Vaccines to protect people against a highly virulent H5N1 bird flu pandemic are made using the embryos of hens’ eggs. “Although it is the best we have, for the long term it’s probably not” explained Peter Wright, a professor of pediatrics at Dartmouth College in Hanover, New Hampshire.Not enough doses
Wright says because chickens lay most of the eggs in the spring the vaccine production method, which was developed a half century ago, limits how many doses can be produced.
The eggs are used to grow the virus to make the vaccine that prompts the immune system to target the disease. Writing in the New England Journal of Medicine, Wright says an experimental vaccine that’s produced using monkey cells begins to address some of the problems with the current stockpiles of avian flu vaccine. Using primate cells
Hartmut Ehrlich, who is with Baxter Bioscience in Vienna, Austria and is the study’s lead author, says using primate cells to make the vaccine could significantly reduce the amount of time it takes to manufacture the vaccine. “That means from the time we and other manufacturers are getting the pandemic strain for producing the vaccine it will take us about 12 weeks less,” he noted. “So that translates into three months to have vaccine ready to ship out.”
In a clinical study involving 275 individuals, the two-dose vaccine protected p to 76 percent of the participants after 21 days. Ehrlich says other experimental H5N1 vaccines are not as protective. Meanwhile, global health officials remain concerned that millions of doses of avian flu vaccine that have been stockpiled for years in anticipation of a bird flu pandemic are beginning to lose their potency. Officials are calling for adjuvants, or additives, to be set aside to strengthen the vaccines.Subscribe here to the free poultry newsletter