I still haven't been able to determine what magical means will be used to produce a vaccine against the H5N1 strain of Avian Flu.  Press is very thin on how production and testing of the vaccine is going.  Yet policy decisions are being made based on the notion that the vaccine will be available in quantity soon.

A press release on the CIDRAP site from the World Health Organization notes that WHO will probably recommend governments start stockpiling vaccines against H5N1.  The release also cites unnamed "U.S. officials" who say that clinical trials of vaccines from Chiron and Sanofi-Pasteur are supposed to start soon, while also noting that, "H5N1 may not match the pandemic strain, the vaccine's shelf life of up to 2 years is relatively short, and, because companies have not yet begun clinical trials, licensing of the vaccine is months away."

And in another release, the CIDRAP site quotes Michael Osterholm, who is director of the University of Minnesota Center for Infectious Disease Research and Policy, "We don't have a pandemic strain of vaccine yet, and we don't have any idea whether any of the vaccines to date would be efficacious."  In the Technological Challenges to Vaccine Development section of the Pandemic Influenza overview at CIDRAP, we find; "Highly pathogenic avian strains cannot be grown in large quantities in eggs because they are lethal to chick embryos."

To the extent that we should trust the popular press on this issue, as part of a short story on What You Need to Know About Avian Flu, the 9 February, 2004 issue of Business Week states, "Vaccines are usually produced in chicken eggs, but H5N1 is lethal to fertilized eggs."

Yet a 24 February, 2005 story on Newsday.com says, "Two million doses of vaccine are being stored in bulk form for possible emergency use and to test whether it maintains its potency," while 8000 doses are, "nearly ready to be shipped to the National Institute for Allergy and Infectious Diseases for clinical trials."

Perhaps the vaccine about to enter trials is from source other than chicken eggs?

In 10 February, 2005 testimony before the The Committee on Government Reform, Jesse L. Goodman, Director of the Center for Biologics Evaluation and Research at the FDA, while describing how the Department of Health and Human Services will spend roughly a billion dollars over the next few years on influenza related activities, said; "While work remains to obtain sufficient vaccine yields and evaluate cell-based vaccines for their safety and effectiveness, moving from an egg-based production to a cell-culture production can potentially shorten the time needed to produce vaccine as well as decrease the risk of contamination inherent in egg-based production."  That is, there isn't yet a functional alternative to using chicken eggs to produce vaccine.

So what gives?  I can only speculate that details about the vaccine are being closely held until more is learned about how it behaves in humans.  But with so many sources suggesting the vaccine can't be grown in eggs, I have to wonder what tricks Chiron and Sanofi-Pasteur have come up with to produce it in bulk.  Perhaps it is a low yield process and they have concentrated the virus produced from a much larger number of eggs?

I wish someone would come out and clearly explain where the vaccine is coming from and how it is produced.  The issues of what infrastructure exists to make vaccines, how much can be made, and whether it will be effective are quite critical for charting our course as we prepare for a potential pandemic.