Research Indicates Bird Flu Vaccines Can Benefit From Use Of Adjuvants

Chuck Bednar for redOrbit.com – Your Universe Online
The authors of two new studies published Wednesday in the Journal of the American Medical Association (JAMA) analyzed the use of different types of vaccines to help better prevent and control pandemic bird flu virus.
In one of the studies, Saint Louis University professor of infectious diseases, allergy and immunology Dr. Robert Belshe and his colleagues found that a vaccine designed to protect against an old strain of avian flu helped prepare a person’s immune system to rapidly respond when a vaccine designed to protect against a different and newer form of the virus was given one year later.
Furthermore, when a lower dose of the new avian flu vaccine is combined with an adjuvant (a chemical that causes a person’s immune system to produce more antibodies), it worked better in triggering an immune response than a stronger dose of the vaccine without the adjuvant. What that essentially means is the vaccine against the newer form of the flu can be combined with an adjuvant to make it stretch further and allow more people to be vaccinated.
Dr. Belshe explained that both of these findings represent key strategies researchers can use to continue analyzing how to help combat new strains of avian flu which people have yet to be exposed to, and which could consequently spread into a pandemic outbreak and potential health emergency. Since planning for influenza pandemics is vitally important, he said the research can help experts respond quickly to potential health threats.
The authors looked at two different two H5 influenza vaccines, and recruited 637 healthy adults between the ages of 18 and 49 at eight clinical sites throughout the US. Some of the participants had previously been given one or two doses of Vietnam bird flu vaccine as part of a previous study, and those individuals had developed “an immunologic memory” when they received a booster dose of a new, investigational Anhui bird flu vaccine, Dr. Belshe said.
Previously unvaccinated volunteers received various doses of the new Ahnui bird flu vaccine, the researchers noted. Two doses were needed to stimulate an antibody response in the previously unvaccinated participants, and when paired with the immune-system boosting adjuvant, a 7.5 microgram dose of Anhui vaccine was found to be more effective in eliciting an immune response against bird flu that a higher 90 microgram dose without the adjuvant.
In the second study, a team of researchers led by Dr. Mark J. Mulligan of Emory University School of Medicine in Atlanta conducted a clinical trial of an experimental H7N9 avian influenza vaccine, and found that it was believed to be protective in 59 percent of study participants who received two injections of the vaccine at the lowest dosage when mixed with an adjuvant to boost immune response.
However, without the adjuvant, the National Institute of Allergy and Infectious Diseases (NIAID)-sponsored study of 700 healthy adults between the ages of 19 and 64 found that those who received the vaccine had a minimal immune response, regardless of how large a dosage of the investigational vaccine they received, the agency revealed in a statement Tuesday.
The volunteers were divided into groups based on the dosage of vaccine they received and whether or not they were given an adjuvant (MF59) at the start of the trial and three weeks into it. Those receiving the vaccine without adjuvant had minimal immune response, even at the highest vaccine dosages, based on an assessment after 42 days with a standardized blood test known as the hemagglutination (HAI) antibody assay.
“This clinical trial gave us valuable information about the use of H7N9 flu vaccine combined with adjuvant and makes us better prepared for a potential pandemic,” Dr. Mulligan said in a statement. “We must continue to test and improve vaccines for all flu strains, as these viruses have the ability to mutate and spread rapidly.”
In an editorial accompanying the two studies, Dr. John J. Treanor of the University of Rochester said the research will help “provide important information that expands the available options for confronting pandemic influenza, and may help surmount those obstacles,” and that the two papers – along with other studies like them – effectively demonstrate that “a prepandemic vaccination program is certainly feasible.”
—–