posted by admin on 20/02/07
A vaccine for avian influenza is at hand. Now regulators and companies are weighing whether to make it widely available before any outbreak occurs.
To date, the H5N1 virus that causes the flu has passed only occasionally from birds to humans. The possibility of a mutation of the virus causing a large-scale, highly lethal outbreak among humans motivated big pharmaceutical companies such as GlaxoSmithKline PLC and Sanofi-Aventis SA to develop vaccines. The Food and Drug Administration hasn't approved any of them yet; indeed, the vaccine has yet to get an endorsement from any regulatory agency for use before a pandemic, but some governments already are stockpiling supplies.
The existence of a bird-flu vaccine raises a number of questions. Will it be effective against a mutation of H5N1? If so, should it be administered only after a pandemic is indicated?
The unknowns haven't deterred pharmaceutical companies who saw the potential demand for a vaccine last year, when fears of a bird-flu pandemic sent people around the world rushing to buy up supplies of Roche Holding AG's antiviral drug Tamiflu to treat the disease. An effective vaccine could be just as important as Tamiflu, if not more important, in saving a person from avian influenza.
Sanofi has been besieged by requests for its vaccine. "We have calls from people saying, 'Can I buy it? Can I buy it?' " says Alain Bernal, a spokesman for Sanofi Pasteur, the vaccine unit of Sanofi-Aventis of France.
Given that the threat of a pandemic is hypothetical at this stage, experts say it wouldn't make sense to cut corners on a normal regulatory process. They also point out that production capacity is needed to make vaccines for seasonal influenza, which poses a more immediate threat.
At Sanofi, Mr. Bernal says making bird-flu vaccine for a potential threat would cut into the company's production capacity for vaccines for seasonal flu, which kills about 36,000 people annually in the U.S. alone. By contrast, the H5N1 strain of bird flu, the one that worries health authorities most, has infected at least 273 people world-wide, killing 166 of them, mostly in Asia, since the virus re-emerged in late 2003, according to the WHO.
Mr. Bernal says global vaccine-production capacity for seasonal influenza already is limited to an estimated 350 million doses a year, of which Sanofi Pasteur produces about half. "The real public-health need today is for seasonal flu," he says. "You either produce [vaccines for] seasonal flu or H5N1." As a result, the H5N1 vaccine "is not a vaccine that we want to sell to the public," Mr. Bernal says. "We don't have a marketing strategy for this product." A committee of outside advisers to the FDA is scheduled to meet Feb. 27 to make recommendations on the safety and effectiveness of Sanofi's H5N1 vaccine.
In addition, the current H5N1 vaccines seem to require a high dose to offer protection, making production issues worse, says Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, which has been working with vaccine makers on an antidote for a government stockpile. "It's not going to be something you're going to see on the shelf for sure," Dr. Fauci says. "It will likely be strictly controlled."
The current vaccines are based on strains of the H5N1 bird-flu virus from recent years; should the virus mutate, as it would need to do to spread among humans, it isn't clear that it would fully protect people.
Still, some experts think the current vaccine probably would protect against severe illness and death, even if the victim still got sick. Governments are proceeding on that assumption, and millions of doses have been produced.
The U.S. has purchased from Sanofi enough vaccine for at least three million to four million people, according to Dr. Fauci. The U.S. government is currently negotiating to purchase more vaccine, he says, with the ultimate goal of securing enough to protect 20 million people. Still, Dr. Fauci adds, the U.S. isn't considering vaccinating people pre-emptively with the product currently available.
GlaxoSmithKline received approval from European drug regulators in December for one of its H5N1 vaccines, but only for use in the event of a pandemic, according to Alice Hunt, a spokeswoman in London for the company. Last month, the British drug company submitted another application for an H5N1 vaccine that could be used in advance of a pandemic.
Jean-Pierre Garnier, Glaxo's chief executive, said recently that the vaccine could prove effective against mutations of H5N1. He also said Switzerland has bought one vaccine dose per capita.
CSL Ltd., an Australian pharmaceutical company, announced last month that it had produced a safe, effective vaccine against H5N1. Australia's drug watchdog will soon review the company's application. CSL has no plans to market a version of the vaccine for general use, according to Rachel David, the company's spokeswoman.
Medical-products maker Baxter International Inc., of Deerfield, Ill., is testing its H5N1 vaccine and has signed a deal with the British government to produce two million doses for a stockpile. The company hasn't yet submitted it for approval to the FDA in the U.S.
Whether Baxter will ever market the vaccine directly to consumers is an open question, according to Deborah Spak, a spokeswoman for the company.
"We are still under clinical evaluation and years away from receiving the approvals needed for commercialization," Ms. Spak says, adding that the company hasn't built sales of a bird-flu vaccine to consumers into any of its financial projections.
Some companies do say they see commercial potential in the vaccine. In November, the Swiss drug giant Novartis AG submitted its H5N1 vaccine to the European Medicines Agency in London for approval, according to Eric Althoff, a spokesman for the vaccine unit of the Swiss company. Mr. Althoff says he expects a response on that application this year.
Mr. Althoff says further that if that response is positive, Novartis believes there is a potential commercial market for a vaccine that would be sold to individuals and not just governments to ward off a pandemic.
Write to Nicholas Zamiska at firstname.lastname@example.org