Waning protection following 5 doses of a 3-component diphtheria,tetanus, and acellular pertussis vaccine

BackgroundThe effectiveness of diphtheria, tetanus, and acellular pertussis (DTaP) vaccines wanes substantially after the 5^th dose given at ages 4–6 years, but has not been described following 5 doses of the same type of DTaP vaccine. We investigated waning effectiveness against pertussis in California over nearly 10 years, which included large pertussis outbreaks, following 5 doses of GSK DTaP vaccines (DTaP₃).MethodsWe conducted a case-control study (NCT02447978) of children who received 5 doses of DTaP at Kaiser Permanente Northern California from 01/2006 through 03/2015. We compared time since the 5^th dose in confirmed pertussis polymerase chain reaction (PCR)-positive cases with pertussis PCR-negative controls. We used logistic regression adjusted for calendar time, age, sex, race, and service area to estimate the effect of time since the 5^th DTaP dose on the odds of pertussis. Our primary analysis evaluated waning after 5 doses of DTaP₃. We also examined waning after 5 doses of any type of DTaP vaccines.ResultsOur primary analysis compared 340 pertussis cases diagnosed at ages 4–12 years with 3841 controls. The any DTaP analysis compared 462 pertussis cases with 5649 controls. The majority of all DTaP doses in the study population were DTaP₃ (86.8%). Children who were more remote from their 5^th dose were less protected than were children whose 5^th dose was more recent; the adjusted odds of pertussis increased by 1.27 per year (95% CI 1.10, 1.46) after 5 doses of DTaP₃ and by 1.30 per year (95% CI 1.15, 1.46) after any 5 DTaP vaccines doses.ConclusionsWaning protection after DTaP₃ was similar to that following 5 doses of any type of DTaP vaccines. This finding is not unexpected as most of the DTaP vaccines administered were DTaP_3. Following 5 doses of DTaP₃ vaccines, protection from pertussis waned 27% per year on average.NCT number: NCT02447978.     

Patient attitudes toward influenza and tetanus,diphtheria and acellular pertussis vaccination in pregnancy

BackgroundRoutine influenza and tetanus, diphtheria and acellular pertussis (Tdap) vaccination of pregnant women to prevent poor maternal, fetal and neonatal outcomes is recommended practice; however, actual rates of influenza vaccine acceptance are typically well below the (Healthy People 2020, 2015) goal of 80%.ObjectiveWe sought to identify barriers to accepting either vaccination.Materials and MethodsFrom December 2014 to April 2015 women were given a questionnaire eliciting their experiences, attitudes and history of influenza and Tdap vaccination in pregnancy during their routine prenatal care appointments at a tertiary care center. Patient demographics were included in the questionnaire. A similar questionnaire was administered to prenatal care providers. Patient influenza and Tdap vaccination acceptance rates were compared and predictors of vaccine acceptance were analyzed with bivariate logistic regression.ResultsOut of the 400 patient questionnaires distributed, 338 (84.5%) were completed and returned; 24 of 45 (53.3%) provider questionnaires were returned. Vaccination acceptance rates were 70.7% for the influenza vaccine and 76.3% for the Tdap vaccine. The logistic regression model indicated that predictors of acceptance for either vaccine in pregnancy are patient attitude and previous vaccination history. Patient attitudes were more favorable towards Tdap than influenza vaccination. The combination of healthcare provider recommendation and educational materials was significantly predictive of both Tdap and influenza vaccine acceptance. The most common reasons given for declining the influenza vaccine were safety concerns; the most common reasons given for declining the Tdap vaccine were that patients did not think it was required again when they received the vaccine before pregnancy.ConclusionsOur study suggests that providers can improve Tdap and influenza vaccination acceptance in pregnancy by recommending the vaccination in combination with provision of educational materials on the vaccines.     

Immunogenicity and safety of the quadrivalent meningococcal vaccine MenACWY-TT co-administered with a combined diphtheria-tetanus-acellular pertussis vaccine versus their separate administration in adolescents and young adults: A phase III,randomized study

BackgroundThis study evaluated the immunogenicity and safety of quadrivalent meningococcal conjugate vaccine using tetanus (T) toxoid as carrier protein (MenACWY-TT) co-administered with combined diphtheria-tetanus-acellular pertussis vaccine (Tdap) versus their separate administration in adolescents and young adults.MethodsIn this phase III, randomized, partially-blind study (NCT01767376), healthy 11–25-year-olds (N = 660) were randomized (1:1:1) to receive MenACWY-TT and Tdap at Month 0 (Co-ad group), MenACWY-TT at Month 0 and Tdap at Month 1 (ACWY_Tdap group) or Tdap at Month 0 and MenACWY-TT at Month 1 (Tdap_ACWY group). Immune responses to MenACWY-TT were measured by serum bactericidal assay using rabbit complement (rSBA). Anti-diphtheria (D), anti-tetanus (T), anti-pertussis toxin (PT), anti-filamentous hemagglutinin (FHA) and anti-pertactin (PRN) antibody concentrations were assessed using enzyme-linked immunosorbent assays. Non-inferiority of immunogenicity was assessed using pre-defined clinical criteria. Safety was also evaluated.ResultsNon-inferiority of immunogenicity of MenACWY-TT and Tdap when co-administered versus their separate administration was demonstrated in terms of rSBA geometric mean titers (GMTs) for 4 meningococcal serogroups and of the percentage of participants with antibody concentrations >1 IU/ml for D and T. Among the pertussis antigens, non-inferiority criteria for geometric mean concentrations (GMCs) were reached for PT, but not met for FHA and PRN. Across all groups, ≥93.2% of participants had vaccine responses to each meningococcal serogroup, ≥99.1% were seroprotected against T and D, and ≥85.5% had booster responses to each pertussis antigen. Robust increases in antibody GMTs/GMCs were observed for all antigens between pre-and post-vaccination. Both vaccines had clinically acceptable safety profiles.ConclusionImmune responses to MenACWY-TT and to the T and D antigens from Tdap were not impacted by their co-administration. The lower antibody concentrations observed against the pertussis components may be of limited clinical relevance since robust anti-pertussis booster responses were observed. This study supports concurrent administration of the 2 vaccines in adolescents.     

Effectiveness of acellular pertussis vaccine in a routine immunization program: A multicenter,case-control study in Japan

In 2008, the number of pertussis cases increased substantially among Japanese adolescents, despite high coverage with acellular pertussis vaccine (DTaP). This study examined the effectiveness of DTaP vaccine in the routine immunization program in Japan. Between April 2009 and October 2012, we conducted a multicenter, case-control study, and compared the history of DTaP vaccination between 55 newly diagnosed pertussis cases and 90 age- and sex-matched controls. DTaP vaccine history was obtained by a self-administered questionnaire completed by their parents or guardians. Logistic regression models were used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) of vaccination for development of pertussis.DTaP vaccination of ≥1 dose revealed a significantly lower OR for pertussis (OR = 0.20, 95%CI, 0.04–0.97), and the OR of complete vaccination (4 doses) was 0.22 (0.04–1.05). Even after limiting subjects to those whose vaccination status could be confirmed by the immunization records, the negative associations were observed. The decreasing ORs of 4-dose vaccinees remained, even among subjects who had received the fourth dose ≥9.2 years earlier (OR = 0.11, 95%CI, 0.01–1.02).In conclusion, DTaP vaccination had a preventive effect for pertussis. Effectiveness was observed even 9 or more years after the final dose.     

Multiplex immunoassay for in vitro characterization of acellular pertussis antigens in combination vaccines

Vaccines characterization is required to ensure physical, chemical, and biological integrity of antigens and adjuvants. Current analytical methods mostly require complete antigen desorption from aluminum-based adjuvants and are not always suitable to distinguish individual antigens in multivalent formulations. Here, Luminex technology is proposed to improve the analytics of vaccine characterization. As proof of concept, TdaP (tetanus, diphtheria and acellular pertussis) combination, adjuvanted with aluminum hydroxide, was chosen as model formulation to quantify and determine the level of adsorption of acellular pertussis (aP) antigens onto adjuvant surface at the same time. The assay used specific antibodies bound to magnetic microspheres presenting unique digital signatures for each pertussis antigen, allowing the simultaneous recognition of respective antigens in the whole vaccine, avoiding laborious procedures for adjuvant separation. Accurate and reproducible quantification of aP antigens in TdaP vaccine has been achieved in the range 0.78–50 ng/mL, providing simultaneously information on antigen identity, quantity, and degree of adsorption to aluminum hydroxide. The current study could further be considered as a model to set up in vitro potency assays thus supporting the replacement of animal tests accordingly to the 3Rs concept.     

Tetanus,diphtheria, and acellular pertussis vaccination during pregnancy and reduced risk of infant acute respiratory infections

BackgroundTo protect infants from pertussis infection, the Advisory Committee on Immunization Practices (ACIP) recommends women receive the tetanus toxoid, reduced diphtheria toxoid, acellular pertussis (Tdap) vaccine between 27 and 36 weeks of pregnancy. Here, we assessed the association between timing of maternal Tdap vaccination during pregnancy and acute respiratory infection (ARI) in infants <2 months of age.MethodsThis retrospective cohort study included 99,434 infants born to active duty military women in the Department of Defense Birth and Infant Health Registry from 2006 through 2013. Multivariable log-binomial regression was used to calculate relative risks (RRs) and 95% confidence intervals (CIs) for the association between maternal Tdap vaccination during pregnancy and infant ARI at <2 months of age.ResultsInfants of mothers who received Tdap vaccination during pregnancy vs those who did not were 9% less likely to be diagnosed with an ARI at <2 months of age (RR, 0.91; 95% CI, 0.84–0.99), and the risk was 17% lower if vaccination was received between 27 and 36 weeks of pregnancy (RR, 0.83; 95% CI, 0.74–0.93). Similar results were observed when comparing mothers who received Tdap vaccination prior to pregnancy in addition to Tdap vaccination between 27 and 36 weeks of pregnancy versus mothers who only received vaccination prior to pregnancy (RR, 0.85; 95% CI, 0.74–0.98).ConclusionsMaternal Tdap vaccination between 27 and 36 weeks of pregnancy was consistently protective against infant ARI in the first 2 months of life vs no vaccination during pregnancy, regardless of Tdap vaccination prior to pregnancy. Our findings strongly support current ACIP guidelines recommending Tdap vaccination in late pregnancy for every pregnancy.     

Combined tetanus-diphtheria and pertussis vaccine during pregnancy: transfer of maternal pertussis antibodies to the newborn

Background and objectivesPertussis is currently an emerging public health concern in some countries with high vaccination coverage. It is expected that maternal pertussis immunization could provide newborn protection. We compared pertussis toxin antibody (anti-PT) levels in women during pregnancy (pre- and post-vaccination) with respect to levels in the newborn at delivery in women vaccinated during pregnancy. We also estimated anti-PT titers at primary infant vaccination.MethodsObservational study of pregnant women vaccinated with Tdap (≥20 weeks gestation) and their newborns between May 2012 and August 2013. Anti-PT levels were determined by ELISA in maternal (pre- and post-vaccination) and newborn blood.ResultsPre-vaccination, post-vaccination maternal and newborn samples were available in 132 subjects. Mean maternal age was 34.2 (SD 4.3) years. Median weeks of gestation at vaccination were 27.2 (Q1–Q3 21.7–30.8). Anti-PT (≥10 IU/ml) levels were found in 37.1% of maternal pre-vaccination samples (geometric mean titer (GMT) 7.9 IU/ml (95% CI 6.8–9.2)), 90.2% of post-vaccination samples (GMT 31.1 IU/ml (95% CI 26.6–36.3)) and 94.7% of newborns (GMT 37.8 IU/ml (95% CI 32.3–44.1)). The Lin concordance index between post-vaccination maternal and newborn samples was 0.8 (95% CI 0.8–0.9). Transplacental transfer ratio was 146.6%. At two months of age, 66% of newborns had estimated anti-PT levels ≥10 IU/ml.ConclusionsThere was a high correlation between anti-PT levels in mothers and newborns, with higher levels in newborns, which should be sufficient to provide protection against pertussis during the first months of life. Vaccination of pregnant women seems to be an immunogenic strategy to protect newborns until primary infant immunization.     

Antibody persistence and safety and immunogenicity of a second booster dose nine years after a first booster vaccination with a reduced antigen diphtheria-tetanus-acellular pertussis vaccine (Tdap) in adults

BackgroundOver the last decades, pertussis showed periodic increases in its incidence among adults, despite being a vaccine-preventable disease.MethodsThis phase III, multicenter, extension study (NCT00489970) was conducted in adults from the United States, followed at Year (Y) 5 and Y9 post-vaccination with a dose of reduced-antigen-content tetanus-diphtheria-acellular pertussis vaccine containing either 3 (Tdap-B group) or 5 pertussis components (Tdap-A group). Willing participants in Tdap groups and newly-recruited participants (Control group) received one Tdap-B dose at Y9. Antibody persistence (at Y5 and Y9) and safety of Tdap-B at Y9 were assessed. Non-inferiority of immune response elicited by 2 Tdap doses was evaluated at Y9: (i) versus one Tdap-B dose for diphtheria and tetanus in terms of seroprotection rates; (ii) for all antigens in terms of booster response rates (Tdap-B and Tdap-A groups versus Control group); and (iii) for pertussis antigens in terms of geometric mean concentrations (GMCs) versus a 3-dose series of a combined diphtheria-tetanus-acellular pertussis vaccine (DTPa) administered during infancy.Results1257 participants were enrolled at Y5 and 809 participants were vaccinated at Y9. Seroprotection rates in both Tdap groups were ≥98.4% and ≥98.0% (Y5) and ≥98.3% and ≥98.1% (Y9) for diphtheria and tetanus, respectively. For pertussis antigens, antibody concentrations above assay cut-offs were observed for ≥76.6% (Y5) and ≥84.9% (Y9) of participants in Tdap groups. At Y9, one month post-Tdap vaccination, comparable seroprotection/seropositivity rates and antibody GMCs were observed among groups. Non-inferiority of immune responses in both Tdap groups was demonstrated when compared to the Control group for diphtheria and tetanus and to a 3-dose DTPa series for pertussis antigens. Non-inferiority criteria in terms of booster response were not met for all antigens. No safety concerns were raised.ConclusionA second dose of Tdap-B administered in adults, 9 years after initial Tdap vaccination, is immunogenic and well-tolerated.     

Modulation of the CD4+ T cell response after acellular pertussis vaccination in the presence of TLR4 ligation

Whole cell pertussis (wP) vaccines are gradually being replaced by aluminum salt-adjuvanted acellular pertussis (aP) vaccines. These promote CD4⁺ T cell responses with a non-protective Th2 component, while protective immune mechanisms to B. pertussis may rather involve long-lived Th1/Th17 type CD4⁺ T cells. Here we asked whether addition of a non-toxic meningococcal LPS derivative, LpxL1, as adjuvant can favorably modulate the aP-induced pertussis-specific CD4⁺ T cell response in mice. To assess the effect of TLR4 ligation, Th type, quantity, and memory potential of pertussis-specific CD4⁺ T cells were determined at the single-cell level after aP and aP+LpxL1 vaccination using intracellular cytokine staining and MHC class II tetramers. Adding LpxL1 to the aP vaccine weakened the Th2 component and strengthened the Th1/Th17 component of the specific CD4⁺ T cell response. Notably, LpxL1 addition also induced higher frequencies of tetramer positive CD4⁺ T cells in draining lymph nodes or blood, depending on the phase after vaccination. Moreover, there was a net profit in the number of CD4⁺ T cells with a central memory phenotype, preferred for long-term immunity. Thus, adding a TLR4 ligand as adjuvant to a current aP vaccine was associated with a more favorable pertussis-specific CD4⁺ T cell response.     

Immunogenicity and safety of a quadrivalent inactivated influenza vaccine compared with two trivalent inactivated influenza vaccines containing alternate B strains in adults: A phase 3, randomized noninferiority study

BackgroundVaccination is the most effective means of influenza prevention. Efficacy of trivalent vaccines may be enhanced by including both B strain lineages. This phase 3, double-blind study assessed the immunogenicity and safety/tolerability of a quadrivalent inactivated influenza vaccine (IIV4) versus the United States (US)-licensed 2014–2015 trivalent inactivated influenza vaccine (IIV3-Yamagata [IIV3-YAM]; Afluria) and IIV3 containing the alternate Victoria B strain (IIV3-VIC) in adults ≥18 years.MethodsParticipants (n = 3484) were randomized 2:1:1 and stratified by age to receive IIV4 (n = 1741), IIV3-YAM (n = 871), or IIV3-VIC (n = 872). The primary objective was to demonstrate noninferiority of the immunological response to IIV4 versus IIV3-YAM and IIV3-VIC. Noninferiority was assessed by hemagglutination inhibition geometric mean titer (GMT) ratio (IIV3/IIV4; upper bound of two-sided 95% confidence interval [CI] ≤ 1.5) and seroconversion rate (SCR) difference (IIV3 – IIV4; upper bound of two-sided 95% CI ≤ 10%) for vaccine strains. Solicited local and systemic adverse events (AEs) were assessed for 7 days postvaccination, AEs recorded for 28 days postvaccination, and serious AEs for 6 months postvaccination.ResultsIIV4 elicited a noninferior immune response for matched strains, and superior response for unmatched B strains not contained in IIV3 comparators. Adjusted GMT ratios (95% CI) for A/H1N1, A/H3N2, B/YAM, and B/VIC strains were 0.93 (0.88, 0.99), 0.93 (0.88, 0.98), 0.87 (IIV3-YAM; 0.82, 0.93), and 0.95 (IIV3-VIC; 0.88, 1.03), respectively. Corresponding values for SCR differences (95% CI) were −1.1 (−4.5, 2.3), −1.7 (−5.0, 1.7), −3.2 (IIV3-YAM; −7.4, 0.9), and −1.6 (IIV3-VIC; −5.8, 2.5). AEs were generally mild and experienced by 52.9% of participants. Serious AEs were reported with a slightly higher frequency with IIV4 (2.3%) versus IIV3-YAM (1.6%) and IIV3-VIC (1.5%).ConclusionsIIV4 demonstrated immunological noninferiority to the US-licensed IIV3, and superiority for unmatched B strains not contained in IIV3 comparators. Safety/tolerability profiles were similar across vaccine groups.Funding: Seqirus; Clinicaltrials.gov: NCT02214225.     

Safety and immunogenicity of a quadrivalent intradermal influenza vaccine in adults

BackgroundAn intradermal (ID) trivalent split-virion influenza vaccine (IIV3-ID) (Fluzone^® Intradermal, Sanofi Pasteur, Swiftwater, PA) has been available in the US since the 2011/2012 influenza season for adults aged 18–64 years. This study examined whether adding a second B-lineage strain affects immunogenicity and safety.MethodsThis randomized, double-blind, multicentre trial evaluated the immunogenicity and safety of an intradermal quadrivalent split-virion influenza vaccine (IIV4-ID) in adults 18–64 years of age in the US during the 2012–2013 influenza season. Participants were randomized 2:1:1 to receive a single injection of IIV4-ID, licensed IIV3-ID, or an investigational IIV3-ID containing the alternate B-lineage strain. Haemagglutination inhibition antibody titres were assessed in two-thirds of participants before vaccination and 28 days after vaccination.Results1672 participants were vaccinated with IIV4-ID, 837 with licensed IIV3-ID, and 846 with an investigational IIV3-ID. For all four vaccine strains, antibody responses to IIV4-ID were statistically non-inferior to the response to the IIV3-ID vaccines containing the matched strains. For both B strains, post-vaccination antibody responses to IIV4-ID were statistically superior to the responses to IIV3-ID lacking the corresponding B strain. Adverse events were similar for IIV4-ID and IIV3-ID. The most commonly reported solicited reactions were pain, pruritus, myalgia, headache, and malaise; and most were grade 1 or 2 and appeared and resolved within 3 days of vaccination. IIV4-ID was statistically non-inferior to the two pooled IIV3-ID vaccines for the proportions of participants with at least one grade 2 or 3 systemic reaction.ConclusionsAntibody responses to the IIV4-ID were non-inferior to IIV3-ID for the A and matched B strains and superior for the unmatched B strains. IIV4-ID was well tolerated without any safety concerns. IIV4-ID may help address an unmet need due to mismatched B strains in previous influenza vaccines.     

Safety and immunogenicity of a trivalent recombinant PcpA,PhtD, and PlyD1 pneumococcal protein vaccine in adults,toddlers, and infants: A phase I randomized controlled study

BackgroundPneumococcal protein vaccines (PPrVs) may provide improved protection over currently available polysaccharide and conjugated polysaccharide vaccines. Here, we examined the safety and immunogenicity of a trivalent recombinant PPrV containing PcpA, PhtD, and PlyD1.MethodsThis was a phase I, single-center, randomized, observer-blind study with safety review between cohorts. Adults (18–50 years; n = 30) and then toddlers (12–13 months; n = 30) were randomized 2:1 to receive aluminum-adjuvanted trivalent PPrV (PPrV + adj) containing 50 μg per antigen or placebo. Infants (42–49 days; n = 220) were next randomized to be injected at 6, 10, and 14 weeks of age with 10 μg PPrV + adj or placebo (n = 60; 2:1); 25 μg PPrV + adj, 25 μg unadjuvanted PPrV, or placebo (n = 100; 2:2:1); and 50 μg PPrV + adj or placebo (n = 60; 2:1). Solicited reactions were recorded for 7 days and unsolicited adverse events for 30 days after each vaccination. Concentrations of antibodies to the three vaccine antigens were measured by enzyme-linked immunosorbent assay.ResultsTenderness/pain was the most frequent injection-site reaction. Abnormal crying and irritability (infants), loss of appetite (toddlers), and headache, malaise, and myalgia (adults) were the most frequent systemic reactions. Reactions were mostly mild or moderate, resolved within 3 days, were not adjuvant- or dose-dependent, and were not increased by repeated vaccination. No immediate adverse events, hypersensitivity reactions, or treatment-related serious adverse events were reported. In all PPrV + adj cohorts, at least 75% of subjects had a ≥2-fold increase in all three antibody concentrations. In infants, antibody concentrations were higher with PPrV + adj than with unadjuvanted PPrV, higher with three than two vaccinations, and similar at the different vaccine doses.ConclusionsThe candidate trivalent PPrV was safe and immunogenic in adults, toddlers, and infants. Addition of aluminum adjuvant improved immunogenicity in infants without changing the safety profile.     

Effect of jet injection on infectivity of measles,mumps, and rubella vaccine in a bench model

Disposable-syringe jet injectors (DSJIs) with single-use, auto disable, needle-free syringes offer the opportunity to avoid hazards associated with injection using a needle and syringe. Clinical studies have evaluated DSJIs for vaccine delivery, but most studies have focused on inactivated, subunit, or DNA vaccines. Questions have been raised about possible damage to live attenuated viral vaccines by forces generated during the jet injection process. This study examines the effect of jet injection on the integrity of measles, mumps, and rubella vaccine (MMR), measured by viral RNA content and infectivity. Three models of DSJIs were evaluated, each generating a different ejection force. Following jet injection, the RNA content for each of the vaccine components was measured using RT-qPCR immediately after injection and following passage in Vero cells. Jet injection was performed with and without pig skin as a simulation of human skin. There was little to no reduction of RNA content immediately following jet injection with any of the three DSJIs. Samples passaged in Vero cells showed no loss in infectivity of the measles vaccine following jet injection. Mumps vaccine consistently showed increased replication following jet injection. Rubella vaccine showed no loss after jet injection alone but some infectivity loss following injection through pig skin with two of the devices. Overall, these data demonstrated that forces exerted on a live attenuated MMR vaccine did not compromise vaccine infectivity. The bench model and protocol used in this study can be applied to evaluate the impact of jet injection on other live virus vaccines.     

Immunogenicity and safety of the new intradermal influenza vaccine in adults and elderly: A randomized phase 1/2 clinical trial

BackgroundRecent clinical evidence indicates that an intradermal (ID) delivery of vaccines confers superior immunogenicity as compared to a standard intramusclular or subcutaneous (SC) delivery.MethodsIn this exploratory study, 600 healthy adults were randomized to 6 study groups with subgroups of young adults (20–64 years old) and older adults (65 years and older). The subjects were either injected by a novel ID injection system with a single dose of 6, 9, or 15 μg HA or two doses (21 days apart) of 15 μg HA per strain or injected by an SC injection method with a single or two doses (21 days apart) of 15 μg HA per strain. Immunogenicity was assessed using hemagglutination inhibition (HAI) titer and microneutralization titer on Days 0, 10, 21, and 42. Solicited and unsolicited adverse events were recorded for 7 and 21 days post-vaccination, respectively.ResultsIn both young adults and older adults groups, the geometric titer (GMT) ratios of HAI in the ID 15 μg HA group were higher than those in the SC 15 μg HA group on both Day 10 and Day 21, while those in the ID 6 and ID 9 μg HA groups were comparable with those in the SC 15 μg HA group. The kinetics of GMTs of HAI suggested that the ID vaccine has the potential to induce the prompt immune response, which is rather hampered in older adults as seen in the SC vaccine groups. The injection-site AEs were generally mild and transient, and did not occur in a dose or dosage-dependent manner.ConclusionsThe results of this study clearly suggest that the immunologic profile of the ID vaccine is better than that of the SC vaccine, while the safety profile of the ID vaccine is similar to that of the SC vaccine. In this exploratory study with almost 100 subjects per each group, single or two-dose administration of the ID vaccine containing 15 μg HA was suggested to be an appropriate regimen in order to prevent influenza and to reduce the associated disease burden.Trial registrationJAPIC Clinical Trials Information (JapicCTI-132096).     

Waning vaccine protection against influenza A (H3N2) illness in children and older adults during a single season

BackgroundRecent studies have suggested that vaccine-induced protection against influenza may decline within one season. We reanalyzed data from a study of influenza vaccine effectiveness to determine if time since vaccination was an independent predictor of influenza A (H3N2).MethodsPatients with acute respiratory illness were actively recruited during the 2007–2008 season. Respiratory swabs were tested for influenza, and vaccination dates were determined by a validated immunization registry. The association between influenza RT-PCR result and vaccination interval (days) was examined using multivariable logistic regression, adjusting for calendar time, age and other confounders.ResultsThere were 629 vaccinated participants, including 177 influenza A (H3N2) cases and 452 test negative controls. The mean (SD) interval from vaccination to illness onset was 101.7 (25.9) days for influenza cases and 93.0 (29.9) days for controls. There was a significant association between vaccination interval and influenza result in the main effects model. The adjusted odds ratio (aOR) for influenza was 1.12 (CI 1.01, 1.26) for every 14 day increase in the vaccination interval. Age modified the association between vaccination interval and influenza (p = 0.005 for interaction). Influenza was associated with increasing vaccination interval in young children and older adults, but not in adolescents or non-elderly adults. Similar results were found when calendar week of vaccine receipt was assessed as the primary exposure variable.ConclusionsIdentification of influenza A (H3N2) was associated with increasing time since vaccination among young children and older adults during a single influenza season.     

A phase 1 study of safety and immunogenicity following intradermal administration of a tetravalent dengue vaccine candidate

BackgroundAs part of the ongoing search for an effective dengue vaccine, Takeda performed a phase 1b study to investigate the safety and immunogenicity of an early low-dose tetravalent dengue vaccine candidate formulation (LD-TDV), based on an attenuated serotype 2 backbone, when administered intradermally with an injector device (PharmaJet®), or needle-syringe.MethodsThe study was performed in two centers in the US, in healthy 18–45 year old subjects with no history of dengue vaccination or disease. One or two vaccine doses were given on Day 0, and another dose or placebo on Day 90. Neutralizing antibodies were measured up to Day 270; safety was assessed as laboratory measurements and solicited and unsolicited adverse events on diary cards.ResultsChanges in World Health Organization prequalification guidance for new vaccines concerning storage conditions favored the use of lyophilized preparations, and led to the early cessation of enrolment, but not before 67 subjects were enrolled in four treatment groups. Sixty-five subjects completed the planned schedule. There were no safety signals or serious adverse events. All vaccination regimens elicited neutralizing antibodies. Titers of neutralizing antibodies against serotypes 1 and 2 were higher than those against serotypes 3 and 4. There were no consistent increases in responses with two doses given either concomitantly or 90 days apart.ConclusionsSimultaneous injection of two LD-TDV doses was shown to have the potential to improve seroconversion rates to serotypes 1 and 2, and to increase serotype 2 antibody titers. A primary dose of LD-TDV administered by PharmaJet was shown to induce more rapid seroconversion to serotypes 1, 2, and 3 compared with administration by needle-syringe (ClinicalTrials.gov: NCT01765426).     

Modeling the long-term antibody response of a hepatitis E vaccine

BackgroundThe first commercialized hepatitis E vaccine, HEV 239, has been shown to be safe and highly immunogenic, the protection as well as the vaccine-induced anti-HEV maintained for at least 4.5 years. However, the longer term persistence of the vaccine-induced anti-HEV responses is unknown.MethodsTwo statistical models, the power-law model and the modified power-law model, were applied to predict the long-term antibody response of the HEV 239 vaccine. The models were fit using the anti-HEV IgG data from a modeling subpopulation of 1278 baseline seronegative vaccinees who seroconverted within one month after finishing the whole vaccination course in the phase 3 trial of HEV 239. In addition, antibody data from a validation subpopulation were used to validate the robustness of the derived models.ResultsIn the vaccinees without pre-vaccination immunity, the power-law model and the modified power-law model estimated that the median duration of the detectable antibody (≥0.077 WU/ml) was 8 years and 13 years, respectively. The power-law model and the modified power-law model estimated that 50% of these vaccinees will maintain detectable levels of anti-HEV IgG for 8 years and >30 years, respectively.ConclusionsThe recombinant hepatitis E vaccine HEV 239 is predicted to provide from 8 years to nearly life-long persistence of anti-HEV IgG above detectable levels. Model predictions are based on conservative mathematical assumptions.(NCT01014845).     

Immunogenicity and safety of an AS03-adjuvanted H5N1 pandemic influenza vaccine in Korean adults: A phase IV,randomized, open-label,controlled study

BackgroundAS03-adjuvanted H5N1 pandemic influenza vaccines have been assessed in an extensive clinical development program conducted in North America, Europe, and Asia including children from 6 months of age, adults, and elderly adults. We evaluated AS03-H5N1 in Korean adults 18 through 60 years of age.MethodsThis Phase IV, randomized, study was conducted to assess the immunogenicity, reactogenicity, and safety of two doses (3.75 μg of hemagglutinin antigen) of A/Indonesia/5/2005 (H5N1) adjuvanted with AS03 given 21 days apart in Korean adults. Antibody responses were assessed using hemagglutination-inhibition (HI) assays against the vaccine strain and a vaccine-heterologous strain (A/Vietnam/1194/2004) 21 days after the second dose. A control group (safety) received a licensed seasonal inactivated trivalent influenza vaccine (TIV). Reactogenicity was assessed for 7 days after each vaccination, and unsolicited adverse events were assessed for 182 days following vaccination in both study groups (NCT01730378).ResultsAS03-H5N1 was immunogenic and elicited robust HI antibody responses with seroconversion rates of 100% for the vaccine strain and 69.1% for the heterologous strain (N = 81). HI antibody responses fulfilled the European licensure criteria for immunogenicity (primary endpoint). The incidence of local and systemic solicited adverse events (reactogenicity) was higher with AS03-H5N1 than TIV. There was no apparent difference in the rate of unsolicited adverse events in the AS03-H5N1 and TIV groups.ConclusionThe results indicate that AS03-H5N1 vaccine is immunogenic with reactogenicity and safety findings that are consistent with the established profile of AS03-H5N1 vaccine.     

A recombinant varicella vaccine harboring a respiratory syncytial virus gene induces humoral immunity

The varicella-zoster virus (VZV) Oka vaccine strain (vOka) is highly efficient and causes few adverse events; therefore, it is used worldwide. We previously constructed recombinant vOka (rvOka) harboring the mumps virus gene. Immunizing guinea pigs with rvOka induced the production of neutralizing antibodies against the mumps virus and VZV.Here, we constructed recombinant vOka viruses containing either the respiratory syncytial virus (RSV) subgroup A fusion glycoprotein (RSV A–F) gene or RSV subgroup B fusion glycoprotein (RSV B–F) gene (rvOka-RSV A–F or rvOka-RSV B–F). Indirect immunofluorescence and Western blot analyses confirmed the expression of each recombinant RSV protein in virus-infected cells. Immunizing guinea pigs with rvOka-RSV A–F or rvOka-RSV B–F led to the induction of antibodies against RSV proteins. These results suggest that the current varicella vaccine genome can be used to generate custom-made vaccine vectors to develop the next generation of live vaccines.