Questions still linger over a 1976 swine flu scare in which the quickly developed vaccine was believed to be linked to a rare, but serious, side effect. The vaccination effort was ended nearly as quickly as it was begun, after just 10 weeks.
One wrinkle in any plans to manufacture a swine flu vaccine is the seasonal flu vaccine. Currently, millions of doses are under production and some have worried that any new vaccine could disrupt that process. But Besser said protecting against the seasonal flu, which kills an average of 36,000 Americans each year and hundreds of thousands across the globe, remains the priority and no corners will be cut in the production of that vaccine. Only when those doses are completed will vaccine makers move on to the swine flu, he said.
The CDC and the World Health Organization are sending basic ingredients to drug companies, which will study whether they can produce a vaccine. Should health officials determine the swine flu is enough of a threat to public health that a vaccine is necessary, only then will the actual manufacturing process begin.
At Gaithersburg-based MedImmune Inc., that process is slightly altered. Because the company makes a flu vaccine from live virus that is sprayed into the nose, scientists there need to grow their own seeds. Earlier this week, live swine flu virus was delivered there, said George Kemble, the company's vice president for research and development.
"We want to be sure that we're prepared when that decision is made," he said. "We're moving forward assuming they're going to ask us to go forward and make that vaccine."
Chicago-based Baxter International Inc. expects to receive samples of the virus strain in the next couple of days, said Christopher Bona, a Baxter spokesman. But the process from "seed strain" to vaccine is long and complex, and the company would not speculate on when a vaccine might be available to the public.
First, the virus sample will be evaluated and tested, a process that could take three to four weeks. Baxter's process is unlike that of traditional seasonal flu vaccine makers, which grow millions of copies of the flu virus in chicken eggs. Instead, Baxter grows the virus in a line of cells. It's then separated, filtered, tested and packaged - a total process that is faster than the traditional development involving eggs, Bona said.
Baxter would be able to make the vaccine available to the public 12 to 16 weeks after the start of manufacturing it, Bona said.
Drugmaker GlaxoSmithKline PLC is also expecting a sample of the virus. The London-based company's process from sample to vaccine that is ready for the public could take four to six months, but it's unclear when that process would begin, spokesman Jeff McLaughlin said. The company is in contact with officials from the CDC and the WHO for guidance on next steps, he said.
The process of making a new flu vaccine follows the same steps as for former flu strains. There are many viruses that there is no vaccine for. But since manufacturers already have so much experience with the flu, they are better able to adapt to a new strain.
"This is one of the simpler ones," said Christine Layton, a Baltimore-based public health scientist who has studied flu vaccine for the U.S. Department of Health and Human Services. "We know how to make a flu vaccine that is reasonably effective and reasonably safe."
The Associated Press contributed to this article.
