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Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in adults 65years of age and older: A phase II, observer-blind, randomized, controlled trial.

Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in adults 65years of age and older: A phase II, observer-blind, randomized, controlled trial.
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Madan A, Ferguson M, Rheault P, Seiden D, Toma A, Friel D, Soni J, Li P, Innis BL, Schuind A,


Madan A, Ferguson M, Rheault P, Seiden D, Toma A, Friel D, Soni J, Li P, Innis BL, Schuind A, (click to view)

Madan A, Ferguson M, Rheault P, Seiden D, Toma A, Friel D, Soni J, Li P, Innis BL, Schuind A,

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Vaccine 2017 03 1335(15) 1865-1872 pii S0264-410X(17)30270-0
Abstract
BACKGROUND
H7 influenza strains can cause severe and often fatal human infections, especially in the elderly. This phase II, observer-blind, randomized trial (www.ClinicalTrials.gov: NCT01949090) assessed the immunogenicity and safety of a novel AS03-adjuvanted H7N1 vaccine that may serve as a model H7-subtype vaccine.

METHODS
360 adults ≥65years of age in stable health received either 1 of 4 adjuvanted A/mallard/Netherlands/12/2000 split virion vaccine formulations (3.75μg or 7.5μg hemagglutinin adjuvanted with either AS03A or AS03B) or saline placebo, given as a 2-dose series. Immunogenicity was assessed using hemagglutination-inhibition (HI) and microneutralization (MN) assays for the per-protocol cohort, comprising 332 participants at 21days post-each dose, 332 at month 6, and 309 at month 12 (HI assay only). Safety was assessed up to month 12 for all participants who had received ≥1 dose (360 participants).

RESULTS
For H7N1 HI antibody assessment at day 42 (21days post-dose 2), seroprotection rates (SPR) in the vaccinated groups were 69.6%-88.7%, seroconversion rates (SCR) 69.6%-88.5%, mean geometric increase (MGI) 11.0-18.9, and HI geometric mean titers (GMTs) 55.0-104.8. These parameters declined by month 6 and month 12. Microneutralization GMTs were 46.2-74.7 in the vaccinated groups at day 42, while vaccine response rate (VRR; proportion with ≥4-fold increase in MN titer) was 46.4%-81.5%. For the cross-reactive H7N9 strain, at day 42, HI GMT were 64.3-201.3, SPR 78.6%-96.3%, SCR 79.3%-96.3%, and MGI 14.1-37.7; MN GMTs were 44.0-85.6, and VRR 46.4-85.2%. The most frequent solicited symptom was injection site pain (41.7%-65.0% of vaccine recipients). In total, 40 participants reported 67 serious adverse events; none were considered causally related to vaccination.

CONCLUSIONS
In adults aged ≥65years, the adjuvanted H7N1 vaccine was immunogenic after 2 doses, and had an acceptable safety profile. www.ClinicalTrials.gov: NCT01949090.

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