A randomized clinical trial to identify the optimal antigen and MF59(®) adjuvant dose of a monovalent A/H1N1 pandemic influenza vaccine in healthy adult and elderly subjects

Analyses of Safety Profile and Homologous Antibody Responses to a Mammalian Cell-Based, MF59-Adjuvanted, A/H5N1, Pandemic Influenza Vaccine across Four Phase II/III Clinical Trials in Healthy Children, Adults, and Older Adults

Modern cell culture-based technology eliminates vaccine manufactures reliance on embryonated chicken eggs, which may become compromised during an avian influenza pandemic. Four studies (total N = 6230) assessed the immunogenicity and safety of mammalian cell-based, MF59^®-adjuvanted, A/H5N1 vaccine (aH5N1c; AUDENZ™) as two doses administered on Days 1 and 22 in children (NCT01776554), adults (NCT01776541; NCT02839330), and older adults (NCT01766921; NCT02839330). Immunogenicity of formulations at 7.5 μg and 3.75 μg antigen per dose were assessed by hemagglutination inhibition and microneutralization assays on Days 1, 22, 43, and 183 or 387. Solicited local and systemic adverse events (AEs) were recorded for 7 days after each vaccination. Unsolicited AEs were collected for 21 days after each vaccination, and serious and other selected AEs were recorded for one year. Antibody responses after two 7.5 μg doses met CBER licensure criteria in all age groups. Overall, an age-related response was evident, with the highest responses observed in children <3 years old. In children, antibody titers met seroconversion criteria 12 months after vaccination. MF59 allowed for antigen dose sparing. Solicited AEs were mild to moderate in nature, of short duration, and less frequent after the second dose than the first, demonstrating a favorable risk-benefit profile.

Next-Generation Influenza HA Immunogens and Adjuvants in Pursuit of a Broadly Protective Vaccine

Influenza virus, a highly mutable respiratory pathogen, causes significant disease nearly every year. Current vaccines are designed to protect against circulating influenza strains of a given season. However, mismatches between vaccine strains and circulating strains, as well as inferior vaccine effectiveness in immunodeficient populations, represent major obstacles. In an effort to expand the breadth of protection elicited by influenza vaccination, one of the major surface glycoproteins, hemagglutinin (HA), has been modified to develop immunogens that display conserved regions from multiple viruses or elicit a highly polyclonal antibody response to broaden protection. These approaches, which target either the head or the stalk domain of HA, or both domains, have shown promise in recent preclinical and clinical studies. Furthermore, the role of adjuvants in bolstering the robustness of the humoral response has been studied, and their effects on the vaccine-elicited antibody repertoire are currently being investigated. This review will discuss the progress made in the universal influenza vaccine field with respect to influenza A viruses from the perspectives of both antigen and adjuvant, with a focus on the elicitation of broadly neutralizing antibodies.

Effectiveness, immunogenicity, and safety of influenza vaccines with MF59 adjuvant in healthy people of different age groups: A systematic review and meta-analysis

BACKGROUND

Influenza is a severe disease burden among all age groups. This study aimed to review the efficacy of inactivated influenza vaccines with MF59 adjuvant and non-adjuvanted inactivated influenza vaccines among all age groups against specific influenza vaccine strains.

METHODS

Literature search of PubMed, Embase, Medline, OVID, and Cochrane Library Trials (CENTRAL) was implemented up to March 1, 2019. Homogeneity qualified studies were included forData were extracted such as study country location, demographic characteristics, and measure outcomes, and were analyzed by a random effect model and sensitivity analyses to identify heterogeneity. Risk of bias was evaluated using the Cochrane Risk of Bias Tool.

RESULTS

We retrieved 1,021 publications and selected 31 studies for full review, including 17 trials for meta-analysis and 6 trials for qualitative synthesis. MF59-adjuvanted influenza vaccines demonstrated better immunogenicity against specific vaccine virus strains compared to non-adjuvanted influenza vaccine both in healthy adult group (RR = 2.10; 95% CI: 1.28-3.44) and the healthy aged (RR = 1.26; 95% CI: 1.10-1.44).

CONCLUSION

The quality of evidence is moderate to high for seroconversion and seroprotection rates of influenza vaccine. MF59-adjuvanted influenza vaccines are superior to non-adjuvanted influenza vaccines to enhance immune responses of vaccination in healthy adults and older adults, and could be considered for routine use especially the monovalent prepandemic influenza vaccines.

An indirect comparison meta-analysis of AS03 and MF59 adjuvants in pandemic influenza A(H1N1)pdm09 vaccines

BACKGROUND

Although oil-in-water adjuvants improve pandemic influenza vaccine efficacy, AS03 versus MF59 adjuvant comparisons in A(H1N1)pdm09 pandemic vaccines are lacking.

METHODS

We conducted an indirect-comparison meta-analysis extracting published data from randomised controlled trials in literature databases (01/01/2009-09/09/2018), evaluating immunogenicity and safety of AS03- or MF59-adjuvanted vaccines. We conducted comparisons of log-transformed haemagglutination inhibition geometric mean titre ratio (GMTR; primary outcome) of different regimens of each adjuvant versus unadjuvanted counterparts. Then via test of subgroup differences, we indirectly compared different AS03 versus MF59 regimens.

RESULTS

We identified 22 publications with 10,734 participants. In adults, AS03-adjuvanted vaccines (3.75 µg haemagglutinin) achieved superior GMTR versus unadjuvanted vaccines (all four comparisons); MD = 0.56 (95%CI 0.33 to 0.80, p < 0.001) to 1.18 (95%CI 0.72 to 1.65, p < 0.001). MF59 (full-dose)-adjuvanted vaccines (7.5 µg haemagglutinin) were superior to unadjuvanted vaccines (three of four comparisons); MD = 0.47 (95%CI 0.19 to 0.75, p = 0.001) to 0.80 (95%CI 0.44 to 1.16, p < 0.001). Adult indirect comparisons favoured AS03 over MF59 (six of eight comparisons; p < 0.001 to p = 0.088). Paediatric indirect comparisons favoured MF59-adjuvanted vaccines (two of seven comparisons; p = 0.011, 0.079). However, unadjuvanted control group seroconversion rate was lower in MF59 than AS03 studies (p < 0.001 to p = 0.097). There was substantial heterogeneity, and adult AS03 studies had lower risk of bias.

CONCLUSIONS

Despite limited studies, in adults, AS03-adjuvanted vaccines allow antigen sparing versus MF59-adjuvanted and unadjuvanted vaccines, with similar immunogenicity, but higher risk of pain and fatigue (secondary outcomes) than unadjuvanted vaccines. In children, adjuvanted vaccines are also superior, but the better adjuvant is uncertain.

Safety and Immunogenicity of MF59-Adjuvanted Cell Culture-Derived A/H5N1 Subunit Influenza Virus Vaccine: Dose-Finding Clinical Trials in Adults and the Elderly

Background

A/H5N1 influenza viruses have high pandemic potential; consequently, vaccines need to be produced rapidly. MF59® adjuvant reduces the antigen required per dose, allowing for dose sparing and more rapid vaccine availability.

Methods

Two multicenter, phase II trials were conducted to evaluate the safety and immunogenicity of an MF59-adjuvanted, cell culture–derived, A/H5N1 vaccine (aH5N1c) among 979 adult (18–64 years old) and 1393 elderly (≥65 years old) subjects. Participants were equally randomized to receive 2 full-dose (7.5 μg of hemagglutinin antigen per dose) or 2 half-dose aH5N1c vaccinations 3 weeks apart. Outcomes were based on Center for Biologics Evaluation Research and Review (CBER) and Committee for Medicinal Products for Human Use (CHMP) licensure criteria (titers ≥1:40 and seroconversions on day 43). Solicited reactions and adverse events were assessed (www.clinicaltrials.gov: NCT01776541 and NCT01766921).

Results

CBER and CHMP criteria were met by both age groups. CBER criteria for hemagglutination titers were met for the full-dose formulation. Solicited reaction frequencies tended to be higher in the full-dose group and were of mild to moderate intensity. No vaccine-related serious adverse events occurred.

Conclusions

In adult and elderly participants, the full-dose aH5N1c vaccine formulation was well tolerated and met US and European licensure criteria for pandemic vaccines.

Immunogenicity of Influenza Vaccines: Evidence for Differential Effect of Secondary Vaccination on Humoral and Cellular Immunity

While currently used influenza vaccines are designed to induce neutralizing antibodies, little is known on T cell responses induced by these vaccines. The 2009 pandemic provided us with the opportunity to evaluate the immune response to vaccination in a unique setting. We evaluated both antibody and T cell responses in a cohort of public health care workers (18–52 years) during two consecutive influenza seasons from 2009 to 2011 and compared the MF59-adjuvanted pandemic vaccine with the unadjuvanted seasonal subunit vaccine that included the pandemic strain [The study was registered in the Netherlands Trial Register (NTR2070)]. Antibody responses were determined in serum by a hemagglutination inhibition assay. Vaccine-specific T cell responses were evaluated by detecting IFN-γ producing peripheral blood mononuclear cells using whole influenza virus or vaccine-specific peptide pools as stimulating antigens. Mixed effects regression models were used to correct the data for influenza-specific pre-existing immunity due to previous infections or vaccinations and for age and sex. We show that one dose of the pandemic vaccine induced antibody responses sufficient for providing seroprotection and that the vaccine induced T cell responses. A second dose further increased antibody responses but not T cell responses. Nonetheless, both could be boosted by the seasonal vaccine in the subsequent season. Furthermore, we show that the seasonal vaccine alone is capable of inducing vaccine-specific T cell responses, despite the fact that the vaccine did not contain an adjuvant. In addition, residual antibody levels remained detectable for over 15 months, while T cell levels in the blood had contracted to baseline levels by that time. Hereby, we show that pandemic as well as seasonal vaccines induce both humoral and cellular responses, however, with a different profile of induction and waning, which has its implications for future vaccine design.

Safety and immunogenicity of inactivated monovalent influenza A/H1N1 vaccine candidate manufactured in Vietnam

We tested a new A/H1N1 inactivated influenza vaccine (IIV) manufactured by Institute of Vaccines and Medical Biologics (IVAC), Vietnam in 48 adults in a Phase 1, double-blinded, randomized, placebo-controlled trial. Two doses of unadjuvanted vaccine or placebo were administered three weeks apart. The vaccine was well tolerated with only transient mild local reactions and low-grade fever in a small proportion of the subjects. One serious adverse event considered unrelated to the study product was reported. The IVAC vaccine proved to be highly immunogenic with 91 percent (95% CI: 0.78, 1) of the subjects developing a ≥4 fold immune responses by hemagglutination inhibition (HAI) assay, and 96 percent (95% CI: 0.78, 1) by the microneutralization (MN) assay. Post-vaccination geometric mean titers (GMTs) were 283.7 (95% CI: 161.7, 497.5) in the HAI and 725.7 (95% CI: 411.3, 1280.3) in the MN assay. These promising results merit further development of the vaccine. ClinicalTrials.gov number: NCT01507779.

Antibody Persistence in Adults Two Years after Vaccination with an H1N1 2009 Pandemic Influenza Virus-Like Particle Vaccine

The influenza virus is a human pathogen that causes epidemics every year, as well as potential pandemic outbreaks, as occurred in 2009. Vaccination has proven to be sufficient in the prevention and containment of viral spreading. In addition to the current egg-based vaccines, new and promising vaccine platforms, such as cell culture-derived vaccines that include virus-like particles (VLPs), have been developed. VLPs have been shown to be both safe and immunogenic against influenza infections. Although antibody persistence has been studied in traditional egg-based influenza vaccines, studies on antibody response durations induced by VLP influenza vaccines in humans are scarce. Here, we show that subjects vaccinated with an insect cell-derived VLP vaccine, in the midst of the 2009 H1N1 influenza pandemic outbreak in Mexico City, showed antibody persistence up to 24 months post-vaccination. Additionally, we found that subjects that reported being revaccinated with a subsequent inactivated influenza virus vaccine showed higher antibody titres to the pandemic influenza virus than those who were not revaccinated. These findings provide insights into the duration of the antibody responses elicited by an insect cell-derived pandemic influenza VLP vaccine and the possible effects of subsequent influenza vaccination on antibody persistence induced by this VLP vaccine in humans.

Cell culture-based influenza vaccines: A necessary and indispensable investment for the future

The traditional platform of using embryonated chicken eggs for the production of influenza vaccines has several drawbacks including the inability to meet the volume of required doses in the case of widespread epidemics and pandemics. Cell culture platforms have therefore been explored in the last 2 decades, and have attracted further attention following the H1N1 pandemic outbreak. This platform, while not the most economical for large-scale production, has several advantages, and can supplement the vaccine requirement when needed. Recent developments in production technologies have contributed greatly to fine-tuning this platform. In combination with other technologies such as live attenuated and recombinant protein or virus-like particle vaccines, and different adjuvants and delivery systems, cell culture-based influenza vaccine platform can be used both for production of seasonal vaccine, and to mitigate vaccine shortages in pandemic situations.

IgG Antibody Responses to Recombinant gp120 Proteins, gp70V1/V2 Scaffolds, and a CyclicV2 Peptide in Thai Phase I/II Vaccine Trials Using Different Vaccine Regimens

RV144 correlates of risk analysis showed that IgG antibodies to gp70V1V2 scaffolds inversely correlated with risk of HIV acquisition. We investigated IgG antibody responses in RV135 and RV132, two ALVAC-HIV prime-boost vaccine trials conducted in Thailand prior to RV144. Both trials used ALVAC-HIV (vCP1521) at 0, 1, 3, and 6 months and HIV-1 gp120MNgD and gp120A244gD in alum (RV135) or gp120SF2 and gp120CM235 in MF59 (RV132) at 3 and 6 months. We assessed ELISA binding antibodies to the envelope proteins (Env) 92TH023, A244gD and MNgD, cyclicV2, and gp70V1V2 CaseA2 (subtype B) and 92TH023 (subtype CRF01_AE), and Env-specific IgG1 and IgG3. Antibody responses to gp120 A244gD, MNgD, and gp70V1V2 92TH023 scaffold were significantly higher in RV135 than in RV132. Antibodies to gp70V1V2 CaseA2 were detected only in RV135 vaccine recipients and IgG1 and IgG3 antibody responses to A244gD were significantly higher in RV135. IgG binding to gp70V1V2 CaseA2 and CRF01_AE scaffolds was higher with the AIDSVAX^®B/E boost but both trials showed similar rates of antibody decline post-vaccination. MF59 did not result in higher IgG antibody responses compared to alum with the antigens tested. However, notable differences in the structure of the recombinant proteins and dosage used for immunizations may have contributed to the magnitude and specificity of IgG induced by the two trials.

A dose-ranging study of MF59(®)-adjuvanted and non-adjuvanted A/H1N1 pandemic influenza vaccine in young to middle-aged and older adult populations to assess safety, immunogenicity, and antibody persistence one year after vaccination

BACKGROUND

During development of an A/H1N1 pandemic influenza vaccine, this study was performed to identify the antigen and adjuvant content which would provide optimal antibody response and persistence in adults and the elderly. Dose-sparing strategies, such as inclusion of adjuvants, are critical in ensuring the widest possible population coverage in the event of an influenza pandemic, despite a limited global capacity for vaccine manufacture.

METHODS

Healthy subjects aged 18-64 years (n = 1240) and ≥65 years (n = 1352) were vaccinated with 1 of 8 investigational vaccine formulations varying in antigen quantity (3.75 µg to 30 µg of hemagglutinin) and MF59(®) adjuvant (none, half dose, or full dose). All subjects received 2 vaccine doses administered 3 weeks apart. Antibody response was assessed by hemagglutination inhibition assay 1 and 3 weeks after administration of first and second doses. Antibody persistence was assessed after 6 and 12 mo. Vaccine safety was monitored over 12 mo.

RESULTS

All 8 investigational A/H1N1 vaccine formulations were well tolerated, and rapidly induced high antibody titers which met all of the Center for Biologics Evaluation and Research (CBER) and Committee for Medicinal Products for Human Use (CHMP) licensure criteria 3 weeks after one dose. The highest antibody titers were observed in participants vaccinated with higher quantities of antigen and adjuvant.

CONCLUSION

A single vaccine dose containing 3.75 µg of A/California/7/2009 (H1N1) antigen with MF59 adjuvant was identified as optimal for young to middle-aged (18-64 years) and older (≥65 years) adult populations.

Safety and Immunogenicity of Cell Culture-Derived A/H3N2 Variant Influenza Vaccines: A Phase I Randomized, Observer-Blind, Dose-Ranging Study

BACKGROUND

A/H3N2 variant (H3N2v) influenza may sustain human-to-human transmission, and an available candidate vaccine would be important.

METHODS

In this phase I, randomized, observer-blind, dose-ranging study, 627 healthy subjects ≥ 3 years of age were randomized to receive 2 vaccinations with H3N2c cell-culture-derived vaccine doses containing 3.75 µg, 7.5 µg, or 15 µg hemagglutinin antigen of H3N2v with or without MF59 (registered trademark of Novartis AG) adjuvant (an oil-in-water emulsion). This paper reports Day 43 planned interim data.

RESULTS

Single MF59-adjuvanted H3N2c doses elicited immune responses in almost all subjects regardless of antigen and adjuvant dose; the Center for Biologics Evaluation Research and Review (CBER) licensure criteria were met for all groups. Subjects with prevaccination hemagglutination inhibition titers <10 and children 3-<9 years achieve CBER criteria only after receiving 2 doses of nonadjuvanted H3N2c vaccine. Highest antibody titers were observed in the 7.5 µg + 0.25 mL MF59 groups in all age cohorts. MF59-adjuvanted H3N2c vaccines showed the highest rates of solicited local and systemic events, predominately mild or moderate.

CONCLUSIONS

A single dose of H3N2c vaccine may be immunogenic and supports further development of MF59-adjuvanted H3N2c vaccines, especially for pediatric populations.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov identifier NCT01855945 (http://clinicaltrials.gov/ct2/show/NCT01855945).

A multi-criteria decision making approach to identify a vaccine formulation

This article illustrates the use of a multi-criteria decision making approach, based on desirability functions, to identify an appropriate adjuvant composition for an influenza vaccine to be used in elderly. The proposed adjuvant system contained two main elements: monophosphoryl lipid and α-tocopherol with squalene in an oil/water emulsion. The objective was to elicit a stronger immune response while maintaining an acceptable reactogenicity and safety profile. The study design, the statistical models, the choice of the desirability functions, the computation of the overall desirability index, and the assessment of the robustness of the ranking are all detailed in this manuscript.

Safety and immunogenicity of an MF59-adjuvanted A/H1N1 pandemic influenza vaccine in children from three to seventeen years of age

OBJECTIVES

This study was designed to identify the optimal dose of an MF59-adjuvanted, monovalent, A/H1N1 influenza vaccine in healthy paediatric subjects.

METHODS

Subjects aged 3-8 years (n=194) and 9-17 years (n=160) were randomized to receive two primary doses of A/H1N1 vaccine containing either 3.75 μg antigen with half a standard dose of MF59 adjuvant, 7.5 μg antigen with a full dose of MF59, or (children 3-8 years only), a non-adjuvanted 15 μg formulation. A booster dose of MF59-adjuvanted seasonal influenza vaccine including homologous A/H1N1 strain was given one year after priming. Immunogenicity was assessed by haemagglutination inhibition (HI) and microneutralization assays. Vaccine safety was assessed throughout the study (up to 18 months).

RESULTS

A single priming dose of either MF59-adjuvanted formulation was sufficient to meet the European licensure criteria for pandemic influenza vaccines (HI titres ≥1:40>70%; seroconversion>40%; and GMR>2.5). Two non-adjuvanted vaccine doses were required to meet the same licensure criteria. After first and second doses, percentage of subjects with HI titres ≥1:40 were between 97% and 100% in the adjuvanted vaccine groups compared with 68% and 91% in the non-adjuvanted group, respectively. Postvaccination seroconversion rates ranged from 91% to 98% in adjuvanted groups and were 68% (first dose) and 98% (second dose) in the non-adjuvanted group. HI titres ≥1:330 after primary doses were achieved in 69% to 90% in adjuvanted groups compared with 41% in the non-adjuvanted group. Long-term antibody persistence after priming and a robust antibody response to booster immunization were observed in all vaccination groups. All A/H1N1 vaccine formulations were generally well tolerated. No vaccine-related serious adverse events occurred, and no subjects were withdrawn from the study due to an adverse event.

CONCLUSIONS

An MF59-adjuvanted influenza vaccine containing 3.75 μg of A/H1N1 antigen was well tolerated and sufficiently immunogenic to meet all the European licensure criteria after a single dose in healthy children 3-17 years old.

Deep phenotyping of the unselected COPSAC2010 birth cohort study

Background

We hypothesize that perinatal exposures, in particular the human microbiome and maternal nutrition during pregnancy, interact with the genetic predisposition to cause an abnormal immune modulation in early life towards a trajectory to chronic inflammatory diseases such as asthma and others.

Objective

The aim of this study is to explore these interactions by conducting a longitudinal study in an unselected cohort of pregnant women and their offspring with emphasis on deep clinical phenotyping, exposure assessment, and biobanking. Exposure assessments focus on the human microbiome. Nutritional intervention during pregnancy in randomized controlled trials are included in the study to prevent disease and to be able to establish causal relationships.

Methods

Pregnant women from eastern Denmark were invited during 2008–2010 to a novel unselected ‘COPSAC₂₀₁₀’ cohort. The women visited the clinic during pregnancy weeks 24 and 36. Their children were followed at the clinic with deep phenotyping and collection of biological samples at nine regular visits until the age of 3 and at acute symptoms. Randomized controlled trials of high‐dose vitamin D and fish oil supplements were conducted during pregnancy, and a trial of azithromycin for acute lung symptoms was conducted in the children with recurrent wheeze.

Results

Seven hundred and thirty‐eight mothers were recruited from week 24 of gestation, and 700 of their children were included in the birth cohort. The cohort has an over‐representation of atopic parents. The participant satisfaction was high and the adherence equally high with 685 children (98%) attending the 1 year clinic visit and 667 children (95%) attending the 2 year clinic visit.

Conclusions

The COPSAC₂₀₁₀ birth cohort study provides longitudinal clinical follow‐up with highly specific end‐points, exposure assessments, and biobanking. The cohort has a high adherence rate promising strong data to elucidate the interaction between genomics and the exposome in perinatal life leading to lifestyle‐related chronic inflammatory disorders such as asthma.

Prospective cohort study of the safety of an influenza A(H1N1) vaccine in pregnant Chinese women

To monitor and evaluate the safety of the influenza A(H1N1) vaccine in pregnant women and its influence on the fetus and neonate, we performed a prospective study in which 122 pregnant Chinese women who received the influenza A(H1N1) vaccine and 104 pregnant women who did not receive any vaccine (serving as controls) were observed. The results indicated that the seroconversion rate in the vaccinated group was 90.4% (95% confidence interval [CI], 82.6% to 95.5%). The rate of adverse events following immunization in the pregnant women who received the influenza A(H1N1) vaccine was 3.3%. The spontaneous abortion rates in the vaccinated group and the unvaccinated group were 0.8% and 1.9%, respectively (exact probability test, P = 0.470), the prolonged-pregnancy rates were 8.2% and 4.8%, respectively (χ(2) = 1.041, P = 0.308), the low-birth-weight rates were 1.6% and 0.95%, respectively (exact probability test, P = 1.000), and the spontaneous-labor rates were 70.5% and 75%, respectively (χ(2) = 0.573, P = 0.449). All newborns who have an Apgar score of ≥7 are considered healthy; Apgar scores of ≥9 were observed in 38.5% and 57.7% of newborns in the vaccinated group and the unvaccinated group, respectively (χ(2) = 8.274, P = 0.004). From these results, we conclude that the influenza A(H1N1) vaccine is safe for pregnant women and has no observed adverse effects on fetal growth. (This study has been registered at ClinicalTrials.gov under registration no. NCT01842997.).

Targeted vaccine selection in influenza vaccination

BACKGROUND

The main target groups for influenza vaccination are the elderly, the chronically ill, infants, and toddlers. Influenza vaccines are needed that suit the immunological particularities of each of these age and risk groups. Recent years have seen the approval of influenza vaccines that are more immunogenic than before, but whose use in Germany is limited by the restriction of reimbursement to a small number of vaccines.

METHODS

The Medline database was selectively searched for pertinent literature.

RESULTS

The suboptimal immunogenicity of conventional influenza vaccines that contain inactivated viral cleavage products and subunits can be markedly improved by the use of squalene-based adjuvant systems, by the integration of viral antigens in virosomal particles, or by intradermal administration. The vaccination of elderly persons with a vaccine containing the adjuvant MF59 was found to lower the risk of hospitalization for influenza or pneumonia by 25% compared to vaccination with a trivalent inactivated vaccine (TIV). On the other hand, the adjuvant ASO3 was found to be associated with an up to 17-fold increase in the frequency of narcolepsy among 4- to 18-year-olds. In a prospective study, a virosomal vaccine lowered the frequency of laboratory-confirmed influenza in vaccinated children by 88% compared to unvaccinated children (2 versus 18 cases per 1000 individuals). A live, attenuated influenza vaccine lowered the rate of disease in children up to age 7 by 48% compared to a TIV (4.2% versus 8.1%).

CONCLUSION

The newer vaccines possess improved efficacy when used for primary and booster immunization in certain age and risk groups, and they are superior in this respect to conventional vaccines based on viral cleavage products and subunits. The risk/benefit profiles of all currently available vaccines vary depending on the age group or risk group in which they are used.

An overview of adjuvant formulations and delivery systems

Adjuvants may promote immune responses: by recruiting professional antigen-presenting cells (APCs) to the vaccination site, increasing the delivery of antigens to APCs, or by activating APCs to produce cytokines and by triggering T cell responses. Aluminium salts have been effective at promoting protective humoral immunity; however, they are not effective in generating cell-mediated immunity. A number of different approaches have been developed to potentiate immune response and they have been partially successful. Research has been conducted into vaccine delivery systems (VDS); enhancing cross-presentation by targeting antigens to (APCs). Antigen discovery has increased over the past decade, and consequently, it has accelerated vaccine development demanding a new generation of VDS that combines different types of adjuvants into specific formulations with greater activity. The new approaches offer a wide spectrum of opportunities in vaccine research with direct applications in the near future.

The history of MF59(®) adjuvant: a phoenix that arose from the ashes

The first clinical trial of an MF59(®)-adjuvanted influenza vaccine (Novartis) was conducted 20 years ago in 1992. The product that emerged (Fluad(®), Novartis) was licensed first in Italy in 1997 and is now licensed worldwide in 30 countries. US licensure is expected in the coming years. By contrast, many alternative adjuvanted vaccines have failed to progress. The key decisions that allowed MF59 to succeed in such a challenging environment are highlighted here and the lessons that were learned along the way are discussed. MF59 was connected to vaccines that did not succeed and was perceived as a 'failure' before it was a success. Importantly, it never failed for safety reasons and was always well tolerated. Even when safety issues have emerged for alternative adjuvants, careful analysis of the substantial safety database for MF59 have shown that there are no significant concerns with widespread use, even in more 'sensitive' populations.

Altered response to A(H1N1)pnd09 vaccination in pregnant women: a single blinded randomized controlled trial

Background

Pregnant women were suspected to be at particular risk when H1N1pnd09 influenza became pandemic in 2009. Our primary objective was to compare the immune responses conferred by MF59®-adjuvanted vaccine (Focetria®) in H1N1pnd09-naïve pregnant and non-pregnant women. The secondary aims were to compare influences of dose and adjuvant on the immune response.

Methods

The study was nested in the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC₂₀₁₀) pregnancy cohort in 2009-2010 and conducted as a single-blinded block-randomised [1∶1∶1] controlled clinical trial in pregnant women after gestational week 20: (1) 7.5 µg H1N1pnd09 antigen with MF59-adjuvant (Pa7.5 µg); (2) 3.75 µg antigen half MF59-adjuvanted (Pa3.75 µg); (3) 15 µg antigen unadjuvanted (P15 µg); and in non-pregnant women receiving (4) 7.5 µg antigen full adjuvanted (NPa7.5 µg). Blood samples were collected at baseline, 3 weeks, 3 and 10 months after vaccination, adverse events were recorded prospectively.

Results

58 pregnant women were allocated to Pa7.5 µg and 149 non-pregnant women were recruited to NPa7.5 µg. The sero-conversion rate was significantly increased in non-pregnant (NPa7.5 µg) compared with pregnant (Pa7.5 µg) women (OR = 2.48 [1.03–5.95], p = 0.04) and geometric mean titers trended towards being higher, but this difference was not statistically significant (ratio 1.27 [0.85–1.93], p = 0.23). The significant titer increase rate showed no difference between pregnant (Pa7.5 µg) and non-pregnant (NPa7.5 µg) groups (OR = 0.49 [0.13–1.85], p = 0.29).

Conclusion

Our study suggests the immune response to the 7.5 µg MF59-adjuvanted Focetria® H1N1pnd09 vaccine in pregnant women may be diminished compared with non-pregnant women.

Trial Registration

ClinicalTrials.gov NCT01012557.