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Swine Flu Vaccine May Take Longer

Add 2 months to the timetable for producing a vaccine against the virus causing the swine flu outbreak, says an advisory group to the World Health Organization (WHO).

It may be mid-July before manufacturers have the appropriate “seed stock” to start making the vaccine against the new A (H1N1), according to a report posted online today from a WHO working group on vaccines that met via teleconference on 14 May. The report says a crude form of the seed stock likely will be ready by the end of the month, but 1 to 2 weeks of testing in animals will be required. Manufacturers typically need 1 to 2 months more to find the fastest growing strains that will produce the most surface proteins from the virus, which are the main ingredients in a vaccine. The group warned that moving too quickly “could result in starting vaccine production with strains of lower growth potential,” as happened with a strain of H5N1, the bird flu virus. “Using a poorly growing A (H1N1) virus could reduce global supplies of A (H1N1) vaccine,” the group warned.

On 1 May, Marie-Paule Kieny, director of WHO’s initiative for vaccine research, predicted that the seed stock would be ready “by mid- or end of May.” Kieny, who spoke at a press conference, said, “The reality is that from the time the potentially pandemic virus is identified, it takes between 4 to 6 months to have the first doses of vaccine coming out of the factory and be available for immunizing people.”

The working group report does not address when a final product likely will exist but estimated that 4.9 billion doses “could be produced over a 12-month period after the initiation of full-scale production.” The group noted that this would require using “the most dose-sparing formulations,” which means adding vaccine boosters called adjuvants; approved flu vaccines in some countries, including the United States, do not use adjuvants. But four European countries recently guaranteed GlaxoSmithKline that they would purchase more than 100 million doses of a vaccine that it plans to make against the novel H1N1 strain with an adjuvant.

The working group “considered it premature” to start commercial-scale production of the vaccine and also stressed that even if WHO bumps up the outbreak from a phase 5 alert to phase 6, indicating a full-scale pandemic, that “does not automatically mean that WHO is recommending that manufacturers should switch from seasonal to influenza A (H1N1) production.”