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Officials mull using poultry vaccine on people

Canadian Press

TORONTO -- Is what's good for the goose good for Mr. and Mrs. Gander? Public health authorities exploring the possibility of protecting people against an influenza pandemic with vaccine produced for poultry say "Maybe."

The World Health Organization and others are studying whether it would be possible to tap into the global agricultural vaccine production capacity to help bridge the enormous gap between the amount of human flu vaccine the world can produce and how much would be needed in a severe pandemic.

While the idea of giving people vaccine produced for poultry may seem, well, for the birds, the proposal - advanced by eager agricultural vaccine-makers - hasn't been dismissed out of hand.

"I think it's something that does merit consideration," says Dr. Jesse Goodman, director of the U.S. Food and Drug Administration's Center for Biologics Evaluation and Review. (Vaccines are considered biological products.)

Goodman and others would rather not have to resort to this option, hoping a pandemic is far enough off and new investment in novel production methods and facilities is sufficient to vastly expand output within the human influenza vaccine sector.

But given the current limited vaccine capacity, all sorts of options would have to be on the table if a harsh pandemic were to strike soon. And harnessing agriculture vaccine production is one of them, Goodman says.

"I would say our goal would be to keep an open mind about possible approaches in an emergency," he said in an interview from Washington.

"For a medium-to long-term approach, certainly enhancing the capacity and use of the human vaccines in my mind would be the first priority. . . . (But) in the short-term emergency point of view . . . I think it is wise to look at all possible approaches and alternatives."

Canada is unlikely to need to explore this option. The country has a long-term contract for pandemic vaccine to be made at a production facility located in Ste-Foy, Que.

But most other countries, including the United States, currently don't have enough domestic production capacity to be able to vaccinate their citizens during a flu pandemic - hence the outside-the-box exploration of options.

Experts say the agricultural vaccine sector's greatest potential for humans lies as a possible source of antigen (vaccine-ready virus) for live attenuated vaccines such as FluMist, the inhaled vaccine produced by MedImmune Inc., headquartered in Gaithersburg, Md.

That's because antigen used in live attenuated vaccines is not put through the investment-intensive purification and sterilization processes used in the manufacture of inactivated (killed virus) vaccine, the type contained in flu shots.

The production processes for live attenuated vaccine and agricultural vaccine are quite similar, says Dr. Klaus Stohr, the WHO's special adviser on influenza pandemic vaccine development. So are the criteria - known as good manufacturing practices - set down for production of agricultural and human flu vaccines.

"So theoretically - theoretically - it's conceivable that this antigen, and there's a lot of antigen produced by the agricultural vaccine makers, could with much less investment be transformed into live attenuated vaccines," Stohr says.

A MedImmune executive says the company doesn't yet know what to make of the idea, raised at a recent meeting in Geneva hosted by the WHO.

"We're just beginning to discuss this in MedImmune and we really haven't looked into it to be able to understand what that would mean," says Kathleen Coelingh, senior director of scientific affairs.

"We're not ruling anything in or anything out."

Goodman says companies which make inactivated flu vaccine might also be able increase their output by processing some antigen produced by agricultural vaccine makers.

But Stohr says human flu vaccine makers carefully match their antigen production to their capacity to purify, sterilize, bottle and label, suggesting these essential downstream steps create a bottleneck around which there is no easy or inexpensive route.

Dr. David Fedson, a retired vaccine industry executive, says there are hitches that may limit the ability to use antigen from agricultural sources to vastly increase the output of live attenuated vaccine as well.

FluMist, for instance, currently must be kept in a freezer until it is administered - a factor that might limit its usefulness in some parts of the world. As well, individual doses come pre-packaged in an inhaler, raising questions about whether adequate numbers of additional inhalers could be made and whether MedImmune or another company could expand capacity to package mass numbers of extra doses.

Modifying the delivery mechanism so that the vaccine is given in the form of nose drops could get around that potential bottleneck, Fedson says. (The Russians have been using live attenuated vaccine delivered this way for at least two decades.) But changing the vaccine would require regulatory approval.

Still, Stohr insists that with few options for rapidly and affordably increasing human flu vaccine production capacity, the notion of exploiting agricultural antigen sources is worth further study.

"There are so many things which we have seen may not work out quickly or will cost too much," he says.

"But here we have an option which has not been fully explored which has a good chance or which has a greater chance of success. And if it succeeds, it would make a profound contribution to the efforts to fill the pandemic vaccine gap."