Posted: Sun Jul 19, 2009 10:29 am Post subject: Baxter & Novartis Report Poor Vax Harvest From Eggs
Lab workers are harvesting one dose or less of the component they need from each egg in which the virus is grown, said Eric Althoff, a spokesman for the Swiss drugmaker. That's between 1/3 and 1/2 of the typical yield for a seasonal flu vaccine, he said.
Most manufacturers make flu vaccines by injecting chicken eggs with an approved version of the virus to provide it with nutrients to grow and multiply. The amount of virus that grows in the egg and can be turned into shots is called its yield. One egg will usually produce enough antigen to make two doses of seasonal flu vaccine, according to Oswald.
It is well known that some strains are good yielders, and some strains are bad yielders, Marie-Paule Kieny said in a teleconference on July 13.
"Unfortunately we didn't come up with a good yielder in the first series of strains," she said. "To remedy that, the WHO laboratory network is again trying to generate new vaccine viruses from patients who have been infected. We hope that one of them will be giving higher yields, comparable to the ones obtained with seasonal vaccines."
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