updated 11/15/2005 8:12:01 PM ET 2005-11-16T01:12:01

Companies are proposing a change in how they make flu vaccine that they believe will improve the nation’s ability to fight the viruses and modernize the process.

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Basing production on cell cultures in a laboratory rather than chicken eggs, the traditional source of flu vaccine for a half-century, could make the vaccine more expensive. The Food and Drug Administration has raised concerns that other viruses or cancer cells could make their way from the cell cultures to the vaccine and, ultimately, into people.

Any approval for changes is some time away, but expert agency advisers are meeting in the Washington suburbs on Wednesday to discuss the potential benefits and risks of the proposals.

Representatives from Chiron Corp. and Solvay Pharmaceuticals, which are developing a flu vaccine using a cell line taken from the kidney of a dog decades ago, will address the FDA’s advisory committee that oversees proposed vaccines.

In briefing documents, FDA scientists say that using the dog kidney cells “could yield significant benefits” and suggest any risks could be limited by careful testing of the cells and the vaccine production process.

“These cells offer significant advantages for routine influenza vaccine manufacturing, as well as being able to meet the unique challenges of pandemic vaccine manufacturing posed by virulent avian strain candidates,” the agency said.

Currently, one dose of flu vaccine, for either the annual regular flu shot as well as bird flu, is grown inside a single egg, a method that has been in use since the 1940s. Immunizing the U.S. for a flu season usually involves the processing of 80 million chicken eggs or more — a logistically complex task.

Manufacturing flexibility
Those eggs must be ordered six months in advance, forcing companies to anticipate the demand for vaccine well before the start of the flu season. A cell-based system would allow manufacturers to change the composition or production rate of the vaccine within weeks, said Bruce Scharschmidt, vice president for corporate scientific affairs for Chiron.

“The major advantage is in manufacturing flexibility,” Scharschmidt said. That is a significant benefit if there is an outbreak of an unexpected strain of flu.

And because the egg supply depends on chickens, production efforts could be threatened by the spreading bird flu and the culling methods being employed to contain it overseas out of concern it will begin spreading through humans, said Harold Shlevin, president of Solvay.

Cell cultures, meanwhile, are handled in a much more controlled environment, reducing the chance of processing errors, proponents say. Last year’s flu vaccine shortage took place when Chiron Corp. was unable to release any vaccine for the U.S. market because of possible contamination at its production plant.

People who are allergic to eggs could also begin receiving flu shots if they were developed from cell cultures.

Companies including Chiron have also looked into using monkey cells to make flu vaccine. Some have already been used to produce a polio vaccine.

The price of the vaccine would likely go up with the technology involved in the new growth process, said Dr. William Schaffner, a professor of infectious diseases in the Vanderbilt University School of Medicine. The companies developing it, however, don’t want to price themselves out of the market and will take steps to control costs, he predicted.

“I’d be happy to take this vaccine and give it to everybody in my family,” Schaffner said. “Five to six years from now, we’ll be almost completely in cell-based influenza vaccine production.”

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