Details of the Fluarix clinical study are discussed in the November/December 2005 issue of Human Vaccines, available online December 22.
Clinical testing of the seasonal influenza vaccine Fluarix began in December 2004 as an effort to augment the future U.S. flu vaccine supply, which was experiencing an unexpected, significant shortage. Fluarix, which is manufactured by GlaxoSmithKline Biologicals of Rixensart, Belgium, had been approved in 1998 for use in other countries but had never been tested or licensed for use in the United States.
The vaccine was evaluated in a clinical trial involving nearly 1,000 healthy adults at four sites nationwide. Clinical evaluation of the candidate vaccine was performed under an FDA-reviewed "investigational new drug" application, in which potential study volunteers are fully informed about potential risks and benefits and must provide their informed consent before receiving the investigational product. The clinical trial was rapidly initiated and reached capacity enrollment within five days of its launch in December 2004.
"The Fluarix study is an excellent example of what government and industry can accomplish in a short timeframe when faced with a serious public health need," says NIH Director Elias A. Zerhouni, M.D.
"This effort is a model for the type of effective collaboration that will be needed to produce vaccines in the event of an influenza pandemic," adds NIAID Director Anthony S. Fauci, M.D.
"There was real synergy between academia, which supplied the clinical trial infrastructure; NIH, which supplied the necessary funding and direction; industry, which had the desire to bring Fluarix to the U.S. market; and the FDA, which agreed to review the study results in a speedy fashion," states lead investigator John Treanor, M.D., of the University of Rochester Medical Center, one of the four NIAID-sponsored Vaccine Treatment and Evaluation Units (VTEUs) that conducted the study. "The end result was that we now have 8 million doses of a new flu vaccine available in the U.S. for the 2005-2006 flu season."
In addition to the University of Rochester, the 30-day clinical study was conducted at the following VTEUs: Cincinnati Children's Hospital; University of Maryland School of Medicine, Baltimore; and Baylor College of Medicine. The study participants included 952 healthy adults ages 18 to 64 years old; 760 received a single dose of the 0.5-ml vaccine while 192 received placebo. Those who received the placebo were offered the U.S.-licensed flu vaccine at the conclusion of the study.
Researchers observed the study participants for adverse events immediately following vaccination and provided them with diary cards to record any reactions that occurred during the three subsequent days following immunization. According to the study findings, the vaccine was well-tolerated with redness and mild-to-moderate pain at the injection site as the most common reported adverse events. Importantly, symptoms patients might expect after influenza vaccination, such as headache, fatigue, chills and fever, were no different between those who received the vaccine and those who received the placebo--verification that inactivated influenza vaccines such as Fluarix do not cause influenza.
To determine immune system response to the vaccine, researchers collected serum samples from the study participants both prior to vaccination and 21 days afterward. "The vaccine performed extremely well and very similarly to other influenza vaccines already licensed in the U.S.," notes Dr. Treanor. "It wasn't surprising considering Fluarix is widely used in Europe and has a long safety record there."
Because annual flu shots are generally recommended for adults ages 50 to 64 years old, the researchers analyzed separately the antibody levels of trial participants ages 18 to 49 and those ages 50 to 64 to compare immune responses. While the vaccine was found to produce an immune response in both groups, antibody response rates were higher in the younger study group, particularly those who had no history of flu vaccination within the previous three years.
"This trial provided confirmatory evidence of something we already suspected: that age has an effect on immune response," says Dr. Treanor.
The FDA granted Fluarix licensure under its accelerated approval regulations that allow products designed to treat serious or life-threatening illnesses to be approved based on clinical trial data demonstrating their ability to achieve a specific clinical endpoint that is likely to predict effectiveness--usually one that can be studied more rapidly than showing protection against disease. The Fluarix study demonstrated that after vaccination, study volunteers produced protective antibodies in the blood that the FDA assessed were highly likely to predict effectiveness in preventing flu.
The research was also supported through a grant from the National Center for Research Resources, part of NIH. A press release issued at the December 2004 launch of the NIAID-sponsored Fluarix clinical trial is available at http://www3.niaid.nih.gov/news/newsreleases/2004/gskflu.htm.
NIAID is a component of the National Institutes of Health, an agency of the U.S. Department of Health and Human Services. NIAID supports basic and applied research to prevent, diagnose and treat infectious diseases such as HIV/AIDS and other sexually transmitted infections, influenza, tuberculosis, malaria and illness from potential agents of bioterrorism. NIAID also supports research on transplantation and immune-related illnesses, including autoimmune disorders, asthma and allergies.
Reference: J. Treanor et al. Rapid licensure of a new, inactivated influenza vaccine in the United States. Human Vaccines. Published online December 22, 2005. Appearing in the November/December 2005 print edition.
News releases, fact sheets and other NIAID-related materials are available on the NIAID Web site at http://www.niaid.nih.gov.
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