Apr 29, 2009 07:33 PM | 6
As the World Health Organization (WHO) today acknowledged the spreading swine influenza virus by moving the pandemic threat awareness level up one notch to 5, the U.S. Centers for Disease Control (CDC) worked to get drug companies the materials they need to create a vaccine. Meanwhile, the U.S. Department of Health and Human Services (HHS) said it is unlikely that any new swine flu vaccine would be included in the batches of seasonal influenza vaccines already in production for the typical August vaccine ship date.
CDC and others are working to create the virus reference strain by the end of May that drug companies need to make a vaccine, says Bruce Gellin, director of HHS's National Vaccine Program Office and the agency's deputy assistant secretary for health. Once these companies make the necessary adjustments to their facilities and processes (which usually takes two or more weeks), he adds, they begin developing a pilot vaccine that the National Institutes of Health (NIH) tests to determine the amount of antigen per dose and number of doses, as well as information on safety.
"For a number of reasons, it is unlikely that [a swine flu vaccine] will be included in the seasonal vaccine," Gellin says. "As the seasonal vaccine is currently in the final phases of production, waiting for this additional strain would delay the availability of seasonal vaccine."
In addition, if the new vaccine requires two doses, it would complicate use of the seasonal vaccine as most (except children vaccinated for the first time) require only a single dose each year. "We may learn something from the clinical trials," he adds, "but the assumption going in is that a new virus that's not been seen in people before will require two doses."
Pharmaceuticals manufacturer Sanofi Pasteur, based in Lyon, France, agrees that the fastest and safest way to proceed is to maintain two separate vaccines for swine flu and for seasonal flu. "Production of the seasonal vaccine is well underway," company spokesperson Donna Cary says, confirming that attempts to combine vaccines would delay the seasonal vaccine.
While the extent of the current swine flu spread is yet to be seen, she adds, "we do know that seasonal influenza hospitalizes 200,000 people annually and resulted in about 36,000 deaths (in the U.S.) this year." The WHO and CDC meet in January each year to determine which influenza strains to include in that year's vaccine, which drug makers typically begin shipping in August.
Biotech firm Novavax, Inc. in Rockville, Md., is one of the few drug makers not waiting for the CDC to provide a live strain of the H1N1 virus. Instead, the company has begun developing a prototype swine flu vaccine using information the CDC has posted to the Global Initiative on Sharing Avian Influenza Data (GISAID) database, launched in 2006 by a number of science institutes and universities worldwide (including the WHO, CDC and Max-Planck-Institute for Informatics) to encourage data-sharing in response to the global spread of the H5N1 avian flu.
"The clock started last week on Friday," says Gale Smith, vice president of vaccine development for Novavax, which has seasonal flu vaccines in late-stage clinical testing but no products currently on the market.
Novavax claims to have developed a virus-like particle (VLP) technology that allows the company to manufacture a vaccine to match a particular virus strain in about three months. The recombinant VLPs, created without the use of any genetic material, contain surface proteins that make the particles look like a virus and can elicit an immune response, even though they lack the genes needed to replicate themselves.
Despite being a relative newcomer with a largely untested technique, Novavax is hoping to create a vaccine that could be given emergency approval for use by first responders, if no other vaccines are available, Smith says. The company plans to have a prototype vaccine to show the CDC or HHS within three months. Novavax's seasonal flu vaccine is currently in Phase III trials for efficacy and safety, but it could be years before that vaccine receives FDA approval.
As the vaccine makers await the materials needed get their products off the ground, London-based GlaxoSmithKline is ramping up production of its antiviral drug Relenza (zanamivir). Lab testing on oseltamivir (Tamiflu) and zanamivir indicates they could be up to 90 percent effective in staving off the current swine flu virus, according to the CDC. The swine influenza A (H1N1) viruses found in humans over the past week are resistant to the other two anti-influenza drugs on the market, amantadine (Symmetrel) and rimantadine (Flumadine).
Image of a number of H1N1 Influenza Virus particles © Dr. F. A. Murphy, Centers for Disease Control and Prevention
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