# 3524
As long ago as the 1st of May (see Maryn Mckenna’s article for CIDRAP Path to swine flu vaccine has major hurdles) we started hearing rumors that the novel H1N1 seed viruses, used to grow vaccine antigen in eggs, were not growing as well as normal seasonal flu strains.
With a world scrambling for as many doses of pandemic vaccine for this coming fall and winter, any drop in the production rate is a serious concern.
Over the past couple of weeks we’ve gotten confirmation of those early rumors, which Helen Branswell wrote about on July 12th (see Branswell: Swine Flu Vaccine Yield Less Than Optimal).
At last report, there were attempts underway to create new – hopefully better producing – seed strains. But tonight we learn that hopes for a better producing strain may be dimming.
Helen Branswell, ace medical reporter from the Canadian Press, brings us the details. Follow the link to read her story in its entirety.
Efforts to improve swine flu vaccine yields drawing a blank, experts warn
By Helen Branswell, Medical Reporter, The Canadian Press
TORONTO - It may take substantially longer to make the full amounts of swine flu vaccine countries have contracted to buy because efforts to improve the yield of the vaccine seed strains aren't bearing fruit, experts say.
Three of the laboratories involved in the work are sounding increasingly pessimistic that the yield problem can be fixed in the short term. Vaccine manufacturers have reported they are getting between 50 per cent and 75 per cent less vaccine with the new H1N1 virus as they do when they make seasonal flu vaccine.
"It's not looking very bright at the moment," John Wood, principal scientist at Britain's National Institute for Biological Standards and Control, said in an interview Tuesday.
"In effect, it means if we continue like this, manufacturers will have to keep on producing (pandemic) vaccine for longer to make the number of doses needed."
The flu laboratories at the U.S. Centers for Disease Control have made three new seed strains and are in the process of completing the paperwork needed to ship them to the manufacturers.
The head of the CDC's influenza division said while the new vaccine candidate viruses are growing well in the hands of her scientists, there's no guarantee they will produce a better yield when manufacturers start to work with them.
Dr. Nancy Cox said the issue isn't simply about growth, but also about how well the vaccine viruses hold up during the various steps of the manufacturing process.
"I think it is possible we won't have a better yielding virus," she admitted from Atlanta.
"(But) I think that it's still too early to say how this will impact the amount of vaccine that's available."
While increases in the vaccine yield are still possible, right now it is looking like the amount of vaccine that is likely to be ready this fall will be less than was originally hoped for.
The road to a vaccine is often a bumpy one, and one should always take the `best-case production scenarios’ issued by organizations like the WHO with a large grain of salt.
There is probably no better overview of the problems inherent in the creation, production, and distribution of a vaccine than Maryn McKenna’s award winning 7-part series the Pandemic Vaccine Puzzle which she wrote for CIDRAP in 2007.
Part 1: Flu research: a legacy of neglect
Part 2: Vaccine production capacity falls far short
Part 3: H5N1 poses major immunologic challenges
Part 4: The promise and problems of adjuvants
Part 5: What role for prepandemic vaccination?
Part 6: Looking to novel vaccine technologies
Part 7: Time for a vaccine 'Manhattan Project'?
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