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

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.

Immunogenicity and safety of an AS03-adjuvanted H7N1 vaccine in healthy adults: A phase I/II, observer-blind, randomized, controlled trial.

BACKGROUND: H7 influenza strains have pandemic potential. AS03-adjuvanted H7N1 A/mallard/Netherlands/12/2000 split-virion vaccine formulations were evaluated as model H7-subtype vaccine and tested after H7N9 emerged in China, and caused severe human disease with high mortality. METHODS: In this phase I/II, observer-blind, randomized trial in US and Canada, 420 healthy adults (21-64years) were randomized to receive 1 of 4 H7N1 vaccine formulations (3.75 or 7.5µg hemagglutinin adjuvanted with either AS03A or AS03B), 15µg unadjuvanted H7N1 hemagglutinin, or saline placebo, given as 2-dose series. Immunogenicity was assessed using hemagglutination-inhibition (HI) and microneutralization (MN) assays, at day 42 (21days post-dose 2), month 6, and month 12 (HI only) for the per-protocol cohorts (398, 379 and 368 participants, respectively). Safety is reported up to month 12. RESULTS: Beneficial AS03 adjuvant effect was demonstrated. Committee for Medical Products for Human Use, and Center for Biologics Evaluation and Research (CBER) criteria were met for all adjuvanted formulations at day 42 (H7N1 HI assay); seroprotection (SPR) and seroconversion rates (SCR) were 88.5-94.8%, mean geometric increase (MGI) 19.2-34.9, and geometric mean titers (GMT) 98.3-180.7. Unadjuvanted H7N1 vaccine did not meet CBER criteria. In adjuvanted groups, antibody titers decreased over time; month 12 SPRs and GMTs were low (2.0-18.8% and 8.1-12.2). MN antibodies showed similar kinetics, with titers persisting at higher range than HI at month 6. All adjuvanted groups showed cross-reactivity against H7N9, with HI responses similar to H7N1. The most frequent solicited symptom in adjuvanted groups was injection site pain (71.2-86.7%); grade 3 solicited symptoms were infrequent. Nine participants reported 17 serious adverse events; none were considered causally related to vaccination. CONCLUSIONS: Adjuvanted H7N1 vaccine formulations had an acceptable safety profile and induced an antibody response after 2 doses with cross-reactivity to H7N9. ClinicalTrials.gov: NCT01934127.

Immunogenicity and Safety of an AS03-Adjuvanted H7N9 Pandemic Influenza Vaccine in a Randomized Trial in Healthy Adults.

BACKGROUND: Almost 700 cases of human infection with avian influenza A/H7N9 have been reported since 2013. Pandemic preparedness strategies include H7N9 vaccine development. METHODS: We evaluated an inactivated H7N9 vaccine in an observer-blind study in healthy adults aged 18-64 years. Participants (420) were randomized to receive 1 of 4 AS03-adjuvanted vaccines (low or medium dose of hemagglutinin with AS03A or AS03B), one nonadjuvanted vaccine, or placebo. The coprimary immunogenicity objective determined whether adjuvanted vaccines elicited an immune response against the vaccine-homologous virus, 21 days after the second vaccine dose per US and European licensure criteria in the per-protocol cohort (n = 389). RESULTS: All adjuvanted vaccines met regulatory acceptance criteria. In groups receiving adjuvanted formulations, seroconversion rates were ≥85.7%, seroprotection rates ≥91.1%, and geometric mean titers ≥92.9% versus 23.2%, 28.6%, and 17.2 for the nonadjuvanted vaccine. The AS03 adjuvant enhanced immune response at antigen-sparing doses. Injection site pain occurred more frequently with adjuvanted vaccines (in ≤98.3% of vaccinees) than with the nonadjuvanted vaccine (40.7%) or placebo (20.0%). None of the 20 serious adverse events reported were related to vaccination. CONCLUSIONS: Two doses of AS03-adjuvanted H7N9 vaccine were well tolerated and induced a robust antibody response at antigen-sparing doses in healthy adults. CLINICAL TRIALS REGISTRATION: NCT01999842.

Safety and long-term humoral immune response in adults after vaccination with an H1N1 2009 pandemic influenza vaccine with or without AS03 adjuvant.

BACKGROUND: In this study (NCT00985088) we evaluated different formulations of an H1N1 2009 pandemic influenza vaccine that deliver various viral hemagglutinin (HA) doses with or without AS03 (a tocopherol-based oil-in-water adjuvant system). METHODS: A total of 1340 healthy subjects aged ≥18 years were randomized to receive 1 or 2 doses of an adjuvanted (3.75-µg HA/AS03(A) or 1.9-µg HA/AS03(B)) or nonadjuvanted vaccine formulation. Safety and immunogenicity (by hemagglutination-inhibition [HI] assay) after each dose and 6 months after dose 1 are reported here. RESULTS: A single dose of AS03(A)-adjuvanted 3.75-µg HA H1N1 2009 induced the strongest immune responses in subjects aged 18-64 years (seroprotection rate [SPR], 97.2%; seroconversion rate [SCR], 90.1%) as well as in subjects aged >64 years (SPR, 91.1%; SCR, 78.2%) 21 days after vaccination. Six months after dose 1, subjects who received 2 doses of either the adjuvanted formulation or 1 dose of the adjuvanted 3.75-µg HA formulation continued to meet all Center for Biologics Evaluation and Research and Committee for Medicinal Products for Human Use criteria. All formulations had clinically acceptable safety profiles. CONCLUSION: A single dose of the 3.75-µg HA AS03(A)-adjuvanted H1N1 2009 influenza vaccine was highly immunogenic in both age strata (18-64 and >64 years), inducing long-term persistence of the immune response until at least 6 months after dose 1.