A trial revealed that the AS03 and MF59 adjuvants increased the immune responses to two doses of an inactivated H7N9 influenza vaccine, according to a Science Daily news report.
Lisa A. Jackson, M.D., M.P.H., of Group Health Research Institute, Seattle, and colleagues randomly assigned 980 adults (19 through 64 years or age) to receive the H7N9 vaccine on days 0 and 21 at doses of 3.75 µg, 7.5 µg, 15 µg, and 45 µg of hemagglutinin with or without AS03 or MF59 adjuvant. The study was conducted at 5 U.S. sites from September 2013 through November 2013; safety follow-up was completed in January 2015.
Two doses of vaccine were required to induce detectable antibody titers in most participants. After 2 doses of an H7N9 formulation containing 15 µg of hemagglutinin given without adjuvant, with AS03 adjuvant, or with MF59 adjuvant, the proportion achieving an hemagglutination inhibition antibody (HIA) titer of 40 or higher was 2 percent without adjuvant (n = 94), 84 percent with AS03 adjuvant (n = 96), and 57 percent with MF59 adjuvant (n = 92).
The two schedules alternating AS03-and MF59-adjuvanted formulations led to lower geometric mean (average) titers (GMTs) than the group induced by two AS03-adjuvanted formulations but higher GMTs than two doses of MF59-adjuvanted formulation. Older age and prior administration of seasonal influenza vaccine were independently associated with a decreased antibody response.