Translation from Preclinical Research to Clinical Trials: Brain-Gut Photobiomodulation Therapy for Alzheimer's Disease.

Recently, novel non-pharmacological interventions, such as photobiomodulation (PBM) therapy, have shown promise for the treatment of Alzheimer's disease (AD). This article outlines the translation from the preclinical to clinical stages of an innovative brain-gut PBM therapy in a mouse model of AD, a pilot clinical trial involving mild-to-moderate AD patients, and a continuing pivotal clinical trial with a similar patient population. In a mouse model of AD (Aß25-35), daily application of brain-gut PBM therapy to both the head and the abdomen produced a neuroprotective effect against the neurotoxic effects of an Aß25-35 peptide injection by normalizing all the modified behavioral and biochemical parameters. The pilot clinical trial to evaluate brain-gut PBM therapy demonstrated the tolerability and feasibility of the novel PBM-based treatment for mild-to-moderate AD patients. Compared to the sham patients, the PBM-treated patients had lower Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) comprehension sub-scores, higher forward verbal spans, and lower Trail Making Test (TMT) Part B (TMT-B) execution times, which suggest an improvement in cognitive functions. This pilot study provided important information for the design of a novel pivotal clinical trial, currently in progress, to assess the efficacy of brain-gut PBM therapy in a larger sample of AD patients. This pivotal clinical trial could demonstrate that brain-gut PBM therapy is a safe, well-tolerated, and efficient disease-modifying treatment for mild-to-moderate AD patients and that it has medical and economic benefits.

Strain specific stress-modulating effects of candidate probiotics: A systematic screening in a mouse model of chronic restraint stress.

BACKGROUND: Changes in the gut microbiota have been implicated in mood and cognition. In rodents, supplementation with certain bacteria have been shown to alleviate adverse effects of stress on gut microbiota composition and behaviour, but little is known of how the performance of different strains compare to each other. We took a systematic approach to test the efficacy of twelve candidate probiotic strains from ten species/sub-species of Bifidobacterium and Lactobacillus on behaviours and neuroendocrine responses of chronically stressed mice. METHODS: The strains were tested in four screening experiments with non-stressed and chronically stressed vehicle groups. The three most efficacious strains were re-tested to validate the results. Mice were administered a daily oral gavage containing either 1 × 109 colony forming units (CFU) of selected candidate probiotic or saline solution for one week prior to and for three weeks during daily chronic restraint stress. Behavioural tests including the elevated plus maze, open field, novel object recognition, and forced swim test were applied during week five. Corticosterone and adrenocorticotropic hormone (ACTH) were analysed to measure the neuroendocrine response to stress. Plasma and tissue samples were collected for biomarker analyses. RESULTS: Of the twelve candidate probiotics, Lactobacillus paracasei Lpc-37, Lactobacillus plantarum LP12407, Lactobacillus plantarum LP12418 and Lactobacillus plantarum LP12151 prevented stress-associated anxiety and depression-related behaviours from developing compared with chronically stressed vehicle mice. In addition, Lpc-37 improved cognition. CONCLUSION: This systematic screening indicates species- and strain-dependent effects on behavioural outcomes related to stress and further suggests that strains differ from each other in their effects on potential mechanistic outcomes.

Long-term outcome of the humoral and cellular immune response of an H5N1 adjuvanted influenza vaccine in elderly persons: 2-year follow-up of a randomised open-label study.

BACKGROUND: Older individuals often have a reduced immune response to influenza vaccination, which might be improved by administering a higher vaccine dose. We compared the immune response to two single doses of the AS03A-adjuvanted H5N1 pandemic vaccine (3.75 µg hemagglutinin of A/Vietnam/1194/2004) with that of two double vaccine doses (7.5 µg hemagglutinin) in adults aged ≥61 years. Here we report the 2-year persistence of the humoral and cellular immune response. METHODS: In this phase II, open-label study, healthy participants aged 61 to 88 years (median 68 years) were randomised (3:1:3:1) to receive two single doses of the AS03A-adjuvanted vaccine (1xH5N1-AS) or the non-adjuvanted vaccine (1xH5N1), or two double doses of the AS03A-adjuvanted vaccine (2xH5N1-AS) or the non-adjuvanted vaccine (2xH5N1), 21 days apart. Serum haemagglutination inhibition antibodies and cellular immune responses against A/Vietnam/1194/2004 were measured in all groups at months 12 and 24; neutralising antibodies were assessed in a subset of the adjuvanted groups. Serious adverse events and adverse events of specific interest were recorded. RESULTS: At month 24, haemagglutination inhibition antibody seroprotection rates were 37.2% (95% CI 27.0% to 48.3%) for 1xH5N1-AS, 30.9% (95% CI 21.1% to 42.1%) for 2xH5N1-AS, 16.2% (95% CI 6.2% to 32.0%) for 1xH5N1, and 8.3% (95% CI 1.0% to 27.0%) for 2xH5N1. Haemagglutination inhibition antibody geometric mean titres were 17.6 (95% CI 13.7 to 22.5) for 1xH5N1-AS, 18.4 (95% CI 14.2 to 23.8) for 2xH5N1-AS, 12.3 (95% CI 8.9 to 16.9) for 1xH5N1 and 9.8 (95% CI 6.7 to 14.4) for 2xH5N1. The median frequency of antigen-specific CD4+ T cells per 106 T cells (25th quartile; 75th quartile) was 852 (482; 1477) for 1xH5N1-AS, 1147 (662; 1698) for 2xH5N1-AS, 556 (343; 749) for 1x-H5N1 and 673 (465; 1497) for 2xH5N1. Neutralising antibody geometric mean titres were 391.0 (95% CI 295.5 to 517.5) in the 1xH5N1-AS group and 382.8 (95% CI 317.4 to 461.6) in the 2xH5N1-AS group. CONCLUSIONS: Antibody levels declined substantially in all groups. Seroprotection rates, geometric mean titres for haemagglutination inhibition antibodies, and CD4+ T-cell responses tended to be higher in the AS03A-adjuvanted groups. There was no clear benefit, in terms of long-term persistence of the immune response, of doubling the dose of the adjuvanted vaccine. No safety concern was observed up to 24 months post-primary vaccination. TRIAL REGISTRATION: NCT00397215 (7 November 2006).

Long-term booster schedules with AS03A-adjuvanted heterologous H5N1 vaccines induces rapid and broad immune responses in Asian adults.

BACKGROUND: The pandemic potential of avian influenza A/H5N1 should not be overlooked, and the continued development of vaccines against these highly pathogenic viruses is a public health priority. METHODS: This open-label extension booster study followed a Phase III study of 1206 adults who had received two 3.75 µg doses of primary AS03A-adjuvanted or non-adjuvanted H5N1 split-virus vaccine (A/Vietnam/1194/2004; clade 1) (NCT00449670). The aim of the extension study was to evaluate different timings for heterologous AS03A-adjuvanted booster vaccination (A/Indonesia/5/2005; clade 2.1) given at Month 6, 12, or 36 post-primary vaccination. Immunogenicity was assessed 21 days after each booster vaccination and the persistence of immune responses against the primary vaccine strain (A/Vietnam) and the booster strain (A/Indonesia) was evaluated up to Month 48 post-primary vaccination. Reactogenicity and safety were also assessed. RESULTS: After booster vaccination given at Month 6, HI antibody responses to primary vaccine, and booster vaccine strains were markedly higher with one dose of AS03A-H5N1 booster vaccine in the AS03A-adjuvanted primary vaccine group compared with two doses of booster vaccine in the non-adjuvanted primary vaccine group. HI antibody responses were robust against the primary and booster vaccine strains 21 days after boosting at Month 12 or 36. At Month 48, in subjects boosted at Month 6, 12, or 36, HI antibody titers of ≥1:40 against the booster strain persisted in 39.2%, 61.2%, and 95.6% of subjects, respectively. Neutralizing antibody responses and cell-mediated immune responses also showed that AS03A-H5N1 heterologous booster vaccination elicited robust immune responses within 21 days of boosting at Month 6, 12, or 36 post-primary vaccination. The booster vaccine was well tolerated, and no safety concerns were raised. CONCLUSIONS: In Asian adults primed with two doses of AS03A-adjuvanted H5N1 pandemic influenza vaccine, strong cross-clade anamnestic antibody responses were observed after one dose of AS03A-H5N1 heterologous booster vaccine given at Month 6, 12, or 36 after priming, suggesting that AS03A-adjuvanted H5N1 vaccines may provide highly flexible prime-boost schedules. Although immunogenicity decreased with time, vaccinated populations could potentially be protected for up to three years after vaccination, which is likely to far exceed the peak of the a pandemic.

Long-term persistence of humoral and cellular immune responses induced by an AS03A-adjuvanted H1N1 2009 influenza vaccine: an open-label, randomized study in adults aged 18-60 years and older.

This manuscript presents data on the persistence of Hemagglutination Inhibition (HI) immune response against the A/California/7/2009 strain, six and 12 mo after adults received one dose (n = 138) or two doses (n = 102; 21 d apart) of a 3.75 µg Hemagglutinin antigen AS03-adjuvanted H1N1 2009 vaccine (NCT00968526). Two hundred forty subjects (18-60 y: 120;>60 y: 120) were vaccinated. Immunogenicity end points were based on the European licensure criteria for pandemic influenza vaccines. Exploratory analyses assessed the cell-mediated immune response (CMI) up to Month 12 and the influence of previous influenza vaccination on persistence of immune response. At Month 6, the CHMP criteria were met in subjects aged 18-60 y who received one or two vaccine doses and in subjects aged>60 y who received two vaccine doses. At Month 12, the CHMP criteria were met only in subjects aged 18-60 y who received two vaccine doses. Persistence of HI immune response against the vaccine strain was higher in subjects without prior influenza vaccination. Exploratory analyses showed that two doses of the H1N1 2009 vaccine induced persistence of H1N1-specific CD4+ T cells up to Month 6 and memory B cells up to Month 12. In conclusion, HI immune responses persisted up to 12 mo after vaccination with one-dose and two-dose regimens of the AS03-adjuvanted 3.75 µg HA H1N1 2009 pandemic influenza vaccine, although not all three CHMP guidance criteria for both groups were met at Month 6 and Month 12. The CD4+ T cell and B cell responses also persisted up to Month 12.

An assessment of prime-boost vaccination schedules with AS03A -adjuvanted prepandemic H5N1 vaccines: a randomized study in European adults.

BACKGROUND: Long-term persistence of immune response and safety of an H5N1 prepandemic influenza vaccine adjuvanted with AS03 (an α-tocopherol oil-in-water emulsion-based adjuvant system) was evaluated using various prime-boost schedules that mimicked potential pandemic scenarios (NCT00430521). METHODS: Five hundred and twelve healthy adults aged 18-60 years received primary vaccination with one or two doses (0, 21 days schedule) of the A/Vietnam/1194/2004 H5N1 vaccine followed by a booster dose (A/Vietnam/1194/2004 or A/Indonesia/05/2005 strain) six or twelve months later across eight randomized groups. Immunogenicity results by hemagglutination inhibition [HI] assay, microneutralization assay, and the cell-mediated immune response (CMI) are reported here for the four groups boosted at Month 12. RESULTS: A one-dose-adjuvanted primary administration followed 12 months later by a single-adjuvanted booster dose containing a heterologous vaccine strain met or exceeded all US and European criteria for both strains. Increasing the interval between the first and second dose (from 21 days to 12 months) resulted in stronger cross-reactive immune responses against the A/Indonesia/05/2005 strain. The HI antibody response against the two strains persisted for 6 months after the booster dose irrespective of the booster vaccine's strain. The neutralizing antibody responses and the CMI observed in the study population paralleled the HI immune response. Overall, the vaccine had a clinically acceptable safety profile. CONCLUSION: The H5N1 vaccine in this study allowed for flexibility in the time interval between primary and booster vaccination and the use of a heterologous strain without impacting the strength of the humoral and cellular immune response to both vaccine strains.

Long-term immunogenicity of two doses of 2009 A/H1N1v vaccine with and without AS03(A) adjuvant in HIV-1-infected adults.

OBJECTIVE: In immunocompromised patients, alternative schedules more immunogenic than the standard influenza vaccine regimen are necessary to enhance and prolong vaccine efficacy. We previously reported that the AS03A-adjuvanted 2009 A/H1N1v vaccine yielded a higher short-term immune response than the nonadjuvanted one in HIV-1-infected adults. This study reports the long-term persistence of the immune response. DESIGN AND METHODS: In a prospective, multicenter, randomized, patient-blinded trial, two doses of AS03A-adjuvanted H1N1v vaccine containing 3.75 µg haemagglutinin (n = 155; group A) or nonadjuvanted H1N1v vaccine containing 15 µg haemagglutinin (n = 151; group B), were administered 21 days apart. Haemagglutination inhibition and neutralizing antibodies were assessed 6 and 12 months after vaccination. RESULTS: In group A and B, the seroprotection rates were 83.7 and 59.4% at month 6, and 70.4 and 49.3 at month 12, respectively. In a multivariate analysis, persistence of seroprotection 12 months after vaccination was negatively associated with current smoking (odds ratio = 0.6, P = 0.03) and positively related with the AS03A-adjuvanted H1N1v vaccine (odds ratio = 2.7, P = 0.0002). CONCLUSION: In HIV-1-infected adults, two doses of adjuvanted influenza vaccine induce long-term persistence of immune response up to 1 year after vaccination.

Safety and persistence of immunological response 6 months after intramuscular vaccination with an AS03-adjuvanted H1N1 2009 influenza vaccine: an open-label, randomized trial in Japanese children aged 6 months to 17 years.

This study evaluated the long-term persistence of immune response and safety of two doses of an A/California/7/2009 H1N1 pandemic influenza vaccine adjuvanted with AS03 (an α-tocopherol oil-in-water emulsion-based Adjuvant System) in Japanese children (NCT01001169). Sixty healthy subjects aged 6 mo-17 y were enrolled (1:1) into two study groups to receive 21 d apart, two doses of 1.9 µg haemagglutinin [HA]+AS03B (5.93 mg α-tocopherol) vaccine (6 mo-9 y) and 3.75 µg HA+AS03A (11.86 mg α-tocopherol) vaccine (10-17 y), respectively. Immunogenicity data (by haemagglutination inhibition [HI] and microneutralisation assays) to six months after the first vaccine dose are reported here. It was observed that following Dose 2, the HI immune response against the vaccine homologous strain induced by the two different dosages of the AS03-adjuvanted vaccine met and exceeded the US and European regulatory guidance criteria for pandemic influenza vaccines (seroprotection rate[SPR]/seroconversion rate[SCR]: 100%/100%; geometric mean fold rise GMFR: 146.8/57.1). Further, the immune response persisted for at least six months after the first vaccine dose wherein these regulatory criteria were still met (SPR: 100%/100%; SCR: 96.4%/89.7%; GMFR: 25.3/23.5). The neutralising antibody response was comparable to the HI immune response at Day 42 (vaccine response rate [VRR]: 100%/100%) and at Day 182 (VRR: 96.4%/82.8%). Overall, both vaccine dosages had a clinically acceptable safety profile. Thus, two doses of a 1.9 µg or 3.75 µg HA AS03-adjuvanted H1N1 2009 pandemic influenza vaccine in children aged 6 mo-17 y induced strong immune responses against the vaccine homologous strain that persisted for at least six months after the first vaccine dose.

Characterization and long-term persistence of immune response following two doses of an AS03A-adjuvanted H1N1 influenza vaccine in healthy Japanese adults.

Background Long-term persistence of immune response and safety of two doses of an A/California/07/2009 H1N1 pandemic influenza vaccine adjuvanted with AS03 (an α-tocopherol oil-in-water emulsion-based Adjuvant System) administered 21 d apart was evaluated in Japanese adults [NCT00989612]. Methods One-hundred healthy subjects aged 20-64 y (stratified [1:1] into two age strata 20-40 y and 41-64 y) received 21 d apart, two doses of AS03-adjuvanted 3.75µg haemagglutinin (HA) H1N1 2009 vaccine. Immunogenicity data by haemagglutination inhibition (HI) assay six months after the first vaccine dose (Day 182) and microneutralization assay following each of the two vaccine doses (Days 21 and 42) and at Day 182 are reported here. Results Persistence of strong HI immune response was observed at Day 182 that met the US and European regulatory thresholds for pandemic influenza vaccines (seroprotection rate: 95%; seroconversion rate: 93%; geometric mean fold-rise: 20). The neutralizing antibody response against the A/Netherlands/602/2009 strain (antigenically similar to vaccine-strain) persisted for at least up to Day 182 (vaccine response rate: 76%; geometric mean titer: 114.4) and paralleled the HI immune response at all time points. No marked difference was observed in HI antibody persistence and neutralising antibody response between the two age strata. The vaccine had a clinically-acceptable safety profile. Conclusion Two priming doses of H1N1 2009 pandemic influenza vaccine induced an immune response persisting for at least six months after the first vaccine dose. This could be beneficial in evaluating the importance and effect of vaccination with this AS03-adjuvanted pandemic influenza vaccine.

Effect on cellular and humoral immune responses of the AS03 adjuvant system in an A/H1N1/2009 influenza virus vaccine administered to adults during two randomized controlled trials.

The influence of AS03(A), a tocopherol oil-in-water emulsion-based adjuvant system, on humoral and cell-mediated responses to A/California/7/2009 H1N1 pandemic vaccine was investigated. In two observer-blind studies, a total of 261 healthy adults aged 18 to 60 years were randomized to receive either AS03(A)-adjuvanted H1N1 vaccine containing 3.75 µg hemagglutinin (HA) or nonadjuvanted H1N1 vaccine containing 15 or 3.75 µg HA on days 0 and 21. Hemagglutination inhibition (HI) antibody and T-cell responses were analyzed up to day 42. A first dose of AS03(A)-adjuvanted vaccine (3.75 µg HA) or nonadjuvanted vaccine (15 µg HA) induced HI responses of similar magnitudes that exceeded licensure criteria (e.g., 94 to 100% with titers of ≥ 40). A lower response following 3.75 µg HA without adjuvant was observed (73% with titers of ≥ 40). Following a second dose, geometric mean HI titers at day 42 were higher for AS03(A)-adjuvanted vaccine (636 and 637) relative to nonadjuvanted vaccine (341 for 15 µg HA and 150 for 3.75 µg HA). Over the 42-day period, the increase in frequency of A/H1N1/2009-specific CD4⁺ T cells was significantly higher in the adjuvanted group than in the nonadjuvanted group. There was no evidence of correlation between baseline CD4⁺ T-cell frequencies and day 21 HI antibody titers, while there was some correlation (R = 0.35) between day 21 CD4⁺ T-cell frequencies and day 42 HI titers. AS03(A) adjuvant enhanced the humoral and CD4⁺ T-cell-mediated responses to A/H1N1/2009 vaccine. Baseline A/H1N1/2009-specific CD4⁺ T-cell frequencies did not predict post-dose 1 antibody responses, but there was some correlation between post-dose 1 CD4⁺ T-cell frequencies and post-dose 2 antibody responses.

Immunogenicity and safety of an AS03(A)-adjuvanted H5N1 influenza vaccine in a Taiwanese population.

BACKGROUND/PURPOSE: A multicenter study (NCT00449670) conducted across Taiwan, Singapore, Hong Kong and Thailand evaluated the safety and manufacturing consistency of four formulations of an AS03(A)-adjuvanted H5N1 vaccine in terms of immune response against the vaccine-homologous strain (A/Vietnam/1194/2004). This manuscript presents data from the Taiwanese population. METHODS: A total of 400 individuals, aged 18-60 years, were randomized into six groups (2:2:2:2:1:1 ratio) to receive two doses (21 days apart) of one of the four adjuvanted formulations (H5N1-AS03(A)-groups) or one of the two nonadjuvanted formulations (H5N1-DIL-groups). Blood samples collected before vaccination (Day 0) and 21 days after each vaccine dose were analyzed using hemagglutination inhibition (HI) assay. Adverse events were recorded. RESULTS: All four AS03(A)-adjuvanted formulations induced comparable immune responses against the A/Vietnam/1194/2004 strain; following the second dose, immune response in terms of HI antibodies was higher in the H5N1-AS03(A)-groups {seroprotection rate=91.6% [95% confidence interval (CI): 87.9-94.4]; geometric mean titer (GMT)=177.6 (95% CI: 153.2-206.0)} compared with the H5N1-DIL-groups [seroprotection rates=5.0% (95% CI: 1.4-12.3); GMT=6.3 (95% CI: 5.4-7.4)]. Immune response against the heterologous A/Indonesia/05/2005 strain was also stronger in the H5N1-AS03(A)-groups [seroprotection rate=45.6% (95% CI: 40.0-51.4); GMT=20.5 (95% CI: 17.8-23.7)] compared with the H5N1-DIL groups [seroprotection rate=0.0% (95% CI: 0.0-4.5); GMT=5.0 (95% CI: 5.0-5.0)]. The overall reactogenicity profile of the adjuvanted formulations was clinically acceptable. CONCLUSION: The AS03(A)-adjuvanted H5N1 influenza vaccine formulations induced stronger immune response against the vaccine-homologous and heterologous strains than the nonadjuvanted formulations. The AS03(A)-adjuvanted H5N1 vaccine demonstrated a good immunogenicity and an acceptable safety profile in the Taiwanese population.

A phase II, open-label, multicentre study to evaluate the immunogenicity and safety of an adjuvanted prepandemic (H5N1) influenza vaccine in healthy Japanese adults.

BACKGROUND: Promising clinical data and significant antigen-sparing have been demonstrated for a pandemic H5N1 influenza split-virion vaccine adjuvanted with AS03A, an α-tocopherol-containing oil-in-water emulsion-based Adjuvant System. Although studies using this formulation have been reported, there have been no data for Japanese populations. This study therefore aimed to assess the immunogenicity and tolerability of a prepandemic (H5N1) influenza vaccine adjuvanted with AS03A in Japanese adults. METHODS: This open-label, single-group study was conducted at two centres in Japan in healthy Japanese males and females aged 20-64 years (n = 100). Subjects received two doses of vaccine, containing 3.75 µg haemagglutinin of the A/Indonesia/5/2005-like IBCDC-RG2 Clade 2.1 (H5N1) strain adjuvanted with AS03A, 21 days apart. The primary endpoint evaluated the humoral immune response in terms of H5N1 haemagglutination inhibition (HI) antibody titres against the vaccine strain (Clade 2.1) 21 days after the second dose. Ninety five percent confidence intervals for geometric mean titres, seroprotection, seroconversion and seropositivity rates were calculated. Secondary and exploratory endpoints included the assessment of the humoral response in terms of neutralising antibody titres, the response against additional H5N1 strains (Clade 1 and Clade 2.2), as well as the evaluation of safety and reactogenicity. RESULTS: Robust immune responses were elicited after two doses of the prepandemic influenza vaccine adjuvanted with AS03A. Overall, vaccine HI seroconversion rates and seroprotection rates were 91% 21 days after the second vaccination. This fulfilled all regulatory acceptance criteria for the vaccine-homologous HI antibody level. A substantial cross-reactive humoral immune response was also observed against the virus strains A/turkey/Turkey/1/2005 (Clade 2.2) and A/Vietnam/1194/2004 (Clade 1) after the second vaccine administration. A marked post-vaccination response in terms of neutralising antibody titres was demonstrated and persistence of the immune response was observed 6 months after the first dose. The vaccine was generally well tolerated and there were no serious adverse events reported. CONCLUSIONS: The H5N1 candidate vaccine adjuvanted with AS03A elicited a strong and persistent immune response against the vaccine strain A/Indonesia/5/2005 in Japanese adults. Vaccination with this formulation demonstrated a clinically acceptable reactogenicity profile and did not raise any safety concerns in this population. TRIAL REGISTRATION: Clinicaltrials.gov NCT00742885.

Priming with AS03 A-adjuvanted H5N1 influenza vaccine improves the kinetics, magnitude and durability of the immune response after a heterologous booster vaccination: an open non-randomised extension of a double-blind randomised primary study.

An influenza vaccine with cross-immunogenic potential could play a key role in pandemic mitigation by promoting a rapid immune response to infection and/or subsequent vaccination with strains drifted from the primary vaccine strain. Here we assess the role of AS03(A) (an oil-in-water emulsion based Adjuvant System containing tocopherol) in this prime-boost concept using H5N1 as a model shift influenza antigen. In this open, non-randomised study (NCT00506350; an extension of an earlier randomised study) we assessed immunogenicity in nine groups of 35-50 volunteers aged 19-61 years following administration of AS03(A)-adjuvanted split-virion H5N1 vaccine containing 3.75mug of haemagglutinin (HA) from the A/Indonesia/5/2005(IBCDC-RG2) clade 2.1 strain. A single booster dose of vaccine was administered to four groups primed 14 months previously with different HA levels of AS03(A)-adjuvanted clade 1 A/Vietnam/1194/2004 H5N1 vaccine. Two booster doses (given 21 days apart) were administered to four groups primed 14 months previously with different HA levels of non-adjuvanted A/Vietnam/1194/2004 H5N1 vaccine and also to a control group of un-primed subjects. In individuals primed 14 months earlier with AS03(A)-adjuvanted A/Vietnam/1194/2004 vaccines, a single booster dose of AS03(A)-adjuvanted A/Indonesia/5/2005 induced rapid immune responses (licensure criteria met in 7-14 days) comparable to that observed in the un-primed control group following two doses of adjuvanted vaccine. In contrast, individuals primed with non-adjuvanted formulations exhibited minimal immune responses which, even after two doses, were unexpectedly much lower than that observed in un-primed subjects. AS03(A) enhances the initial priming effect of pandemic influenza vaccination enabling a rapid humoral response to single dose boosting with a heterologous strain at 14 months. In contrast, priming without adjuvant appears to inhibit the response to subsequent vaccination with a heterologous strain. These findings should guide the development of vaccines to combat the present influenza A/H1N1 pandemic.

Immunogenicity and safety in adults of one dose of influenza A H1N1v 2009 vaccine formulated with and without AS03A-adjuvant: preliminary report of an observer-blind, randomised trial.

Governments and public health officials are preparing vaccination campaigns against the 2009 influenza A H1N1v pandemic strain. We evaluated two inactivated split-virion A/California/7/2009 H1N1v pandemic vaccines formulated with/without AS03(A), an oil-in-water emulsion adjuvant system containing tocopherol. This ongoing observer-blind study randomised 130 healthy adults aged 18-60 years to receive either AS03(A)-adjuvanted H1N1 vaccine containing 5.25 microg haemagglutinin (HA) (N=64) or non-adjuvanted H1N1 vaccine containing 21 microg HA (N=66) on Days 0 and 21. We performed a first analysis of reactogenicity and serum haemagglutination-inhibition (HI) antibody responses, 21 days after dose 1. Before vaccination, 12.5% in the AS03(A)-adjuvanted group and 13.1% in the non-adjuvanted group had vaccine-homologous HI titres >or=1:40. Immune responses were robust; HI seroconversion rates were 98.2% and 95.1% and HI seroprotection rates were 98.2% and 98.4%, respectively in the AS03(A) and non-adjuvanted groups. The vaccines were well tolerated with similar adverse event profiles. Solicited injection site and general symptoms were reported more frequently for AS03(A)-adjuvanted vaccine but these were transient and mainly mild to moderate in intensity. Based on accepted immunological surrogates, these preliminary data suggest that one dose of either AS03(A)-adjuvanted H1N1v vaccine at a reduced HA dose or non-adjuvanted H1N1v vaccine at a fourfold higher dose is sufficient to immunise healthy adults. The strong immune response is consistent with prevalent immunological priming but as this and the ability to mount immune response after vaccination may be modulated by age, further investigations in children and in the elderly as well as on the persistence of the immune response are warranted.