producing large amounts of an effective and widely usable vaccine in a short time. Part 5 looked at the idea of vaccinating people before a pandemic with a best-guess vaccine and following up later with a vaccine matched to the emergent pandemic strain.

Nov 1, 2007 (CIDRAP News) – Frustration with the slow pace of pandemic-vaccine achievement has spurred second looks at both old and new technologies, such as using whole influenza viruses instead of fragments or growing flu viruses in cultures of mammalian cells instead of in eggs.

Such approaches may yield cross-protection against various H5N1 strains, shorten the production timeline, or increase the amount of vaccine that can be produced. As with the inactivated subvirion or split-virus vaccines, however, much of the research into new types of vaccines and forms of delivery is in its early stages, and the vaccines could be years away from marketability. Few of them pass the real-world tests specified recently by David Fedson, MD, in the Permanente Journal. Fedson, a retired vaccine-industry executive who has analyzed pandemic vaccine planning, wrote that the vaccines must be "scientifically promising," they must be "licensed or near licensure," and "the global industrial capacity to produce them must be large and already in place" (see Bibliography: Fedson 2007: New approaches).

Among older and known technologies, the lure of cross-reactive protection has spurred a second look at inactivated whole-virus and live-attenuated flu vaccines. Some whole-virus trials have returned encouraging results. But in the past, whole-virus vaccines' much higher rate of adverse reactions has kept them out of commercial use in the United States. As a result, "if whole-virus vaccines are confirmed to be more immunogenic than subvirion vaccines, this will pose challenges to manufacturers and regulators, since it will require substantial changes to existing licensed production processes," Iain Stephenson of University Hospital-Leicester and colleagues observed in Lancet Infectious Diseases (see Bibliography: Stephenson 2006: Development of vaccines against influenza H5).
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