Swine flu vaccine production has hit a snag, with manufacturers reporting a disappointingly low yield when vaccines viruses are grown in eggs.
The World Health Organization says so far the yield for egg-based production is half or less what manufacturers get when they make vaccine to protect against seasonal H1N1 viruses. The lion’s share of influenza vaccine is made by companies that grow the viruses in eggs.
New seed strains are being made in the hopes of increasing the vaccine yield, a report by the WHO’s vaccine chief, Dr. Marie-Paule Kieny says.
But if the yield cannot be increased, it will slow the rate at which pandemic vaccine comes out of the production pipeline, adding to the time it takes to protect populations in countries like Canada that have purchased vaccine.
And countries that haven’t pre-ordered pandemic vaccine would face substantial delays before manufacturers have product to sell to them.
“There’s nothing to suggest it will take longer to make vaccine, if in fact everything goes as planned. The question is: How much?” says Dr. Michael Osterholm, director of the Centre for Infectious Diseases Research and Policy at the University of Minnesota.
Somewhere between 850-900 million and 1.8 billion doses of pandemic vaccine are already spoken for, she reports.
The low end of the scale represents what would be needed by countries with contracts if it is shown that one shot will be enough to protect a person; the high end represents what those countries would need if two shots per person are required.