Monday, December 18, 2006
Cell culture-based vaccine could be more reliable and mass produced more quickly
Researchers at the University of Maryland School of Medicine in Baltimore will begin a clinical trial in January to test the first cell culture-based pandemic influenza vaccine to see if it will provide immunity faster and more reliably than a vaccine produced in eggs. The new study is also the first test in the United States of a whole virus vaccine for avian influenza, which could produce a stronger response by the immune system.
The Center for Vaccine Development at the University of Maryland School of Medicine is seeking healthy volunteers ages 18 to 40 years old to participate. The trial is funded by the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health.
“Our previous clinical trials have shown that the inactivated pandemic influenza vaccines against the H5N1 avian influenza strain are safe and stimulate an immune response that may protect people from avian flu,” says James Campbell, M.D., an assistant professor of pediatrics at the University of Maryland School of Medicine and principal investigator on the latest study. “This will be our first trial of a cell culture-based vaccine, and we are hopeful that it will provide a faster and more reliable immune response. The use of cell cultures could also provide for a larger manufacturing capacity and provide an option for people with egg allergies.”
The H5N1 influenza vaccines already tested at the University of Maryland School of Medicine and all FDA-approved influenza vaccines available in the United States are manufactured in eggs. “Viruses are grown in eggs before being inactivated (killed) and put into vaccine form,” he says. “People with egg allergies are not eligible to receive these vaccines.”
According to Dr. Campbell, whole virus vaccines like the new H5NI influenza vaccine about to be tested may stimulate better immune responses than traditional vaccines. “With whole vaccines, the viral particle, although not living, is still intact, which means the body’s immune system may respond better since the vaccine more closely resembles the natural virus,” he says. “The drawback is that people may experience a few more minor side effects with this type of vaccine, but it may be worth the additional discomfort if we are able to provoke better immune responses in more people with this version of the pandemic flu vaccine.”
The University of Maryland Center for Vaccine Development was first asked in April 2005 by the NIAID to test an inactivated pandemic influenza vaccine in preparation for a possible pandemic. That trial involved 450 volunteers at three sites across the country and showed that the vaccine was safe and elicited an immune response. Subsequent studies combined the vaccine with a compound called an adjuvant in order to improve immune responses. Results from those trials should be available later this year.
Current pandemic influenza vaccines are aimed at protecting people from infection with H5N1 influenza, an avian flu strain that was first seen in chickens and other birds in Hong Kong in 1997. People who have direct contact with these infected birds can contract the virus and become ill.
“The currently circulating H5N1 strains of avian flu can lead to severe disease in both birds and humans,” says Dr. Campbell. “Since this virus strain was first identified, there have been 258 cases of avian influenza in humans with 154 deaths. We are concerned that if this highly lethal virus becomes as contagious as the seasonal flu virus, it will spread quickly around the globe.”
During the new study, the Center for Vaccine Development will recruit up to 100 healthy adult volunteers between the ages of 18 and 40. Volunteers will have a medical screening, blood drawn several times and receive two vaccinations. Volunteers will be randomly assigned into six different dosage groups – five of the six groups will receive the cell culture-based H5N1 vaccine, and one of the six groups will receive a placebo. Compensation will be provided, and the study will last approximately eight months.
This latest pandemic influenza vaccine is manufactured by Baxter International. Those interested in volunteering for the study should call the Center for Vaccine Development at (410) 706-6156.
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