Understanding the impact of adult pertussis and current approaches to vaccination: A narrative review and expert panel recommendations

Pertussis has several notable consequences, causing economic burden, increased strain on healthcare facilities, and reductions in quality of life. Recent years have seen a trend toward an increase in pertussis cases affecting older children and adults. To boost immunity, and protect vulnerable populations, an enduring approach to vaccination has been proposed, but gaps remain in the evidence surrounding adult vaccination that are needed to inform such a policy. Gaps include: the true incidence of pertussis and its complications in adults; regional variations in disease recognition and reporting; and incidence of severe disease, hospitalizations, and deaths in older adults. Better data on the efficacy/effectiveness of pertussis vaccination in adults, duration of protection, and factors leading to poor vaccine uptake are needed. Addressing the critical evidence gaps will help highlight important areas of unmet need and justify the importance of adult pertussis vaccination to healthcare professionals, policymakers, and payers.

Public health management of pertussis in adults: Practical challenges and future strategies

A panel of 24 international experts met in July 2022 to discuss challenges associated with pertussis detection, monitoring, and vaccination in adults; conclusions from this meeting are presented. There has been a shift in the epidemiology of pertussis toward older children and adults. This shift has been attributed to the waning of infection- or vaccine-induced immunity, newer detection techniques causing detection bias, and possibly the replacement of whole-cell pertussis with acellular vaccines in high-income countries, which may lead to immunity waning more quickly. The burden of adult pertussis is still likely under-ascertained due to widespread under-recognition by healthcare professionals (HCPs), under-diagnosis, and under-reporting in this age group. Non-standardized testing guidance and varied case definitions have contributed to under-reporting. Key barriers to HCP engagement with the tetanus, diphtheria, and pertussis (Tdap) vaccine include low awareness, lack of time/funding, and lack of motivation due to low prioritization of Tdap.

4CMenB journey to the 10-year anniversary and beyond

The 4-component meningococcal serogroup B (MenB) vaccine, 4CMenB, the first broadly protective, protein-based MenB vaccine to be licensed, is now registered in more than 50 countries worldwide. Real-world evidence (RWE) from the last decade confirms its effectiveness and impact, with infant immunization programs showing vaccine effectiveness of 71-95% against invasive MenB disease and cross-protection against non-B serogroups, including a 69% decrease in serogroup W cases in 4CMenB-eligible cohorts in England. RWE from different countries also demonstrates the potential for additional moderate protection against gonorrhea in adolescents. The real-world safety profile of 4CMenB is consistent with prelicensure reports. Use of the endogenous complement human serum bactericidal antibody (enc-hSBA) assay against 110 MenB strains may enable assessment of the immunological effectiveness of multicomponent MenB vaccines in clinical trial settings. Equitable access to 4CMenB vaccination is required to better protect all age groups, including older adults, and vulnerable groups through comprehensive immunization policies.

Capturing the Value of Vaccination within Health Technology Assessment and Health Economics-Practical Considerations for Expanding Valuation by Including Key Concepts

Following the development of a value of vaccination (VoV) framework for health technology assessment/cost-effectiveness analysis (HTA/CEA), and identification of three vaccination benefits for near-term inclusion in HTA/CEA, this final paper provides decision makers with methods and examples to consider benefits of health systems strengthening (HSS), equity, and macroeconomic gains. Expert working groups, targeted literature reviews, and case studies were used. Opportunity cost methods were applied for HSS benefits of rotavirus vaccination. Vaccination, with HSS benefits included, reduced the incremental cost-effectiveness ratio (ICER) by 1.4-50.5% (to GBP 11,552-GBP 23,016) depending on alternative conditions considered. Distributional CEA was applied for health equity benefits of meningococcal vaccination. Nearly 80% of prevented cases were among the three most deprived groups. Vaccination, with equity benefits included, reduced the ICER by 22-56% (to GBP 7014-GBP 12,460), depending on equity parameters. Macroeconomic models may inform HTA deliberative processes (e.g., disease impact on the labour force and the wider economy), or macroeconomic outcomes may be assessed for individuals in CEAs (e.g., impact on non-health consumption, leisure time, and income). These case studies show how to assess broader vaccination benefits in current HTA/CEA, providing decision makers with more accurate and complete VoV assessments. More work is needed to refine inputs and methods, especially for macroeconomic gains.

The Platform Technology Approach to mRNA Product Development and Regulation

mRNA-lipid nanoparticle (LNP) medicinal products can be considered a platform technology because the development process is similar for different diseases and conditions, with similar noncoding mRNA sequences and lipid nanoparticles and essentially unchanged manufacturing and analytical methods often utilised for different products. It is critical not to lose the momentum built using the platform approach during the development, regulatory approval and rollout of vaccines for SARS-CoV-2 and its variants. This review proposes a set of modifications to existing regulatory requirements for mRNA products, based on a platform perspective for quality, manufacturing, preclinical, and clinical data. For the first time, we address development and potential regulatory requirements when the mRNA sequences and LNP composition vary in different products as well. In addition, we propose considerations for self-amplifying mRNA, individualised oncology mRNA products, and mRNA therapeutics. Providing a predictable development pathway for academic and commercial groups so that they can know in detail what product characterisation and data are required to develop a dossier for regulatory submission has many potential benefits. These include: reduced development and regulatory costs; faster consumer/patient access and more agile development of products in the face of pandemics; and for rare diseases where alternatives may not exist or to increase survival and the quality of life in cancer patients. Therefore, achieving consensus around platform approaches is both urgent and important. This approach with mRNA can be a template for similar platform frameworks for other therapeutics and vaccines to enable more efficient development and regulatory review.

Broad immunity to SARS-CoV-2 variants of concern mediated by a SARS-CoV-2 receptor-binding domain protein vaccine

BACKGROUND

The SARS-CoV-2 global pandemic has fuelled the generation of vaccines at an unprecedented pace and scale. However, many challenges remain, including: the emergence of vaccine-resistant mutant viruses, vaccine stability during storage and transport, waning vaccine-induced immunity, and concerns about infrequent adverse events associated with existing vaccines.

METHODS

We report on a protein subunit vaccine comprising the receptor-binding domain (RBD) of the ancestral SARS-CoV-2 spike protein, dimerised with an immunoglobulin IgG1 Fc domain. These were tested in conjunction with three different adjuvants: a TLR2 agonist R4-Pam2Cys, an NKT cell agonist glycolipid α-Galactosylceramide, or MF59® squalene oil-in-water adjuvant, using mice, rats and hamsters. We also developed an RBD-human IgG1 Fc vaccine with an RBD sequence of the immuno-evasive beta variant (N501Y, E484K, K417N). These vaccines were also tested as a heterologous third dose booster in mice, following priming with whole spike vaccine.

FINDINGS

Each formulation of the RBD-Fc vaccines drove strong neutralising antibody (nAb) responses and provided durable and highly protective immunity against lower and upper airway infection in mouse models of COVID-19. The 'beta variant' RBD vaccine, combined with MF59® adjuvant, induced strong protection in mice against the beta strain as well as the ancestral strain. Furthermore, when used as a heterologous third dose booster, the RBD-Fc vaccines combined with MF59® increased titres of nAb against other variants including alpha, delta, delta+, gamma, lambda, mu, and omicron BA.1, BA.2 and BA.5.

INTERPRETATION

These results demonstrated that an RBD-Fc protein subunit/MF59® adjuvanted vaccine can induce high levels of broadly reactive nAbs, including when used as a booster following prior immunisation of mice with whole ancestral-strain spike vaccines. This vaccine platform offers a potential approach to augment some of the currently approved vaccines in the face of emerging variants of concern, and it has now entered a phase I clinical trial.

FUNDING

This work was supported by grants from the Medical Research Future Fund (MRFF) (2005846), The Jack Ma Foundation, National Health and Medical Research Council of Australia (NHMRC; 1113293) and Singapore National Medical Research Council (MOH-COVID19RF-003). Individual researchers were supported by an NHMRC Senior Principal Research Fellowship (1117766), NHMRC Investigator Awards (2008913 and 1173871), Australian Research Council Discovery Early Career Research Award (ARC DECRA; DE210100705) and philanthropic awards from IFM investors and the A2 Milk Company.

Identification of an Optimal COVID-19 Booster Allocation Strategy to Minimize Hospital Bed-Days with a Fixed Healthcare Budget

Healthcare decision-makers face difficult decisions regarding COVID-19 booster selection given limited budgets and the need to maximize healthcare gain. A constrained optimization (CO) model was developed to identify booster allocation strategies that minimize bed-days by varying the proportion of the eligible population receiving different boosters, stratified by age, and given limited healthcare expenditure. Three booster options were included: B₁, costing US $1 per dose, B₂, costing US $2, and no booster (NB), costing US $0. B₁ and B₂ were assumed to be 55%/75% effective against mild/moderate COVID-19, respectively, and 90% effective against severe/critical COVID-19. Healthcare expenditure was limited to US$2.10 per person; the minimum expected expense using B_1, B_2, or NB for all. Brazil was the base-case country. The model demonstrated that B₁ for those aged <70 years and B₂ for those ≥70 years were optimal for minimizing bed-days. Compared with NB, bed-days were reduced by 75%, hospital admissions by 68%, and intensive care unit admissions by 90%. Total costs were reduced by 60% with medical resource use reduced by 81%. This illustrates that the CO model can be used by healthcare decision-makers to implement vaccine booster allocation strategies that provide the best healthcare outcomes in a broad range of contexts.

121. Safety, Tolerability, and Pertussis Immunogenicity Findings From a Randomized, Participant-Blinded, Active-Controlled, Dose-Escalating, Phase 1 Trial of a Tetanus/Diphtheria/Pertussis Booster Vaccine (Tdap-1018 CpG Adjuvanted) Compared With Boostrix in Healthy Adults Aged 18 to 22 Years

Background

Bordetella pertussis is a gram-negative bacterium causing the highly contagious respiratory infection pertussis in over 151 000 individuals annually worldwide. A tetanus/diphtheria/pertussis (Tdap) vaccine combined with CpG 1018 adjuvant (Tdap-1018) may induce higher antibody titers than existing aluminum-adjuvanted Tdap vaccines used as a booster in adults.

Methods

In this randomized, active-controlled, participant-blinded, phase 1 trial, healthy adults aged 18 to 22 years received 1 booster injection of Tdap-1018 (with same Tdap composition as in Boostrix and escalating CpG 1018 dose of 1500 µg and 3000 µg) or Boostrix on Day 1. Pertussis immunogenicity evaluations assessed booster response rates (BRRs) for anti-pertussis toxin (anti-PT), anti-filamentous hemagglutinin (anti-FHA), and anti-pertactin (anti-PRN) antibodies, and systems serology at Week 4 post-vaccination. Safety and tolerability were assessed for solicited local and systemic post-injection reactions for 7 days and unsolicited adverse events for 12 weeks after vaccination.

Results

Of the 87 enrolled adult participants, 84 had post-vaccination immunogenicity results. The median age was 19.0 years, 35% were men, and 83% were white. At Week 4, BRRs in the Tdap-1018 3000 µg group were statistically significantly higher (based on lower 95% confidence interval [CI] &gt;0%) than the Boostrix group for anti-PT (difference in BRRs 22.2% [95% CI: 1.5%–42.8%]) and anti-PRN (22.2% [95% CI: 8.2%–40.9%]) antibodies, and similar for anti-FHA (14.8% [95% CI: -2.6%–33.9%]) antibodies (Table). Tdap-1018 1500 µg, Tdap-1018 3000 µg, and Boostrix were generally well tolerated with no observed safety concerns.

Conclusion

In this phase 1 trial, both dose levels of Tdap-1018 were generally well tolerated. Tdap-1018 3000 µg induced statistically significantly higher BRRs than Boostrix for anti-PT and anti-PRN, and a similar response for anti-FHA antibodies.

Disclosures

Robert Janssen, MD, Dynavax Technologies Corporation: employee|Dynavax Technologies Corporation: Stocks/Bonds Tammy Boyce, MEd, Dynavax Technologies Corporation: Employee|Dynavax Technologies Corporation: Stocks/Bonds Fang Xie, PhD, Dynavax Technologies Corporation: Employee|Dynavax Technologies Corporation: Stocks/Bonds Olivier Godeaux, MD, MPH, Dynavax: Advisor/Consultant.

A Complementary Union of SARS-CoV2 Natural and Vaccine Induced Immune Responses

Our understanding of the immune responses that follow SARS-CoV-2 infection and vaccination has progressed considerably since the COVID-19 pandemic was first declared on the 11th of March in 2020. Recovery from infection is associated with the development of protective immune responses, although over time these become less effective against new emerging SARS-CoV-2 variants. Consequently, reinfection with SARS-CoV-2 variants is not infrequent and has contributed to the ongoing pandemic. COVID-19 vaccines have had a tremendous impact on reducing infection and particularly the number of deaths associated with SARS-CoV-2 infection. However, waning of vaccine induced immunity plus the emergence of new variants has necessitated the use of boosters to maintain the benefits of vaccination in reducing COVID-19 associated deaths. Boosting is also beneficial for individuals who have recovered from COVID-19 and developed natural immunity, also enhancing responses immune responses to SARS-CoV-2 variants. This review summarizes our understanding of the immune responses that follow SARS-CoV-2 infection and vaccination, the risks of reinfection with emerging variants and the very important protective role vaccine boosting plays in both vaccinated and previously infected individuals.

Nonhuman primate models for evaluation of SARS-CoV-2 vaccines

INTRODUCTION

Evaluation of immunogenicity and efficacy in animal models provide critical data in vaccine development. Nonhuman primates (NHPs) have been used extensively in the evaluation of SARS-CoV-2 vaccines.

AREAS COVERED

A critical synthesis of SARS-CoV-2 vaccine development with a focus on challenge studies in NHPs is provided. The benefits and drawbacks of the NHP models are discussed. The citations were selected by the authors based on PubMed searches of the literature, summaries from national public health bodies, and press-release information provided by vaccine developers.

EXPERT OPINION

We identify several aspects of NHP models that limit their usefulness for vaccine-challenge studies and numerous variables that constrain comparisons across vaccine platforms. We propose that studies conducted in NHPs for vaccine development should use a standardized protocol and, where possible, be substituted with smaller animal models. This will ensure continued rapid progression of vaccines to clinical trials without compromising assessments of safety or efficacy.

Capturing the value of vaccination within health technology assessment and health economics: Country analysis and priority value concepts

BACKGROUND

A value of vaccination framework for economic evaluation (EE) identified unique value concepts for the broad benefits vaccination provides to individuals, society, healthcare systems and national economies. The objectives of this paper were to work with experts in developed countries to objectively identify three priority concepts to extend current EE.

METHODS

The previously developed classification of value concepts in vaccination distinguished 18 concepts, categorised as conventional payer and societal perspective concepts and novel broader societal concepts. Their inclusion in current EE guidelines was assessed. Experts identified eight criteria relevant to decision-making and measurement feasibility, which were weighted and used to score each concept. The relative ranking of concepts by importance and the gaps in guidelines were used to identify three priority concepts on which to focus immediate efforts to extend EE.

RESULTS

The EE guidelines review highlighted differences across countries and between guidelines and practice. Conventional payer perspective concepts (e.g., individual and societal health gains and medical costs) were generally included, while gaps were evident for conventional societal perspective concepts (e.g., family/caregiver health and economic gains). Few novel broader societal benefits were considered, and only in ad hoc cases. The top-three concepts for near-term consideration: macroeconomic gains (e.g., benefiting the economy, tourism), social equity and ethics (e.g., equal distribution of health outcomes, reduced health/financial equity gaps) and health systems strengthening, resilience and security (e.g., efficiency gains, reduced disruption, increased capacity).

CONCLUSIONS

Gaps, inconsistencies and limited assessment of vaccination value in EE can lead to differences in policy and vaccination access. The three priority concepts identified provide a feasible approach for capturing VoV more broadly in the near-term. Robust methods for measuring and valuing these concepts in future assessments will help strengthen the evidence used to inform decisions, improving access to vaccines that are demonstrably good value for money from society's point of view.

Improving vaccination rates in older adults and at-risk groups: focus on pertussis

Despite the implementation of effective paediatric vaccination programmes, pertussis remains a global health problem. Disease epidemiology has changed over time, shifting towards the adolescent and adult populations. In adults, the true burden of pertussis is greatly underestimated and pertussis vaccine coverage rates are suboptimal, including individuals with chronic conditions. Here, we report the outcomes of a virtual international scientific workshop to assess the evidence on the burden of pertussis in older adults and identify potential solutions to improve uptake of pertussis vaccines. In adults, pertussis is underdiagnosed in part due to atypical or milder clinical presentation and the lack of testing and case confirmation. However, contemporary epidemiological data denoted an increase in the burden of pertussis among adolescents and adults. This might be related to a variety of reasons including the waning of immunity over time, the lack of booster vaccination, and the improved diagnostic methods that led to increased recognition of the disease in adults. Pertussis sequelae can be severe in older adults, particularly those with existing chronic medical conditions, and the vulnerability of these groups is further enhanced by low pertussis vaccine coverage. Possible measures to increase vaccine uptake include strengthening and harmonisation of immunisation guidelines, healthcare professionals taking a more active role in recommending pertussis vaccination, involvement of vaccination centres and pharmacies in the vaccination process, and improving knowledge of pertussis burden and vaccine efficacy among the general population.

The importance of influenza vaccination during the COVID-19 pandemic

The COVID-19 pandemic and the measures taken to mitigate its spread have had a dramatic effect on the circulation patterns of other respiratory viruses, most especially influenza viruses. Since April 2020, the global circulation of influenza has been markedly reduced; however, it is still present in a number of different countries and could pose a renewed threat in the upcoming Northern Hemisphere winter. Influenza vaccination remains the most effective preventive measure that we have at our disposal against influenza infections and should not be ignored for the 2021-2022 season.

A new fully liquid presentation of MenACWY-CRM conjugate vaccine: Results from a multicentre, randomised, controlled, observer-blind study

BACKGROUND

The currently licensed quadrivalent MenACWY-CRM conjugate vaccine presentation consists of two vials (lyophilised MenA and liquid MenCWY) to be reconstituted before injection. A new fully liquid formulation in a single vial has been developed to further improve the vaccine presentation. Since the MenA structure is subject to hydrolytic degradation, this study was conducted to compare the immunogenicity and safety of the investigational MenACWY-CRM liquid vaccine with the licensed vaccine.

METHODS

In this multicentre, randomised, controlled, observer-blind, phase 2b study, 979 healthy adults were administered a single dose of MenACWY-CRM liquid presentation or the currently licensed MenACWY-CRM vaccine. MenA free saccharide generation was accelerated to approximately 30% in the liquid presentation and MenA polysaccharide O-acetylation was reduced to approximately 40%, according to a controlled procedure. Immunological non-inferiority of the MenACWY-CRM liquid to the licensed vaccine, as measured by human serum bactericidal assay (hSBA) geometric mean titres (GMTs) against MenA 1 month post-vaccination, was the primary study objective. Safety assessment was among the secondary objectives.

RESULTS

Immune responses against each serogroup were similar between the two vaccine groups and was non-inferior for MenA. Adjusted hSBA GMTs for MenA were 185.16 and 211.33 for the MenACWY-CRM liquid presentation and currently licensed vaccine presentation, respectively. The between-group ratio of hSBA GMTs for MenA was 0.88, with a two-sided 95% confidence interval lower limit of 0.64, greater than the prespecified non-inferiority margin of 0.5, thus meeting the primary study objective. Both vaccines were well tolerated. No serious adverse events were considered related to vaccination.

CONCLUSIONS

The levels of MenA free saccharide and polysaccharide O-acetylation did not affect the immunogenicity of the fully liquid presentation, which was demonstrated to be non-inferior to the immunogenicity of the currently licensed MenACWY-CRM vaccine against MenA. The immunogenicity, reactogenicity and safety profiles of the two vaccine presentations were similar.

National predictors of influenza vaccine uptake in pregnancy: the FluMum prospective cohort study, Australia, 2012-2015

OBJECTIVE

Ascertain predictors of inactivated influenza vaccine (IIV) uptake in pregnancy in mother-infant pairs from six Australian sites over four consecutive influenza seasons (2012-2015).

METHODS

Prospective observational cohort study calculating proportions of unvaccinated and vaccinated pregnancies. Multivariable logistic regression calculating adjusted odds ratios (aOR) and 95% confidence intervals (95%CI) to determine demographic, pregnancy and birth characteristics as predictors of IIV uptake in pregnancy.

RESULTS

Uptake of IIV was 36% (n=3,651/9,878) with only 3-4% during the first trimester. Validation of IIV receipt was obtained for 77% of vaccinated participants. Predictors of IIV uptake in pregnancy were: healthcare provider recommendation to have IIV during pregnancy (aOR 7.04 [95%CI 5.83-8.50]): GP (aOR 4.12 [95%CI 3.43-4.98]), obstetrician (aOR 4.41 [95%CI 3.45-5.64]), midwife (aOR 1.88 [95%CI 1.51-2.36]); previous IIV within 12 months of their current pregnancy (aOR 2.87 [95%CI 2.36-3.50]); and pertussis vaccination during the current pregnancy (aOR 4.88 [95%CI 4.08-5.83]). Conclusions and implications for public health: Healthcare provider discussions with pregnant women about the risks associated with influenza infection during pregnancy and early infancy and evidence about the safety and effectiveness of IIV are required. Recommending and offering IIV in pregnancy needs to be included in these discussions to improve uptake.

Control of vaccine preventable diseases in Australian infants: reviewing a decade of experience with DTPa-HBV-IPV/Hib vaccine

The combined vaccine against diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, and Haemophilus influenzae b (DTPa-HBV-IPV/Hib, Infanrix Hexa, GSK) has been used for childhood immunization in Australia according to a two-, four-, six-month schedule since 2009. We reviewed data available in the Australian National Notifiable Diseases Surveillance System, annual vaccination coverage reports, the Database of Adverse Event Notifications, and peer-reviewed literature to assess vaccine coverage rates, incidence of all six vaccine preventable diseases, and the safety profile of DTPa-HBV-IPV/Hib vaccine in Australian infants over a period of ten years of exclusive use. Between 2009 and 2018 vaccine coverage for infants aged 12 months increased from 91.7% to 94.0% and from 84.9% to 92.6% for all and for Indigenous infants, respectively. Over the same time period, there were no reports of poliomyelitis, diphtheria or tetanus in infants <12 months of age. The incidence of hepatitis B among Australian infants <12 months of age remains 10 to 20-fold lower than the national average. Control of Haemophilus influenzae b (Hib) and pertussis disease has continued to be challenging. Timely administration of the primary series, as well as increasing coverage rates, particularly among Indigenous children, has contributed to improvements in Hib and pertussis disease control. The incorporation of additional strategies such as adjustment of the first vaccination encounter to six weeks of age, parental cocooning, and most recently maternal vaccination has further reduced the burden of pertussis, particularly during the first six months of life. The frequency of the ten most common adverse events related to the DTPa-HBV-IPV/Hib vaccine demonstrates an acceptable safety profile. Data collected over ten years of consistent, exclusive use of the DTPa-HBV-IPV/Hib vaccine in Australia highlights combination vaccination as a cornerstone in maintaining infant health.

The Safety of Influenza and Pertussis Vaccination in Pregnancy in a Cohort of Australian Mother-Infant Pairs, 2012-2015: The FluMum Study

Background

Inactivated influenza vaccine (IIV) and pertussis vaccination are recommended in pregnancy. Limited safety data exist for women who received IIV vaccine during the first trimester of pregnancy or received both vaccines in pregnancy. We assessed adverse birth outcomes between vaccinated and unvaccinated pregnancies.

Methods

Among prospectively enrolled Australian "FluMum" participants (2012-2015), primary exposure was receipt and timing of IIV during pregnancy. Primary outcomes included preterm birth, low birthweight at term (LBWT), and small for gestational age (SGA). We compared birth outcomes for IIV in pregnancy with women unvaccinated in pregnancy using Cox proportional hazard ratios (HRs) with 95% confidence intervals (CIs). Adjusted HRs (aHRs) controlled for potential confounding variables. Sensitivity analyses were conducted in a subgroup of women who received pertussis vaccination during pregnancy to assess whether associations between IIV and adverse outcomes were maintained after adjusting for pertussis vaccination.

Results

Among 8827 participants in our study, women who received IIV in pregnancy did not have an elevated risk of an adverse birth outcome compared with unvaccinated pregnant women: preterm births (HR, 1.10 [95% CI, .92-1.31]; P = .28); LBWT (HR, 1.05 [95% CI, .76-1.44]; P = .77); or SGA (HR, 0.99 [95% CI, .86-1.15]; P = .94). Adjustment for pertussis vaccination during pregnancy yielded similar results: preterm births (aHR, 1.05 [95% CI, .82-1.34]; P = .69); LBWT (aHR, 0.81 [95% CI, .50-1.29]; P = .37); SGA (aHR, 0.92 [95% CI, .74-1.14]; P = .43). There was no evidence of elevated risk by trimester of IIV.

Conclusions

No significant associations were found between maternal IIV or pertussis vaccination in pregnancy and adverse birth outcomes, regardless of the trimester of pregnancy a vaccination was given compared to unvaccinated pregnancies.

Impact of tetanus-diphtheria-acellular pertussis immunization during pregnancy on subsequent infant immunization seroresponses: follow-up from a large randomized placebo-controlled trial

BACKGROUND

Pertussis immunization during pregnancy results in high pertussis antibody concentrations in young infants but may interfere with infant immune responses to post-natal immunization.

METHODS

This phase IV, multi-country, open-label study assessed the immunogenicity and safety of infant primary vaccination with DTaP-HepB-IPV/Hib and 13-valent pneumococcal conjugate vaccine (PCV13). Enrolled infants (6-14 weeks old) were born to mothers who were randomized to receive reduced-antigen-content diphtheria-tetanus-three-component acellular pertussis vaccine (Tdap group) or placebo (control group) during pregnancy (27^0/7-36^6/7 weeks' gestation) with crossover immunization postpartum. All infants received 2 or 3 DTaP-HepB-IPV/Hib and PCV13 doses according to national schedules. Immunogenicity was assessed in infants pre- and 1 month post-primary vaccination. The primary objective was to assess seroprotection/vaccine response rates for DTaP-HepB-IPV/Hib antigens 1 month post-primary vaccination.

RESULTS

601 infants (Tdap group: 296; control group: 305) were vaccinated. One month post-priming, seroprotection rates were 100% (diphtheria; tetanus), ≥98.5% (hepatitis B), ≥95.9% (polio) and ≥94.5% (Hib) in both groups. Vaccine response rates for pertussis antigens were significantly lower in infants whose mothers received pregnancy Tdap (37.5-77.1%) versus placebo (90.0-99.2%). Solicited and unsolicited adverse event rates were similar between groups. Serious adverse events occurred in 2.4% (Tdap group) and 5.6% (control group) of infants, none were vaccination-related.

CONCLUSIONS

Pertussis antibodies transferred during pregnancy may decrease the risk of pertussis infection in the first months of life but interfere with the infant's ability to produce pertussis antibodies, the clinical significance of which remains unknown. Safety and reactogenicity results were consistent with previous experience.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02422264.

Persistence of the immune response after 4CMenB vaccination, and the response to an additional booster dose in infants, children, adolescents, and young adults

The multicomponent meningococcal serogroup B vaccine, 4CMenB, has demonstrated effectiveness in preventing invasive MenB disease in infants and in controlling MenB outbreaks. The need for/timing of additional booster doses is not yet established. We reviewed eight studies that evaluated antibody persistence and booster following primary 4CMenB vaccination of infants, children, adolescents, and young adults. Putative seroprotective hSBA titers for ≥1 vaccine antigen were maintained by 76-100% of children 24-36 months after priming during infancy and in 84-100% after priming in the second year of life. hSBA levels were higher in vaccinees at 4 and 7.5 years following priming during adolescence than in vaccine-naïve individuals of a similar age. Antibodies persisted at higher levels to NHBA and NadA than to PorA or fHbp. Booster vaccination induced robust anamnestic responses, demonstrating effective priming by 4CMenB across age-groups. These data can inform decision-making to optimize vaccination strategies.

Immunogenicity and Safety of a Quadrivalent Meningococcal ACWY-tetanus Toxoid Conjugate Vaccine 6 Years After MenC Priming as Toddlers

BACKGROUND

We assessed immunogenicity, antibody persistence and safety of the meningococcal serogroups A, C, W and Y-tetanus toxoid (TT) conjugate vaccine (MenACWY-TT) in children primed as toddlers with MenC vaccine.

METHODS

This open, multicenter extension study enrolled children 84-95 months of age who had received one dose of the combined Haemophilus influenzae type b (Hib)-MenC-TT conjugate vaccine (HibMenC group) or Hib-TT and monovalent MenC (MCC)-CRM197 vaccines (Hib+MCC group) at 12-18 months of age, in the primary study. All participants received one dose of MenACWY-TT. We assessed immunogenicity against MenA, MenC, MenW and MenY at 1 month and 2 years postvaccination by serum bactericidal assay using baby rabbit complement (rSBA). Safety and reactogenicity were evaluated.

RESULTS

Six years post-MenC vaccination, <20% of children retained rSBA-MenC titers ≥1:8. At 1 month post-MenACWY-TT vaccination, vaccine response rates against all serogroups were high for both groups with ≥97.1% of children having rSBA ≥1:8. Two years postvaccination, ≥63.6% of children retained rSBA-MenA ≥1:8, and ≥87.9% for other serogroups. Geometric mean titers for all serogroups declined at 2 years post-MenACWY-TT vaccination, but remained ≥13 times higher than prevaccination levels. For both groups, pain (≤58.5%), redness (≤51.4%) and fatigue (≤27.0%) were the most frequently reported adverse events. No serious adverse events were reported.

CONCLUSIONS

One dose of MenACWY-TT boosts protection against MenC in primed children, is safe and extends protection against MenA, MenW and MenY. Immunogenicity and safety were comparable in infants vaccinated with conjugated vaccine (HibMenC-TT) or the separate vaccines (Hib-TT and MCC-CRM197).