FRIDAY, Aug. 17 (HealthDay News) -- Low doses of an H5N1 avian influenza vaccine are still effective when combined with a new type of adjuvant, researchers report in the Aug. 18 issue of The Lancet. This type of antigen sparing could boost production capacity in the event of a pandemic and could potentially be used before a pandemic strikes, the study found.
Geert Leroux-Roels, M.D., of Ghent University and Hospital in Ghent, Belgium, and colleagues administered two doses of an inactivated split vaccine derived from a strain of the virus originating in Vietnam to eight groups of 50 volunteers aged 18 to 60 years. The vaccines were administered 21 days apart in one of four doses: 3.8 μg, 7.5 μg, 15 μg, and 30 μg hemagglutinin with or without adjuvant. The adjuvant is ASO3, a proprietary formulation containing non-ionic detergent polysorbate 80 and DL-alpha-tocopherol squalene.
The safety profile was good for all eight groups and there were no serious adverse events, although there were more mild and transitory side-effects from the adjuvanted vaccines than the non-adjuvanted batches. At the lowest dose the adjuvanted vaccine produced an adequate immune response and in 37 out of 48 subjects also neutralized antibodies from a drifted H5N1 isolate from Indonesia.
"The cross-clade neutralizing antibody responses recorded imply that such a vaccine could be deployed before pandemic outbreak," the authors write. "However, further analyses are warranted to confirm whether it could also confer high degrees of cross-protection against other pandemic drift strains."
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