Vaccine makers are slow to perfect new techniques
Tuesday, November 24, 2009
After a lethal bird flu virus emerged in Asia, U.S. officials launched an intense effort to build new defenses against a pandemic, including replacing an antiquated vaccine system, which depends on millions of chicken eggs.
But six years later, as Americans from Washington to California line up to get inoculated against the swine flu, the slow progress toward developing better ways to make a vaccine has become glaringly obvious.
This lag and the shortage of H1N1 vaccine have focused attention on the status of government efforts to develop state-of-the-art techniques to make flu and other vaccines, including those needed to protect against bioterrorism, and the nation's dependence on a process that is notoriously slow and unreliable.
Several new technologies are showing promise. Spurred by $487 million in federal funding, a sprawling new vaccine factory is opening in North Carolina Tuesday that will produce shots using dog cells instead of chicken eggs. A Connecticut biotech company has also applied to sell a vaccine employing a radically different approach involving a genetically engineered virus infecting insect cells -- a strategy a Rockville firm is testing to inoculate people against the swine flu in Mexico. Dozens of other high-tech approaches are also moving through the pipeline.
While several companies are trying to ready their new techniques in case the H1N1 pandemic worsens, most of these remain years away from contributing significantly to the world's capacity to respond to a deadly new pathogen.
"If this pandemic had come next year, we might have had some of these vaccines licensed and we would have been able to use them -- our investments might have borne fruit," said Robin Robinson, who directs the Health and Human Services Department's Biomedical Advanced Research and Development Authority (BARDA). "But unfortunately they didn't help us this year. Others still have a ways to go."
The most immediate solution to the vaccine shortage would be adjuvants -- compounds that boost the immune response, allowing limited stock to be stretched into more doses. H1N1 vaccine with adjuvants is available in Europe, Asia, the Middle East, Canada and Mexico. The United States has decided against using adjuvants because the Food and Drug Administration has not fully reviewed them. Officials worried that a new product would make people even more nervous about the inoculation.
For decades, flu vaccine has been produced by identifying which strains of flu virus were most likely to be circulating, tinkering with microbes in the laboratory to create "seed" virus, injecting that virus through the fragile shells of newly fertilized chicken eggs and waiting several days for the microbes to grow.
The process takes six to nine months and is highly unpredictable. The H1N1 seed virus initially grew inside the eggs at only about a third to a quarter of the expected rate, accounting for most of the lag in production.
"All kinds of things can go wrong," said Anthony S. Fauci of the National Institute of Allergy and Infectious Diseases. "It's a time-honored but nonetheless fragile technology."
In addition, the process relies on having access to millions of eggs -- each egg typically produces one to three doses of vaccine. If the next pandemic is caused by a virus that kills birds, like the H5N1 avian flu virus that emerged in 1997 in Hong Kong and reemerged in 2003, any process dependent on chickens would be vulnerable.