Μg Hemagglutinin Research Articles

Immunogenicity of a half-dose of adjuvanted 2009 pandemic H1N1 influenza vaccine in adults: a prospective cohort study

We aimed to assess the immunogenicity of a single half-dose of AS03-adjuvanted monovalent 2009 pandemic H1N1 vaccine in healthy adults. Healthy subjects age 20-60years were prospectively enrolled in a cohort receiving intramuscular administration of a single half-dose (1.875μg of hemagglutinin [HA]) of adjuvanted 2009 pandemic H1N1 influenza vaccine. Data from participants enrolled in a concomitant study of immunogenicity following a full-dose (3.75μg of HA) are presented concurrently. Sera for assessment of hemagglutination-inhibiting (HAI) antibody to the vaccine strain were obtained before and 14 or 21days after vaccination. Ninety-seven participants received a half-dose and 50 received a full-dose of vaccine. In the half-dose cohort, Food and Drug Administration criteria for immunogenicity regarding seroprotection and seroconversion rates were met for subjects aged 20-45years, but not for those aged 46-60years. There was no statistically significant difference in the proportion of individuals achieving a post-vaccination HAI titre of ≥1:40, the geometric mean titres of post-vaccination antibody, or the proportion of individuals with a four-fold or greater increase in antibody levels between the two cohorts. Participants 46-60years of age were significantly less likely to be seroprotected at day 21 than those 20-45years old in both cohorts. Immunogenicity of a half dose of adjuvanted pH1N1 influenza vaccine was adequate in subjects aged 20-45years. Dose reduction is a possible strategy for expanding the availability in the event of vaccine shortage in this age group.

The mucosal and systemic immune responses elicited by a chitosan‐adjuvanted intranasal influenza H5N1 vaccine

Please cite this paper as: Svindland et al. The mucosal and systemic immune responses elicited by a chitosan‐adjuvanted intranasal influenza H5N1 vaccine. Influenza and Other Respiratory Viruses DOI:10.1111/j.1750‐2659.2011.00271.x. Background Development of influenza vaccines that induce mucosal immunity has been highlighted by the World Health Organisation as a priority (Vaccine 2005;23:1529). Dose‐sparing strategies and an efficient mass‐vaccination regime will be paramount to reduce the morbidity and mortality of a future H5N1 pandemic. Objectives This study has investigated the immune response and the dose‐sparing potential of a chitosan‐adjuvanted intranasal H5N1 (RG‐14) subunit (SU) vaccine in a mouse model. Methods Groups of mice were intranasally immunised once or twice with a chitosan (5 mg/ml)‐adjuvanted SU vaccine [7·5, 15 or 30 μg haemagglutinin (HA)] or with a non‐adjuvanted SU vaccine (30 μg HA). For comparison, another group of mice were intranasally immunised with a whole H5N1 (RG‐14) virus (WV) vaccine (15 μg HA), and the control group consisted of unimmunised mice. Results The chitosan‐adjuvanted SU vaccine induced an immune response superior to that of the non‐adjuvanted SU vaccine. Compared with the non‐adjuvanted SU group, the chitosan‐adjuvanted SU vaccine elicited higher numbers of influenza‐specific antibody‐secreting cells (ASCs), higher concentrations of local and systemic antibodies and correspondingly an improved haemagglutination inhibition (HI) and single radial haemolysis (SRH) response against both the homologous vaccine strain and drifted H5 strains. We measured a mixed T‐helper 1/T‐helper 2 cytokine response in the chitosan‐adjuvanted SU groups, and these groups had an increased percentage of virus‐specific CD4+ T cells producing two Thelper 1 (Th1) cytokines simultaneously compared with the non‐adjuvanted SU group. Overall, the WV vaccine induced higher antibody concentrations in sera and an HI and SRH response similar to that of the chitosan‐adjuvanted SU vaccine. Furthermore, the WV vaccine formulation showed a stronger bias towards a T‐helper 1 profile than the SU vaccine and elicited the highest frequencies of CD4+ Th1 cells simultaneously secreting three different cytokines (INFγ+, IL2+ and INFα+). As expected, two immunisations gave a better immune response than one in all groups. The control group had very low or not detectable results in the performed immunoassays. Conclusion The cross‐clade serum reactivity, improved B‐ and T‐cell responses and dose‐sparing potential of chitosan show that a chitosan‐adjuvanted intranasal influenza vaccine is a promising candidate vaccine for further preclinical development.

Safety and Immunogenicity of a Monovalent 2009 Influenza A/H1N1v Vaccine Adjuvanted With AS03A or Unadjuvanted in HIV-Infected Adults: A Randomized, Controlled Trial

Human immunodeficiency virus (HIV)-infected patients have decreased immune response to vaccines. Few data are available about pandemic flu vaccination in this population. We conducted a multicenter, patient-blinded, randomized trial in a cohort of HIV-infected adults. Patients received 2 injections 21 days apart of a AS03(A)-adjuvanted H1N1v vaccine containing 3.75 μg hemagglutinin (HA) or a nonadjuvanted H1N1v vaccine containing 15 μg HA to assess hemagglutination inhibition (HI) response and safety. A total of 309 patients were randomized, and 306 were vaccinated. After the first vaccine dose, HI titers ≥1:40 were observed in 93.4% of the patients in the adjuvanted group (A group) (n = 155) and in 75.5% in the nonadjuvanted group (B group) (n = 151) (P < .001); seroconversion rates were 88.8% and 71.2%, and factor increases in geometric mean titers (GMT) of 21.9 and 15.1, respectively. After 2 injections, 98.6% of patients of the A group and 92.1% of the B group demonstrated HI titers ≥1:40 (P = .018); seroconversion rates were 96.5% and 87.1%, respectively, and factor increases in GMT were 45.5 and 21.2, respectively. The majority of adverse events were mild to moderate in severity; no impact on CD4+ cell count or viral load has been detected. In HIV-1-infected adults, the AS03(A)-adjuvanted H1N1v vaccine yielded a higher immune response than did the nonadjuvanted one, with no impact on HIV infection.

Downstream processing of Vero cell-derived human influenza A virus (H1N1) grown in serum-free medium

A downstream processing was examined for Vero cell-derived human influenza virus (H1N1) grown in serum free medium. Vero cell banks were established in serum free medium and characterized according to regulatory requirements. Serum free Vero cells were grown on Cytodex 3 microcarriers in 5 L bioreactor and infected with influenza A virus (A/New Caledonia/99/55). The harvests were processed with the sequence of inactivation, clarification, anion exchange chromatography (DEAE FF), Cellufine Sulfate Chromatography (CSC) and size exclusion chromatography (Sepharose 6FF). Host cell DNA (hcDNA) was mainly removed with DEAE FF column and CSC by 40 and 223 fold, respectively. Most of Vero cell proteins were eliminated in CSC and Sepharose 6FF unit operation by about 13 fold. The overall scheme resulted in high recovery of hemagglutinin (HA) activity and the substantial removal of total protein, host protein and DNA. The total protein content and DNA content per 15 μg HA protein in final product was 89 μg and 33 pg, respectively, which complied with regulatory requirements for single strain influenza vaccines. SDS-PAGE analysis and Western blotting confirmed the purity of the final product. In conclusion, the suggested downstream process is suitable for the purification of microcarrier-based cell-derived influenza vaccine.

Dose-Sparing H5N1 A/Indonesia/05/2005 Pre-pandemic Influenza Vaccine in Adults and Elderly Adults: A Phase III, Placebo-Controlled, Randomized Study

Background. Highly pathogenic avian influenza H5N1 viruses remain a threat to human health, with potential to become pandemic agents.Methods. This phase III, placebo-controlled, observer-blinded study evaluated the immunogenicity, cross-reactivity, safety, and lot consistency of 2 doses of oil-in-water (AS03A) adjuvanted H5N1 A/Indonesia/05/2005 (3.75 μg hemagglutinin antigen) prepandemic candidate vaccine in 4561 adults aged 18–91 years.Results. Humoral antibody responses in the H5N1 vaccine groups fulfilled US and European immunogenicity licensure criteria for pandemic vaccines in all age strata 21 days after the second dose. At 6 months after the administration of the primary dose, serum antibody seroconversion rates continued to fulfill licensure criteria. Neutralizing cross-clade immune responses were demonstrated against clade 1 A/Vietnam/1194/2004. Consistency was demonstrated for 3 consecutive H5N1 vaccine lots. Temporary injection-site pain was more frequent with H5N1 vaccine than placebo (89.3% and 70.7% in the 18–64 and ≥65 years strata vs 22.2% and 14.4% in the placebo groups). Unsolicited adverse event frequency, including medically attended and serious events, was similar between groups through day 364.Conclusions. In adults and elderly adults, AS03A-adjuvanted H5N1 candidate vaccine was highly immunogenic for A/Indonesia/05/2005, with cross-reactivity against A/Vietnam/1194/2004. Temporary injection site reactions were more frequent with H5N1 vaccine than placebo, although the H5N1 vaccine was well tolerated overall.Clinical Trials Registration. NCT00616928.

CD4+ T-cell count to predict the response to new H1N1 vaccination in pediatric patients with cancer.

9087 Background: The efficacy of vaccination in (pediatric) cancer patients is still a topic of debate. We aimed to study the immunologic determinants of influenza vaccination response in pediatric cancer patients. Methods: We measured the vaccination response to the new swine-origin influenza A H1N1 in relation to lymphocyte subpopulations in 33 pediatric cancer patients, being treated with chemotherapy or within 6 months after the end of chemotherapy. All patients were vaccinated twice with an intramuscular injection with inactivated split-virion preparation of the A/California/07/2009(H1N1)v like strain (X-179A), which contained 7.5μg of hemagglutinin per dose of 0.5 ml. A protective response was defined as achieving a HI antibody titer ≥ 1:40 following vaccination. Results: From the 33 included patients, 19 (58%) had a protective immune response. We showed a significant relation between response on vaccination and levels of all of the different lymphocyte subpopulations (p<0.001 for the CD4+ T-cells and p=0.001 for total T-cells, CD8+ T-cells and B-cells). Patients with an absolute CD4+ T-cell count less than 200/mm3 did not have a protective vaccination response to new H1N1. Conclusions: Absolute CD4+ T-cell count predicts the response to influenza vaccination in pediatric cancer patients treated with chemotherapy. This finding has important implications for the establishment of a response on vaccination in pediatric cancer patients during treatment with chemotherapy.

Immunological priming induced by a two-dose series of H5N1 influenza antigen, administered alone or in combination with two different formulations of AS03 adjuvant in adults: Results of a randomised single heterologous booster dose study at 15 months

One influenza pandemic preparedness strategy involves priming a population with a pre-pandemic subtype-specific vaccine and boosting the immunological response at the time of the pandemic with a strain-matched vaccine. In the current study, adults (n=469) randomised 15 months previously to receive an A/Indonesia/5/2005 (H5N1) influenza vaccine (3.75μg haemagglutinin antigen [HA]) administered alone or in combination with an oil-in-water emulsion based Adjuvant System containing 11.86mg (AS03A) or 5.93mg (AS03B) tocopherol per dose, received one booster dose of A/turkey/Turkey/1/2005 (H5N1) vaccine (3.75μg HA) with or without AS03A. An anamnestic antibody response that met US regulatory acceptance criteria was observed 15 months after priming. Although superior immunogenicity of AS03-adjuvanted compared to unadjuvanted priming was not demonstrated, higher antibody titres which persisted longer were seen when both priming and boosting regimens were adjuvanted. This may affect duration of response or heterologous immunity. The booster vaccines had a clinically acceptable safety/reactogenicity profile after adjuvanted or unadjuvanted priming. This study has been registered at www.clinicaltrials.govNCT00771615.

Evaluation of Adjuvanted Pandemic H1N12009 Influenza Vaccine After One and Two Doses in Young Children

When Canada chose an adjuvanted influenza A H1N1(2009) vaccine for pandemic control, dosing requirements and safety in children were unknown. This study compared responses after 1 and 2 doses in young children. Five Canadian centers evaluated ASO3-adjuvanted H1N1(2009) vaccine (Arepanrix, GSK Laval, Quebec) in children aged 6 to 35 months, given 2 doses (0.25 mL, 1.9 μg hemagglutinin) 21 days apart. Blood was collected at baseline and 21 to 28 days after each dose to measure hemagglutination inhibition antibody titers. Adverse events were documented daily for 7 days after each dose. Centers enrolled 167 children (mean age, 19 months). At baseline, 29 children (17.4%) had hemagglutination inhibition titers ≥ 10. After dose 1, titers ≥ 40 were present in 79.7% of initially naive subjects and 100% of initially primed subjects, whose respective geometric mean titers were 68 and 1020 (P < 0.001). After dose 2, 100% of subjects had titers ≥ 40, with geometric mean titers increasing to 723 in naive subjects and to 1854 in primed subjects (P < 0.001). Injection site reactions occurred in 56% of subjects after dose 1 and 43% after dose 2 (P < 0.01), with severe reactions noted in ≤ 3%. Fever >39.0°C was infrequent after either dose (5.4%, 6.6%, P = 0.20). Mild or moderate general symptoms were common but short-lived and less frequent after dose 2. One dose of adjuvanted vaccine met criteria for licensing seasonal influenza vaccines. A second dose increased titers substantially, potentially affording greater or more durable protection. Adverse effects were common but tolerable. The use of adjuvanted seasonal influenza vaccines in young children merits consideration.

Immunogenicity and safety of AS03-adjuvanted H1N1 pandemic vaccines in children and adolescents

Vaccines with acceptable efficacy profile against the H1N1 A/California/7/2009 virus are needed for use in children. The two studies presented here evaluated the immunogenicity and the reactogenicity/safety of A/H1N1/2009 vaccines containing either 3.75μg haemagglutinin antigen (HA) and AS03A-adjuvant (3.75μg HA/AS03A study) (N=210 [53, 57 and 100 in the 3–5, 6–9 and 10–17 years age strata, respectively]) or 1.9μg HA and AS03B-adjuvant (1.9μg HA/AS03B study) (N=244 [61, 65 and 118 in the 3–5, 6–9 and 10–17 years age strata, respectively]), given as two-dose series. Although the haemagglutination inhibition antibody titres were higher in the 3.75μg HA/AS03A study, both vaccine dosages were highly immunogenic and exceeded regulatory acceptance criteria after the first and the second doses. Seroprotection rates reached 100% and seroconversion rates ranged from 98.2% to 99.1% after each dose of both vaccine dosages. Geometric mean titres increased from 456.5 to 1538.5 and from 297.9 to 1106.7 between the first and the second doses in the 3.75μg HA/AS03A study and the 1.9μg HA/AS03B study, respectively. Despite an observed slight increase of the reactogenicity following the second dose in the 3.75μg HA/AS03A study, the vaccines safety profiles were considered clinically acceptable. In conclusion, both dosages of the AS03-adjuvanted A/H1N1/2009 pandemic influenza vaccines were highly immunogenic and well-tolerated in children and adolescents.

PCPP-Formulated H5N1 Influenza Vaccine Displays Improved Stability and Dose-Sparing Effect in Lethal Challenge Studies

The potential impact of an influenza pandemic can be mitigated through the realization of a successful vaccination program. The implementation of antigen stabilization and dose-sparing technologies is an important step in improving availability of vaccines at the time of a pandemic outbreak. We investigated poly[di(carboxylatophenoxy)phosphazene] (PCPP) as a potential stabilizing and immunostimulating agent for H5N1 influenza vaccine. Physicochemical characterization of PCPP-formulated H5N1 influenza vaccine revealed macromolecular complexation in the system, whereas single radial immunodiffusion assay verified antigenicity of the formulation in vitro. PCPP-enhanced formulation displayed a fourfold increase in the half-life at 40°C compared with a nonadjuvanted vaccine. Lethal challenge studies in ferrets demonstrated 100% protection for low-antigen dose PCPP-adjuvanted formulations (1 μg of hemagglutinin) and at least a 10-fold antigen-sparing effect. Therefore, PCPP demonstrated an ability to improve thermal stability of H5N1 influenza vaccine in solutions and provide for a substantial dose-sparing effect in vivo.

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.

Influenza virus-like particles as a new tool for vaccine immunogenicity testing: Validation of a neuraminidase neutralizing antibody assay

Detection of neutralizing antibody to viral neuraminidase (NA) by testing for enzyme inhibition has been recognized as an important part of the immunogenicity of influenza vaccines. However, the absence of a well characterized standard source of active NA and validated assays has significantly limited clinical studies of NA immunity. Influenza virus-like particles (VLPs) containing hemagglutinin (HA), NA, and M1 proteins were produced from insect cells infected with a recombinant baculovirus and used as the NA source for the NA inhibition (NAI) assay. The NA activity of 6 different VLP strains varied from 0.43 to 1.61 (×10−3) enzyme units per μg of HA and was stable over 6 months of storage at 2–8°C. The NAI assay using 2′-(4-methylumbelliferyl)-α-d-N-acetylneuraminic acid as a substrate was modified for testing the antibody titer in clinical samples and validated. The advantages of the assay include: (1) stable, reproducible, and standardized source of NA; (2) testing the antibody titer specific to each subtype of NA in serum from subjects immunized with trivalent vaccines (H1N1, H3N2, B) with no interference from antibodies specific to the HA and to heterologous subtypes of the NA; (3) suitability for conducting long-term clinical trials as a result of low intra- and inter-assay variability, and (4) a wide analytical range due to 25% inhibition cut-off value for the NAI titer estimation.

Production of immunogenic one-component avian H7-subtype influenza virus-like particles

Virus-like particles (VLPs) are a highly effective type of subunit vaccines because they mimic the viral capsid without the presence of infectious viral genetic material. In this study, hemagglutinin (HA) alone and in combination with matrix 1 (M1) were highly expressed in Hi-5 insect cells for the production of one-component (containing HA) H-VLP and two-component (containing HA and M1) influenza MH-VLP. The H-VLP or MH-VLP expressed in culture supernatant was purified in fractions with a strong hemagglutination response. Transmission electron microscopy analysis confirmed that the morphology of both H-VLP and MH-VLP was similar to that of authentic influenza virions. After 4 weeks of vaccination, hemagglutination inhibition (HAI) titers induced by either one dose (2μg of HA) or two doses (a dosage of 0.5 or 0.2μg of HA) of both types of VLPs in chickens were all more than 97, well above 16, the predictive protective HAI titer in chickens. These results confirm the effectiveness of insect cell-derived H-VLP and MH-VLP in avian influenza vaccine design. Most importantly, VLPs comprising HA alone provide a simple and fast platform for avian influenza vaccine manufacturing.

Antibody and Th1-type cell-mediated immune responses in elderly and young adults immunized with the standard or a high dose influenza vaccine

A comparative analysis of antibody and cell-mediated immune responses was performed in ambulatory medically stable elderly and young adults who received the standard-dose of trivalent inactivated influenza vaccine, containing 15 μg of hemagglutinin (HA) per virus strain, or a high-dose vaccine containing 60 μg HA per virus strain. Among the elderly, the high dose vaccine induced greater HAI (hemagglutination inhibition) and virus neutralization antibody titers than the standard dose vaccine. These responses, however, did not achieve the magnitude of those induced by the standard dose vaccine in young adults. Vaccine-specific circulating T cells producing IFN-γ were detected in the elderly and young adults following immunization. However, there were no significant differences in the IFN-γ responses among groups. On the other hand, the standard dose vaccine in the elderly resulted in the highest proportion of complete non-responders who failed to elicit either an HAI or an IFN-γ response. This study provides further evidence that a higher dose vaccine for the elderly may result in enhanced immune responses which are predicted to improve protection although still of lower magnitude than those induced in younger healthier individuals.

H5N1 Influenza Vaccine Formulated with AS03A Induces Strong Cross-Reactive and Polyfunctional CD4 T-Cell Responses

ObjectiveAdjuvantation of an H5N1 split-virion influenza vaccine with AS03A substantially reduces the antigen dose required to produce a putatively protective humoral response and promotes cross-clade neutralizing responses. We determined the effect of adjuvantation on antibody persistence and B- and T-cell-mediated immune responses.MethodsTwo vaccinations with a split-virion A/Vietnam/1194/2004 (H5N1, clade 1) vaccine containing 3.75–30 μg hemagglutinin and formulated with or without adjuvant were administered to groups of 50 volunteers aged 18–60 years.ResultsAdjuvantation of the vaccine led to better persistence of neutralizing and hemagglutination-inhibiting antibodies and higher frequencies of antigen-specific memory B cells. Cross-reactive and polyfunctional H5N1-specific CD4 T cells were detected at baseline and were amplified by vaccination. Expansion of CD4 T cells was enhanced by adjuvantation.ConclusionFormulation of the H5N1 vaccine with AS03A enhances antibody persistence and induces stronger T- and B-cell responses. The cross-clade T-cell immunity indicates that the adjuvanted vaccine primes individuals to respond to either infection and/or subsequent vaccination with strains drifted from the primary vaccine strain.

Humoral Response to the Influenza A H1N1/09 Monovalent AS03-Adjuvanted Vaccine in Immunocompromised Patients

Few data are available regarding the immunogenicity and safety of the pandemic influenza vaccine in immunocompromised patients. We evaluated the humoral response to the influenza A H1N1/09 vaccine in solid-organ transplant (SOT) recipients, in patients with human immunodeficiency virus (HIV) infection, and in healthy individuals. Patients scheduled to receive the pandemic influenza vaccine were invited to participate. All participants received the influenza A H1N1/09 AS03-adjuvanted vaccine containing 3.75 μg of hemagglutinin. SOT recipients and HIV-infected patients received 2 doses at 3-week intervals, whereas control subjects received 1 dose. Blood samples were taken at day 0, day 21, and day 49 after vaccination. Antibody responses were measured with the hemagglutination inhibition assay (HIA) and a microneutralization assay. Twenty-nine SOT recipients, 30 HIV-infected patients, and 30 healthy individuals were included in the study. Seroconversion measured by HIA was observed in 15 (52%) of 29 SOT recipients both at day 21 and day 49; in 23 (77%) of 30 at day 21 and 26 (87%) of 30 at day 49 in HIV-infected patients, and in 20 (67%) of 30 at day 21 and in 23 (77%) of 30 at day 49 in control subjects (P = .12 at day 21 and P = .009 at day 49, between groups). Geometric means of antibody titers were not significantly different between groups at day 21 or at day 49. Influenza A H1N1/09 vaccine elicited a similar antibody response in HIV-infected individuals and in control subjects, whereas SOT recipients had an overall lower response. A second dose of the vaccine only moderately improved vaccine immunogenicity in HIV-infected patients.

Intanza®: a new intradermal vaccine for seasonal influenza

Seasonal influenza causes annual epidemics in temperate climates and is associated with economic costs, morbidity and mortality. Vaccination is the primary method of prevention. Intanza® (Sanofi Pasteur, Lyon, France) is a newly licensed, trivalent, inactivated influenza vaccine that is delivered intradermally with a proprietary micoinjection system. Two dosage formulations have been approved for use in Europe and Australia. The dosage level of 9 µg of hemagglutinin per strain is approved for persons 18–59 years of age, and its immunogenicity is noninferior to the standard dosage (15 µg per strain) administered intramuscularly. In addition, the dosage level of 15 µg of hemagglutinin per strain administered intradermally is approved for persons 60 years of age and older and has superior immunogenicity compared with that induced by the same dosage administered intramuscularly. Intanza has more frequent injection-site reactions than intramuscularly delivered vaccine, but it is safe and well tolerated. Intanza provides a new option for the prevention of influenza.

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

BackgroundPromising 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.MethodsThis 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.ResultsRobust 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.ConclusionsThe 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 registrationClinicaltrials.gov NCT00742885

Primary Antibody Responses Against the Novel Pandemic H1N1 and Secondary Antibody Responses Against Seasonal H1N1 Can Be Induced by Vaccination In Patients Early After Allogeneic Stem Cell Transplantation

AbstractAbstract 1273Pandemic influenza (Flu) 2009 and Seasonal Flu are considered a potential health risk for patients after allogeneic stem cell transplantation (alloSCT). However, in a cohort of 137 patients transplanted between October 2006 and December 2009, only 3 patients (2.3%) developed a PCR proven Pandemic Flu infection, and only 1 patient died from multiple super-infections. Moreover, during the Flu season 2009, 5/93 patients (5.3%) transplanted between October 2005 and December 2008 developed a PCR proven Influenza infection and none of them died. These numbers suggest that alloSCT patients were relatively protected against Seasonal and even Pandemic Flu, probably due to earlier Flu antigen exposure. Therefore, we hypothesized that, despite immune impairment after alloSCT, most patients developed secondary and primary antibody responses against Seasonal Flu and neo-antigen containing Pandemic Flu vaccination. To test this hypothesis we measured IgG antibody levels against common Seasonal hemagglutinin (HA), neo-antigens in Pandemic HA and highly conserved cross-reactive re-call antigens shared by Pandemic HA and Seasonal HA in 56 alloSCT patients after vaccination with Seasonal Flu 2009–2010 and Pandemic Flu 2009. To accurately measure antibodies against these antigens, a novel Luminex multiplex bead assay was developed. Recombinant CMV pp65 control protein, native recombinant Seasonal HA (A/Brisbane/59/2007) and Pandemic HA (A/Calefornia/7/2009) were coupled to different Luminex beads which were incubated with plasma samples. To distinguish antibodies against neo-antigenic parts and conserved re-call antigens of Pandemic HA, samples were pre-incubated with or without 0.75 μg HA (A/Brisbane/59/2007) to absorb cross-reacting antibodies against shared parts of Seasonal and Pandemic HA. Finally, samples were stained with PE- labeled Goat α-human IgG and analyzed with a Luminex analyzer. To validate the Luminex bead assay, pp65, Seasonal HA and Pandemic HA positive and negative serum samples were measured with and without pre-incubation with the corresponding protein. In addition, a hemagglutination inhibition assay was performed with Pandemic H1N1 which showed a good correlation with the Luminex assay (r=0.87). Furthermore, specificity of the assay was confirmed by absence of pp65 antibodies in 17 CMV negative patients, whereas in 33/39 (85%) of CMV positive patients antibodies against the immunodominant pp65 protein were detected. To control for vaccination efficacy, 11 healthy donors were vaccinated with Seasonal Flu 2009–2010 followed by 2 Pandemic Flu vaccinations 3 and 6 weeks later. Plasma samples were taken before vaccination, 4 and 12 weeks after Seasonal Flu, and 1 and 8 weeks after Pandemic Flu vaccination. Prior to vaccination all donors had antibodies against Seasonal HA and conserved re-call Pandemic HA, reflecting their previous vaccination with Seasonal Flu 2008–2009. All donors developed secondary antibody responses against Seasonal HA. Highly specific Pandemic HA specific antibodies were present in 1 donor before and 10/11 donors after Pandemic Flu vaccination, indicating that 9/11 donors developed a primary antibody response to neo-antigenic Pandemic HA. To investigate primary and secondary responses after Seasonal and Pandemic Flu vaccination in alloSCT patients, 56 patients followed a similar vaccination and plasma donation scheme. 86% had antibodies against Seasonal HA and 76% against conserved Pandemic HA pre vaccination, probably induced by vaccinations before 2009. 55% developed a secondary antibody response against Seasonal HA 4 –12 weeks post vaccination. Only 5% had neo-antigenic Pandemic HA antibodies prior to vaccination. Excitingly, 57% developed a primary antibody response against neo-antigenic Pandemic HA 8 weeks after Pandemic Flu vaccination. Overall, patients received vaccinations at a median of 443 (range 90–1240) days after alloSCT. Patients vaccinated 90–300, 301–600 and >600 days after alloSCT developed primary antibody responses against neo-antigenic Pandemic HA in 41%, 47% and 80% of the cases, respectively. In conclusion, this detailed analysis of primary and secondary antibody responses against re-call and neo-antigens after Seasonal and 2009 Pandemic HA may explain the low incidence of Flu infections in patients after alloSCT and provides rational arguments to start Flu vaccination from 3 months after alloSCT. Disclosures:No relevant conflicts of interest to declare.

Immunogenicity and safety of influenza A (H1N1) 2009 monovalent inactivated split vaccine in Korea

In a pandemic, the development of an effective influenza vaccine is the most important subject from the view of public health. This study was performed to evaluate the immunogenicity and safety of inactivated, monovalent H1N1 2009 vaccine (Green Cross Corporation, Yongin, Korea) among healthy adults aged 19–64 years (Group 1) and the elderly aged ≥65 years (Group 2) in a two-dose regimen, 21 days apart. At baseline, 28 of 454 participants (6.1%) had hemagglutination-inhibition titers of ≥1:40 with no significant difference between age groups ( p = 0.27). There was an apparent dose-dependent antibody response; participants receiving the dose of 30 μg hemagglutinin (HA) showed higher geometric mean titers (GMTs) than the 15 μg HA group in both age groups. Despite the rates of seroprotection and seroconversion were significantly higher with 30 μg HA formulation than 15 μg HA formula in Group 2, there was no definite difference in Group 1 irrespective of vaccine formula. Significant GMT elevation after the second dose was not noted in either age group, regardless vaccine formulations. No deaths, vaccine-related serious adverse events, or immediate unsolicited adverse reactions occurred during the study periods.