Immune responses to pertussis vaccines and disease

Immunogenicity, reactogenicity, and IgE-mediated immune responses of a mixed whole-cell and acellular pertussis vaccine schedule in Australian infants: A randomised, double-blind, noninferiority trial

BACKGROUND

In many countries, infant vaccination with acellular pertussis (aP) vaccines has replaced use of more reactogenic whole-cell pertussis (wP) vaccines. Based on immunological and epidemiological evidence, we hypothesised that substituting the first aP dose in the routine vaccination schedule with wP vaccine might protect against IgE-mediated food allergy. We aimed to compare reactogenicity, immunogenicity, and IgE-mediated responses of a mixed wP/aP primary schedule versus the standard aP-only schedule.

METHODS AND FINDINGS

OPTIMUM is a Bayesian, 2-stage, double-blind, randomised trial. In stage one, infants were assigned (1:1) to either a first dose of a pentavalent wP combination vaccine (DTwP-Hib-HepB, Pentabio PT Bio Farma, Indonesia) or a hexavalent aP vaccine (DTaP-Hib-HepB-IPV, Infanrix hexa, GlaxoSmithKline, Australia) at approximately 6 weeks old. Subsequently, all infants received the hexavalent aP vaccine at 4 and 6 months old as well as an aP vaccine at 18 months old (DTaP-IPV, Infanrix-IPV, GlaxoSmithKline, Australia). Stage two is ongoing and follows the above randomisation strategy and vaccination schedule. Ahead of ascertainment of the primary clinical outcome of allergist-confirmed IgE-mediated food allergy by 12 months old, here we present the results of secondary immunogenicity, reactogenicity, tetanus toxoid IgE-mediated immune responses, and parental acceptability endpoints. Serum IgG responses to diphtheria, tetanus, and pertussis antigens were measured using a multiplex fluorescent bead-based immunoassay; total and specific IgE were measured in plasma by means of the ImmunoCAP assay (Thermo Fisher Scientific). The immunogenicity of the mixed schedule was defined as being noninferior to that of the aP-only schedule using a noninferiority margin of 2/3 on the ratio of the geometric mean concentrations (GMR) of pertussis toxin (PT)-IgG 1 month after the 6-month aP. Solicited adverse reactions were summarised by study arm and included all children who received the first dose of either wP or aP. Parental acceptance was assessed using a 5-point Likert scale. The primary analyses were based on intention-to-treat (ITT); secondary per-protocol (PP) analyses were also performed. The trial is registered with ANZCTR (ACTRN12617000065392p). Between March 7, 2018 and January 13, 2020, 150 infants were randomised (75 per arm). PT-IgG responses of the mixed schedule were noninferior to the aP-only schedule at approximately 1 month after the 6-month aP dose [GMR = 0·98, 95% credible interval (0·77 to 1·26); probability (GMR > 2/3) > 0·99; ITT analysis]. At 7 months old, the posterior median probability of quantitation for tetanus toxoid IgE was 0·22 (95% credible interval 0·12 to 0·34) in both the mixed schedule group and in the aP-only group. Despite exclusions, the results were consistent in the PP analysis. At 6 weeks old, irritability was the most common systemic solicited reaction reported in wP (65 [88%] of 74) versus aP (59 [82%] of 72) vaccinees. At the same age, severe systemic reactions were reported among 14 (19%) of 74 infants after wP and 8 (11%) of 72 infants after aP. There were 7 SAEs among 5 participants within the first 6 months of follow-up; on blinded assessment, none were deemed to be related to the study vaccines. Parental acceptance of mixed and aP-only schedules was high (71 [97%] of 73 versus 69 [96%] of 72 would agree to have the same schedule again).

CONCLUSIONS

Compared to the aP-only schedule, the mixed schedule evoked noninferior PT-IgG responses, was associated with more severe reactions, but was well accepted by parents. Tetanus toxoid IgE responses did not differ across the study groups.

TRIAL REGISTRATION

Trial registered at the Australian and New Zealand Clinical 207 Trial Registry (ACTRN12617000065392p).

Antibody and B-cell Immune Responses Against Bordetella Pertussis Following Infection and Immunization

Neither immunization nor recovery from natural infection provides life-long protection against Bordetella pertussis. Replacement of a whole-cell pertussis (wP) vaccine with an acellular pertussis (aP) vaccine, mutations in B. pertussis strains, and better diagnostic techniques, contribute to resurgence of number of cases especially in young infants. Development of new immunization strategies relies on a comprehensive understanding of immune system responses to infection and immunization and how triggering these immune components would ensure protective immunity. In this review, we assess how B cells, and their secretory products, antibodies, respond to B. pertussis infection, current and novel vaccines and highlight similarities and differences in these responses. We first focus on antibody-mediated immunity. We discuss antibody (sub)classes, elaborate on antibody avidity, ability to neutralize pertussis toxin, and summarize different effector functions, i.e. ability to activate complement, promote phagocytosis and activate NK cells. We then discuss challenges and opportunities in studying B-cell immunity. We highlight shared and unique aspects of B-cell and plasma cell responses to infection and immunization, and discuss how responses to novel immunization strategies better resemble those triggered by a natural infection (i.e., by triggering responses in mucosa and production of IgA). With this comprehensive review, we aim to shed some new light on the role of B cells and antibodies in the pertussis immunity to guide new vaccine development.

Immunomodulation of Antibody Glycosylation through the Placental Transfer

Establishing an immune balance between the mother and fetus during gestation is crucial, with the placenta acting as the epicenter of immune tolerance. The placental transfer of antibodies, mainly immunoglobulin G (IgG), is critical in protecting the developing fetus from infections. This review looks at how immunomodulation of antibody glycosylation occurs during placental transfer and how it affects fetal health. The passage of maternal IgG antibodies through the placental layers, including the syncytiotrophoblast, stroma, and fetal endothelium, is discussed. The effect of IgG subclass, glycosylation, concentration, maternal infections, and antigen specificity on antibody transfer efficiency is investigated. FcRn-mediated IgG transport, influenced by pH-dependent binding, is essential for placental transfer. Additionally, this review delves into the impact of glycosylation patterns on antibody functionality, considering both protective and pathological effects. Factors affecting the transfer of protective antibodies, such as maternal vaccination, are discussed along with reducing harmful antibodies. This in-depth examination of placental antibody transfer and glycosylation provides insights into improving neonatal immunity and mitigating the effects of maternal autoimmune and alloimmune conditions.

Coping Strategies for Pertussis Resurgence

Pertussis (whooping cough) is a respiratory disease caused primarily by Bordetella pertussis, a Gram-negative bacteria. Pertussis is a relatively contagious infectious disease in people of all ages, mainly affecting newborns and infants under 2 months of age. Pertussis is undergoing a resurgence despite decades of high rates of vaccination. To better cope with the challenge of pertussis resurgence, we evaluated its possible causes and potential countermeasures in the narrative review. Expanded vaccination coverage, optimized vaccination strategies, and the development of a new pertussis vaccine may contribute to the control of pertussis.

Development of carbohydrate based next-generation anti-pertussis vaccines

Pertussis is a highly contagious respiratory disease caused by the Gram-negative bacterial pathogen, Bordetella pertussis. Despite high global vaccination rates, pertussis is resurging worldwide. Here we discuss the development of current pertussis vaccines and their limitations, which highlight the need for new vaccines that can protect against the disease and prevent development of the carrier state, thereby reducing transmission. The lipo-oligosaccharide of Bp is an attractive antigen for vaccine development as the anti-glycan antibodies could have bactericidal activities. The structure of the lipo-oligosaccharide has been determined and its immunological properties analyzed. Strategies enabling the expression, isolation, and bioconjugation have been presented. However, obtaining the saccharide on a large scale with high purity remains one of the main obstacles. Chemical synthesis provides a complementary approach to accessing the carbohydrate epitopes in a pure and structurally well-defined form. The first total synthesis of the non-reducing end pertussis pentasaccharide is discussed. The conjugate of the synthetic glycan with a powerful immunogenic carrier, bacteriophage Qβ, results in high levels and long-lasting anti-glycan IgG antibodies, paving the way for the development of a new generation of anti-pertussis vaccines with high bactericidal activities and biocompatibilities.

Effect of change in vaccine schedule on pertussis epidemiology in France: a modelling and serological study

BACKGROUND

In April-May, 2013, France modified its pertussis vaccination schedule, which uses the acellular pertussis vaccine, from three primary doses at 2, 3, and 4 months of age and a first booster at 16-18 months of age (former schedule) to two primary doses at 2 and 4 months of age and a first booster at 11 months of age (new schedule). We aimed to assess the subsequent effect of the vaccine schedule change on pertussis epidemiology in France.

METHODS

In this modelling study, using data collected between Jan 1, 2012, and Dec 31, 2019, from French national surveillance sources, we analysed the PCR test results of nasopharyngeal swabs collected from symptomatic outpatients aged 2-20 years with suspected pertussis. We developed a negative binomial regression model for the number of confirmed pertussis cases by year and age to assess the relative risks of pertussis depending on vaccine schedule. The linear predictor included the year, the age group, the population size, and a proxy of waning immunity. We tested different models in which waning immunity could vary with vaccine schedule and type of primary vaccine. The models were fitted to the 2012-18 data via Bayesian Markov chain Monte Carlo sampling, and the 2019 data were left out for external model validation. We also compared the anti-pertussis toxin (PT) antibody concentrations in leftover sera from children not tested for pertussis or recent respiratory tract infection aged 2-5 years born before and after the vaccine schedule change.

FINDINGS

We collected data on 7493 confirmed cases of pertussis. The model that best fitted the 2012-18 epidemiological data supported a faster waning of immunity following vaccination with the new vaccine schedule. 3 years after vaccination, the risk of developing pertussis was 1·7 (95% CI 1·4-2·0) times higher for children vaccinated according to the new schedule than those vaccinated according to the former schedule. The model correctly predicted the age distribution of cases in 2019. Geometric mean concentrations (GMC) of anti-PT IgG were 50% lower in children aged 2 years vaccinated with the new schedule (GMC=5·85 IU/mL [95% CI 4·08-8·39]) than in children of the same age vaccinated with the former schedule (GMC=11·62 IU/mL [95% CI 9·05-14·92]; p=0·0016), and 43% lower in children aged 3 years vaccinated with the new schedule (GMC=3·88 IU/mL [95% CI 2·82-5·34]) than those with the former schedule (GMC=6·80 IU/mL [95% CI 4·77-9·70]; p=0·026).

INTERPRETATION

A shorter-lived protection induced by the new vaccine schedule recommended in France since 2013 is associated with an increase of pertussis cases in children aged 2-5 years. If similar findings are observed in other countries and clinical trials, these findings should be considered in future pertussis vaccination policies.

FUNDING

INCEPTION, Labex-IBEID, Institut Pasteur, and Santé Publique France.

Immunogenicity of a new enhanced tetanus-reduced dose diphtheria-acellular pertussis (Tdap) vaccine against Bordetella pertussis in a murine model

Background

The necessity of the tetanus-reduced dose diphtheria-acellular pertussis (Tdap) vaccine in adolescence and adults has been emphasized since the resurgence of small-scale pertussis in Korea and worldwide due to the waning effect of the vaccine and variant pathogenic stains in the late 1990s. GreenCross Pharma (GC Pharma), a Korean company, developed the Tdap vaccine GC3111 in 2010. Recently, they enhanced the vaccine, GC3111, produced previously in 2010 to reinforce the antibody response against filamentous hemagglutinin (FHA). In this study, immunogenicity and efficacy of the enhanced Tdap vaccine compared and evaluated with two Tdap vaccines, GC3111 vaccine produced in 2010 previously and commercially available Tdap vaccine in a murine model.

Methods

Two tests groups and positive control group of Balb/c mice were primed with two doses of the diphtheria-tetanus-acellular pertussis (DTaP) vaccine followed by a single booster Tdap vaccine at 9 week using the commercially available Tdap vaccine or 2 Tdap vaccines from GC Pharma (GC3111, enhanced GC3111). Humoral response was assessed 1 week before and 2 and 4 weeks after Tdap booster vaccination. The enhanced GC3111 generated similar humoral response compare to the commercial vaccine for filamentous hemagglutinin (FHA). The interferon gamma (IFN-γ) (Th1), interleukin 5 (IL-5) (Th2) and interleukin 17 (IL-17) (Th17) cytokines were assessed 4 weeks after booster vaccination by stimulation with three simulators: heat inactivated Bordetella pertussis (hBp), vaccine antigens, and hBp mixed with antigens (hBp + antigen). A bacterial challenge test was performed 4 weeks after booster vaccination.

Results

Regarding cell-mediated immunity, cytokine secretion differed among the three simulators. However, no difference was found between two test groups and positive control group. All the vaccinated groups indicated a Th1 or Th1/Th2 response. On Day 5 post-bacterial challenge, B. pertussis colonies were absent in the lungs in two test groups and positive control group.

Conclusions

Our results confirmed the immunogenicity of GC Pharma’s Tdap vaccine; enhanced GC3111 was equivalent to the presently used commercial vaccine in terms of humoral response as well as cell-mediated cytokine expression.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12865-021-00457-1.

Pertussis Vaccine Candidate Based on Outer Membrane Vesicles Derived From Biofilm Culture

Outer membrane vesicles (OMV) derived from Bordetella pertussis-the etiologic agent of the resurgent disease called pertussis-are safe and effective in preventing bacterial colonization in the lungs of immunized mice. Vaccine formulations containing those OMV are capable of inducing a mixed Th1/Th2/Th17 profile, but even more interestingly, they may induce a tissue-resident memory immune response. This immune response is recommended for the new generation of pertussis-vaccines that must be developed to overcome the weaknesses of current commercial acellular vaccines (second-generation of pertussis vaccine). The third-generation of pertussis vaccine should also deal with infections caused by bacteria that currently circulate in the population and are phenotypically and genotypically different [in particular those deficient in the expression of pertactin antigen, PRN(-)] from those that circulated in the past. Here we evaluated the protective capacity of OMV derived from bacteria grown in biofilm, since it was observed that, by difference with older culture collection vaccine strains, circulating clinical B. pertussis isolates possess higher capacity for this lifestyle. Therefore, we performed studies with a clinical isolate with good biofilm-forming capacity. Biofilm lifestyle was confirmed by both scanning electron microscopy and proteomics. While scanning electron microscopy revealed typical biofilm structures in these cultures, BipA, fimbria, and other adhesins described as typical of the biofilm lifestyle were overexpressed in the biofilm culture in comparison with planktonic culture. OMV derived from biofilm (OMVbiof) or planktonic lifestyle (OMVplank) were used to formulate vaccines to compare their immunogenicity and protective capacities against infection with PRN(+) or PRN(-) B. pertussis clinical isolates. Using the mouse protection model, we detected that OMVbiof-vaccine was more immunogenic than OMVplank-vaccine in terms of both specific antibody titers and quality, since OMVbiof-vaccine induced antibodies with higher avidity. Moreover, when OMV were administered at suboptimal quantity for protection, OMVbiof-vaccine exhibited a significantly adequate and higher protective capacity against PRN(+) or PRN(-) than OMVplank-vaccine. Our findings indicate that the vaccine based on B. pertussis biofilm-derived OMV induces high protection also against pertactin-deficient strains, with a robust immune response.

Vaccine-Induced Cellular Immunity against Bordetella pertussis: Harnessing Lessons from Animal and Human Studies to Improve Design and Testing of Novel Pertussis Vaccines

Pertussis ('whooping cough') is a severe respiratory tract infection that primarily affects young children and unimmunised infants. Despite widespread vaccine coverage, it remains one of the least well-controlled vaccine-preventable diseases, with a recent resurgence even in highly vaccinated populations. Although the exact underlying reasons are still not clear, emerging evidence suggests that a key factor is the replacement of the whole-cell (wP) by the acellular pertussis (aP) vaccine, which is less reactogenic but may induce suboptimal and waning immunity. Differences between vaccines are hypothesised to be cell-mediated, with polarisation of Th1/Th2/Th17 responses determined by the composition of the pertussis vaccine given in infancy. Moreover, aP vaccines elicit strong antibody responses but fail to protect against nasal colonisation and/or transmission, in animal models, thereby potentially leading to inadequate herd immunity. Our review summarises current knowledge on vaccine-induced cellular immune responses, based on mucosal and systemic data collected within experimental animal and human vaccine studies. In addition, we describe key factors that may influence cell-mediated immunity and how antigen-specific responses are measured quantitatively and qualitatively, at both cellular and molecular levels. Finally, we discuss how we can harness this emerging knowledge and novel tools to inform the design and testing of the next generation of improved infant pertussis vaccines.

Circulation of Bordetella pertussis in vaccinated Cambodian children: A transversal serological study

BACKGROUND

The Cambodia pertussis immunization schedule includes three doses given at age 6, 10 and 14 weeks using a whole-pertussis vaccine. No booster doses are included. Pertussis biological diagnosis is unavailable in Cambodia and its burden remains unclear. This study aimed to provide accurate data on pertussis serological status of Cambodian children and adolescents, and to evaluate vaccination timeliness.

METHODS

Fully vaccinated children aged 3-15 years were recruited at the Rabies Prevention Center, Institut Pasteur in Cambodia, Phnom Penh. Capillary blood samples and information on pertussis vaccination history were collected. Anti-pertussis toxin (PT) IgG titers were quantified by ELISA.

RESULTS

Compliance with the national immunization schedule was 95.1%. Initiation of vaccination after 8 weeks of age was observed for 29.0% of the children, but was less frequent in the youngest children (13.0%) compared with the oldest ones (46.4%). Rate of children exhibiting anti-PT IgG varied across age groups, and increased from 35.7% to 55.0% in 3-5 and 12-15 years age groups, respectively.

CONCLUSION

Pertussis circulates among vaccinated Cambodian children and adolescents. These data support the need for public health authorities to strengthen pertussis surveillance and use local epidemiological data to make evidence-based decision for the establishment of an optimal vaccination strategy.

Controlled Human Infection With Bordetella pertussis Induces Asymptomatic, Immunizing Colonization

Background

Bordetella pertussis is among the leading causes of vaccine-preventable deaths and morbidity globally. Human asymptomatic carriage as a reservoir for community transmission of infections might be a target of future vaccine strategies, but has not been demonstrated. Our objective was to demonstrate that asymptomatic nasopharyngeal carriage of Bordetella pertussis is inducible in humans and to define the microbiological and immunological features of presymptomatic infection.

Methods

Healthy subjects aged 18–45 years with an antipertussis toxin immunoglobin G (IgG) concentration of <20 international units/ml were inoculated intranasally with nonattenuated, wild-type Bordetella pertussis strain B1917. Safety, colonization, and shedding were monitored over 17 days in an inpatient facility. Colonization was assessed by culture and quantitative polymerase chain reaction. Azithromycin was administered from Day 14. The inoculum dose was escalated, aiming to colonize at least 70% of participants. Immunological responses were measured.

Results

There were 34 participants challenged, in groups of 4 or 5. The dose was gradually escalated from 10³ colony-forming units (0% colonized) to 10⁵ colony-forming units (80% colonized). Minor symptoms were reported in a minority of participants. Azithromycin eradicated colonization in 48 hours in 88% of colonized individuals. Antipertussis toxin IgG seroconversion occurred in 9 out of 19 colonized participants and in none of the participants who were not colonized. Nasal wash was a more sensitive method to detect colonization than pernasal swabs. No shedding of Bordetella pertussis was detected in systematically collected environmental samples.

Conclusions

Bordetella pertussis colonization can be deliberately induced and leads to a systemic immune response without causing pertussis symptoms.

Clinical Trials Registration

NCT03751514.

Interacting, Nonspecific, Immunological Effects of Bacille Calmette-Guérin and Tetanus-diphtheria-pertussis Inactivated Polio Vaccinations: An Explorative, Randomized Trial

BACKGROUND

Certain vaccines, such as Bacille Calmette-Guérin (BCG), have nonspecific effects, which modulate innate immune responses and lead to protection against mortality from unrelated infections (trained immunity). In contrast, in spite of the disease-specific effects, an enhanced overall mortality has been described after diphtheria-tetanus-pertussis (DTP) vaccination in females. This randomized trial aimed to investigate the nonspecific immunological effects of BCG and DTP-containing vaccines on the immune response to unrelated pathogens.

METHODS

We randomized 75 healthy, female, adult volunteers to receive either BCG, followed by a booster dose of tetanus-diphtheria-pertussis inactivated polio vaccine (Tdap) 3 months later; BCG and Tdap combined; or Tdap followed by BCG 3 months later. Blood was collected before vaccination, as well as at 1 day, 4 days, 2 weeks, and 3 months after the first vaccination(s), plus 2 weeks after the second vaccination. Ex vivo leukocyte responses to unrelated stimuli and pathogens were assessed.

RESULTS

Tdap vaccination led to short-term potentiation and long-term repression of monocyte-derived cytokine responses, and short-term as well as long-term repression of T-cell reactivity to unrelated pathogens. BCG led to short-term and long-term potentiation of monocyte-derived cytokine responses. When given together with Tdap or after Tdap, BCG abrogated the immunosuppressive effects of Tdap vaccination.

CONCLUSIONS

Tdap induces immunotolerance to unrelated antigens, which is partially restored by concurrent or subsequent BCG vaccination. These data indicate that the modulation of heterologous immune responses is induced by vaccination with Tdap and BCG, and more studies are warranted to investigate whether this is involved in the nonspecific effects of vaccines on mortality.

CLINICAL TRIALS REGISTRATION

NCT02771782.

Efficacy, safety, and formulation issues of the combined vaccines

Introduction: Controlling the preventable infectious diseases is the main goal of vaccination. Among the vaccines, combined vaccines are of great importance for their social, public health, and economic values. It is stated that the combined vaccines are as efficient and safe as the monovalent vaccines. However, a concern has raised about the efficacy and safety of the combined vaccines due to the outbreaks of vaccine-preventable diseases and occurrence of serious adverse events. Areas covered: A retrospective literature search was conducted in the Google Scholar and PubMed databases to evaluate the efficacy and safety of the combined vaccines from 1980 to 2020 using appropriate keywords. Expert opinion: Several studies have shown efficacy and safety issues related to the combined vaccines. Different factors contribute to the inefficacy and lack of safety in the vaccines including formulation problems, limited data in the pre-licensure studies and challenges related to imperfection of the post-licensure surveillance systems. For surmounting the mentioned obstacles, there is a need to provide new formulations of the vaccines, revise the vaccines҆ safety and efficacy acceptance standards in the pre-licensure studies, improvement of post-licensure surveillance systems, and education of healthcare staff.

Risk factors for Bordetella pertussis disease in hospitalized children

INTRODUCTION

Despite a resurgence of disease, risk factors for pertussis in children in low and middle-income countries are poorly understood. This study aimed to investigate risk factors for pertussis disease in African children hospitalized with severe LRTI.

METHODS

A prospective study of children hospitalized with severe LRTI in Cape Town, South Africa was conducted over a one-year period. Nasopharyngeal and induced sputum samples from child and nasopharyngeal sample from caregiver were tested for Bordetella pertussis using PCR (IS481+/hIS1001). History and clinical details were documented.

RESULTS

460 children with a median age of 8 (IQR 4-18) months were enrolled. B. pertussis infection was confirmed in 32 (7.0%). The adjusted risk of confirmed pertussis was significantly increased if infants were younger than two months [aRR 2.37 (95% CI 1.03-5.42]), HIV exposed but uninfected (aRR 3.53 [95% CI 1.04-12.01]) or HIV infected (aRR 4.35 [95% CI 1.24-15.29]). Mild (aRR 2.27 [95% CI 1.01-5.09]) or moderate (aRR 2.70 [95% CI 1.13-6.45]) under-nutrition in the children were also associated with higher risk. The highest adjusted risk occurred in children whose caregivers had B. pertussis detected from nasopharyngeal swabs (aRR 13.82 [95% CI 7.76-24.62]). Completion of the primary vaccine schedule (three or more doses) was protective (aRR 0.28 [95% CI 0.10-0.75]).

CONCLUSIONS

HIV exposure or infection, undernutrition as well as detection of maternal nasal B. pertussis were associated with increased risk of pertussis in African children, especially in young infants. Completed primary vaccination was protective. There is an urgent need to improve primary pertussis vaccine coverage in low and middle-income countries. Pertussis vaccination of pregnant women, especially those with HIV infection should be prioritized.

Clinical and epidemiological features of pertussis in Salvador, Brazil, 2011-2016

Pertussis, a severe respiratory infection caused by Bordetella pertussis, is distributed globally. Vaccination has been crucial to annual reductions in the number of cases. However, disease reemergence has occurred over the last decade in several countries, including Brazil. Here we describe the clinical and epidemiological aspects of suspected pertussis cases in Salvador, Brazil, and evaluate factors associated with case confirmation. This descriptive and retrospective study was conducted in the five hospitals in Salvador that reported the highest number of pertussis cases between 2011-2016. Demographic and clinical data were recorded for each patient. Bivariate analysis was performed to evaluate differences between groups (confirmed vs. unconfirmed cases) using Pearson's Chi-square test or Fisher's exact test. Results: Of 529 suspected pertussis cases, 29.7% (157/529) were confirmed by clinical, clinical-epidemiological or laboratory criteria, with clinical criteria most frequently applied (63.7%; 100/157). Unvaccinated individuals (43.3%; 68/157) were the most affected, followed by age groups 2-3 months (37.6%; 59/157) and <2 months (31.2%; 49/157). Overall, ≤50% of the confirmed cases presented a complete vaccination schedule. All investigated cases presented cough in association with one or more symptoms, especially paroxysmal cough (66.9%; 105/529) (p = 0.001) or cyanosis (66.2%; 104/529) (p<0.001). Our results indicate that pertussis occurred mainly in infants and unvaccinated individuals in Salvador, Brazil. The predominance of clinical criteria used to confirm suspected cases highlights the need for improvement in the laboratory tools used to perform rapid diagnosis. Fluctuations in infection prevalence demonstrate the importance of vaccination strategies in improving the control and prevention of pertussis.

Transversal sero-epidemiological study of Bordetella pertussis in Tehran, Iran

Objectives

Pertussis remains endemic despite high vaccine coverage in infants and toddlers. Pertussis vaccines confer protection but immunity wanes overtime and boosters are needed in a lifetime. Iran, eligible for the Expanded Program on Immunization that includes the primary immunization, implemented two additional booster doses using a whole-cell vaccine (wPV) at 18 months-old and about 6 years-old. Duration of protection induced by the wPVs currently in use and their impact as pre-school booster are not well documented. This study aimed at assessing vaccination compliance and at estimating the duration of protection conferred by vaccination with wPV in children aged < 15 years in Tehran, Iran.

Methods

Detailed information on vaccination history and capillary blood samples were obtained from 1047 children aged 3–15 years who completed the 3 doses-primary pertussis immunization, in Tehran. Anti-pertussis toxin IgG levels were quantified by ELISA.

Results

Compliance was very high with 93.3% of children who received the three primary and 1^st booster doses in a timely manner. Timeliness of the 2^nd booster was lower (63.3%). Rate of seropositive samples continuously and significantly increased from 1–2 to 5–6 years after 1^st booster attaining 30.4% of children exhibiting serological sign of recent contact with B. pertussis. Second booster dating back 1 or 2 years was associated with high antibody titers, which significantly decreased within 3 years from injection. Among children who received 2^nd booster injection more than 2 years before serum analysis, seroprevalence of pertussis infection was 8.4% and seropositivity rate was higher from the 10 years-old group.

Conclusion

Seropositivity in children aged 6–7 years with no 2^nd booster supports the need for a vaccination at that age. Adolescent booster may also be considered.

Pertussis vaccination in mixed markets: Recommendations from the Global Pertussis Initiative

The Global Pertussis Initiative is an expert scientific forum that publishes consensus recommendations concerning pertussis for many regions of the world. Here, we give recommendations for the primary vaccination of infants in those countries where whole-cell pertussis (wP)- and acellular pertussis (aP)-containing combination vaccines are used in parallel. A selective literature review was performed concerning the influence on safety, immunogenicity, and effectiveness of mixing wP- and aP-containing vaccines for primary immunization of infants. In addition, local data were collected from various countries and the results discussed in a face-to-face meeting. Very few data addressing issues of mixing combination vaccines were identified, and no data were available concerning the effectiveness or duration of protection. It was also found that pharmacovigilance data are scarce or lacking in those countries where they would be needed the most. We then identified frequent problems occurring in low- and middle-income countries (LMICs) where both vaccine types are used. Relying on local knowledge, we give practical recommendations for a variety of situations in different settings. Specific needs for additional data addressing these issues were also identified. International bodies, such as the World Health Organization (WHO), as well as vaccine producers should try to find ways to highlight the problems of mixing wP- and aP-containing combination vaccines with robust data. Countries are urged to improve on their pharmacovigilance for vaccines. For practicing physicians, our recommendations offer guidance when wP- and aP-containing vaccines are used in parallel during primary immunization.

Anti-infective vaccination strategies in patients with hematologic malignancies or solid tumors-Guideline of the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Medical Oncology (DGHO)

Infectious complications are a significant cause of morbidity and mortality in patients with malignancies specifically when receiving anticancer treatments. Prevention of infection through vaccines is an important aspect of clinical care of cancer patients. Immunocompromising effects of the underlying disease as well as of antineoplastic therapies need to be considered when devising vaccination strategies. This guideline provides clinical recommendations on vaccine use in cancer patients including autologous stem cell transplant recipients, while allogeneic stem cell transplantation is subject of a separate guideline. The document was prepared by the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Medical Oncology (DGHO) by reviewing currently available data and applying evidence-based medicine criteria.

Pertussis in Latin America: Recent epidemiological data presented at the 2017 Global Pertussis Initiative meeting

The Global Pertussis Initiative (GPI) is an expert scientific forum that publishes consensus recommendations for pertussis monitoring, prevention, and treatment across many regions of the world. Here, we report on the regional 2017 GPI meeting on the Americas, focusing on Latin America. Information on current pertussis epidemiology, surveillance, vaccine strategies, diagnostic capabilities, disease awareness, and major local obstacles was presented by researchers from Argentina, Brazil, Colombia, Costa Rica, El Salvador, Mexico, Peru, Puerto Rico, Uruguay, and Venezuela. Pertussis outbreaks have occurred during the last decade in the majority of participant countries and have been followed by improvements in surveillance. In the countries that introduced maternal immunization during pregnancy, a reduction in the infant case fatality rate has been detected. All countries need to maintain and improve pertussis surveillance to reach primary vaccination coverage >90%. Moreover, countries without maternal immunization programs should strongly consider them.

Fc Glycan-Mediated Regulation of Placental Antibody Transfer

Despite the worldwide success of vaccination, newborns remain vulnerable to infections. While neonatal vaccination has been hampered by maternal antibody-mediated dampening of immune responses, enhanced regulatory and tolerogenic mechanisms, and immune system immaturity, maternal pre-natal immunization aims to boost neonatal immunity via antibody transfer to the fetus. However, emerging data suggest that antibodies are not transferred equally across the placenta. To understand this, we used systems serology to define Fc features associated with antibody transfer. The Fc-profile of neonatal and maternal antibodies differed, skewed toward natural killer (NK) cell-activating antibodies. This selective transfer was linked to digalactosylated Fc-glycans that selectively bind FcRn and FCGR3A, resulting in transfer of antibodies able to efficiently leverage innate immune cells present at birth. Given emerging data that vaccination may direct antibody glycosylation, our study provides insights for the development of next-generation maternal vaccines designed to elicit antibodies that will most effectively aid neonates.

Assessment of humoral and cell-mediated immune responses to pertussis vaccination: a systematic review protocol

INTRODUCTION

Globally, some studies show a resurgence of pertussis. The risks and benefits of using whole-cell pertussis (wP) or acellular pertussis (aP) vaccines in the control of the disease have been widely debated. Better control of pertussis will require improved understanding of the immune response to pertussis vaccines. Improved understanding and assessment of the immunity induced by pertussis vaccines is thus imperative. Several studies have documented different immunological outcomes to pertussis vaccination from an array of assays. We propose to conduct a systematic review of the different immunological assays and outcomes used in the assessment of the humoraland cell-mediated immune response following pertussis vaccination.

METHODS AND ANALYSIS

The primary outcomes for consideration are quality and quantity of immune responses (humoral and cell-mediated) post-pertussis vaccination. Of interest as secondary outcomes are types of immunoassays used in assessing immune responses post-pertussis vaccination, types of biological samples used in assessing immune responses post-pertussis vaccination, as well as the types of antigens used to stimulate these samples during post-pertussis vaccination immune response assessments. Different electronic databases (including PubMed, Cochrane, EBSCO Host, Scopus and Web of Science) will be accessed for peer-reviewed published and grey literature evaluating immune responses to pertussis vaccines between 1990 and 2019. The quality of included articles will be assessed using standardised risk and quality assessment tools specific to the study design used in each article. Data extraction will be done using a data extraction form. The extracted data will be analysed using STATA V.14.0 and RevMan V.5.3 software. A subgroup analysis will be conducted based on the study population, type of vaccine (wP or aP) and type of immune response (cell-mediated or humoral). Guidelines for reporting systematic reviews in the revised 2009 Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement will be used in this study.

ETHICS AND DISSEMINATION

Ethics approval is not required for this study as it is a systematic review. We will only make use of data already available in the public space. Findings will be reported via publication in a peer-reviewed journal and presented at scientific meetings and workshops.

TRIAL REGISTRATION NUMBER

CRD42018102455.

Bordetella pertussis in a four-time kidney transplant recipient: A call for immunization programs at transplant centers

Pertussis, or whooping cough, is a highly contagious respiratory illness caused most frequently by Bordetella pertussis. Clinical presentation ranges in severity, but life-threatening illness disproportionately affects children and immunocompromised individuals. Acellular vaccines for pertussis have been available for decades, and they are recommended throughout the lifespan. A patient who had received a kidney transplant presented with respiratory distress and dry cough as manifestations of co-infection with B pertussis and Bordetella parapertussis/bronchiseptica. The goal of this case report was to highlight the importance of immunization programs at transplant centers, which are in the unique position to care for patients both with end-stage organ disease and in the post-transplant setting.

Recombinant outer membrane protein Q and putative lipoprotein from Bordetella pertussis inducing strong humoral response were not protective alone in the murine lung colonization model

Despite high vaccination coverage after introduction of whole cell (wP) and acellular pertussis (aP) vaccines, pertussis resurgence has been reported in many countries. aP vaccines are commonly preferred due to side effects of wP vaccines and formulated with aluminum hydroxide (Alum), which is not an effective adjuvant to eliminate Bordetella pertussis. Low efficiency of current aP vaccines is thought to be the main reason for the resurgence for which newer generation aP vaccines are needed. In the present study, immunogenicity and protective efficacy of outer membrane protein Q (OmpQ) and a putative lipoprotein (Lpp) from B. pertussis were investigated in mice by using two diefrent adjuvants, monophosphoryl lipid A (MPLA) or Alum. OmpQ and putative Lpp were cloned, expressed, and purified from Escherichia coli. The proteins were formulated to immunize mice. Both recombinant OmpQ and putative Lpp induced a significant increase in immunoglobulin G1 (IgG1) and immunoglobulin G2a (IgG2a) responses compared to the control group. Moreover, MPLA-adjuvanted formulations resulted in higher IgG2a levels than Alum-adjuvanted ones. However, there were no significant differences between test and control groups regarding interferon-gamma (IFN-γ) levels, and the mice lung colonization experiments indicated that neither rOmpQ nor rLpp could confer protection alone against B. pertussis challenge.

Immunogenicity and protective potential of Bordetella pertussis biofilm and its associated antigens in a murine model

The resurgence of whooping cough reflects novel genetic variants of Bordetella pertussis and inadequate protection conferred by current acellular vaccines (aP). Biofilm is a source of novel vaccine candidates, including membrane protein assembly factor (BamB) and lipopolysaccharide assembly protein (LptD). Responses of BALB/c mice to candidate vaccines included IFN-γ and IL-17a production by spleen and lymph node cells, and serum IgG1 and IgG2a reactive with whole bacteria or aP. Protection was determined using bacterial cultured from lungs of vaccinated mice challenged with virulent B. pertussis. Mice vaccinated with biofilm produced efficient IFN-γ responses and more IL-17a and IgG2a than mice vaccinated with planktonic cells, aP or adjuvant alone. Vaccination with aP produced abundant IgG1 with little IgG2a. Mice vaccinated with aP plus BamB and LptD retained lower bacterial loads than mice vaccinated with aP alone. Whooping cough vaccines formulated with biofilm antigens, including BamB and LptD, may have clinical value.

Human Immune Responses to Pertussis Vaccines

Pertussis still represents a major cause of morbidity and mortality worldwide. Although vaccination is the most powerful tool in preventing pertussis and despite nearly 70 years of universal childhood vaccination, incidence of the disease has been rising in the last two decades in countries with high vaccination coverage. Two types of vaccines are commercially available against pertussis: whole-cell pertussis vaccines (wPVs) introduced in the 1940s and still in use especially in low and middle-income countries; less reactogenic acellular pertussis vaccines (aPVs), licensed since the mid-1990s.In the last years, studies on pertussis vaccination have highlighted significant gaps and major differences between the two types of vaccines in the induction of protective anti-pertussis immunity in humans. This chapter will discuss the responses of the immune system to wPVs and aPVs, with the aim to enlighten critical points needing further efforts to reach a good level of protection in vaccinated individuals.

A Review on T Cell Epitopes Identified Using Prediction and Cell-Mediated Immune Models for Mycobacterium tuberculosis and Bordetella pertussis

In the present review, we summarize work from our as well as other groups related to the characterization of bacterial T cell epitopes, with a specific focus on two important pathogens, namely, Mycobacterium tuberculosis (Mtb), the bacterium that causes tuberculosis (TB), and Bordetella pertussis (BP), the bacterium that causes whooping cough. Both bacteria and their associated diseases are of large societal significance. Although vaccines exist for both pathogens, their efficacy is incomplete. It is widely thought that defects and/or alteration in T cell compartments are associated with limited vaccine effectiveness. As discussed below, a full genome-wide map was performed in the case of Mtb. For BP, our focus has thus far been on the antigens contained in the acellular vaccine; a full genome-wide screen is in the planning stage. Nevertheless, the sum-total of the results in the two different bacterial systems allows us to exemplify approaches and techniques that we believe are generally applicable to the mapping and characterization of human immune responses to bacterial pathogens. Finally, we add, as a disclaimer, that this review by design is focused on the work produced by our laboratory as an illustration of approaches to the study of T cell responses to Mtb and BP, and is not meant to be comprehensive, nor to detract from the excellent work performed by many other groups.

Vaccines in pediatric transplant recipients-Past, present, and future

Infections significantly impact outcomes for solid organ and hematopoietic stem cell transplantation in children. Vaccine-preventable diseases contribute to morbidity and mortality in both early and late posttransplant time periods. Several infectious diseases and transplantation societies have published recommendations and guidelines that address immunization in adult and pediatric transplant recipients. In many cases, pediatric-specific studies are limited in size or quality, leading to recommendations being based on adult data or mixed adult-pediatric studies. We therefore review the current state of evidence for selected immunizations in pediatric transplant recipients and highlight areas for future investigation. Specific attention is given to studies that enrolled only children.

Low levels of detectable pertussis antibody among a large cohort of pregnant women in Canada

Newborns and infants less than 6 months of age continue to be at highest risk of severe outcomes from pertussis infection. Pertussis vaccination during the last trimester of pregnancy can confer protection to newborns as a result of trans-placental transfer of pertussis antibodies. In several countries, pertussis vaccination in pregnancy is recommended routinely and Canada's National Advisory Committee on Immunization issued similar routine recommendations in February 2018. Using second trimester biobanked plasma samples (n = 1752) collected between 2008 and 2011, we measured the pre-existing anti-pertussis toxin (PT) levels in a large cohort of second-trimester pregnant women using a commercial ELISA test. We found that 97.5% of these women had anti-PT IgG titres below 35 IU/mL. Women with higher incomes had slightly higher anti-PT levels but 96% still had titres <35 IU/ml. In conclusion, almost all of the pregnant women in this large cohort had anti-PT levels low enough to suggest susceptibility to pertussis infection in both the mothers and their newborn infants.

Th1/Th17 polarization persists following whole-cell pertussis vaccination despite repeated acellular boosters

In the mid-1990s, whole-cell pertussis (wP) vaccines were associated with local and systemic adverse events that prompted their replacement with acellular pertussis (aP) vaccines in many high-income countries. In the past decade, rates of pertussis disease have increased in children receiving only aP vaccines. We compared the immune responses to aP boosters in individuals who received their initial doses with either wP or aP vaccines using activation-induced marker (AIM) assays. Specifically, we examined pertussis-specific memory CD4+ T cell responses ex vivo, highlighting a type 2/Th2 versus type 1/Th1 and Th17 differential polarization as a function of childhood vaccination. Remarkably, after a contemporary aP booster, cells from donors originally primed with aP were (a) associated with increased IL-4, IL-5, IL-13, IL-9, and TGF-β and decreased IFN-γ and IL-17 production, (b) defective in their ex vivo capacity to expand memory cells, and (c) less capable of proliferating in vitro. These differences appeared to be T cell specific, since equivalent increases of antibody titers and plasmablasts after aP boost were seen in both groups. In conclusion, our data suggest that there are long-lasting effects and differences in polarization and proliferation of T cell responses in adults originally vaccinated with aP compared with those that initially received wP, despite repeated acellular boosters.

Experience and challenges on influenza and pertussis vaccination in pregnant women

Young infants contribute to relatively high burden of vaccine-preventable diseases, including infections by influenza virus and Bordetella pertussis. Vaccination of pregnant women can enhance transplacental transfer of protective antibody to the fetus and protect the infant against disease during the first few months of life.

Pregnant women are a priority group for seasonal influenza vaccination, due to third-trimester pregnancy being a risk-factor for severe influenza illness. Furthermore, randomized controlled trials confirmed that influenza vaccination during pregnancy confers protection against influenza-confirmed illness in the women, and their infants up to 3 months of age; and is also associated with 20% reduction in all-cause pneumonia among young-infants. Maternal influenza vaccination might also reduce the risk of low-birth weight, preterm births, and stillbirths however, data on this is conflicting.

Vaccination of pregnant women with acellular pertussis vaccines reduces pertussis in their young infants by up to 93%. The increase in specific pertussis antibody among the infants born to vaccinated women might, however, interfere with the active pertussis vaccination of the infant following the primary series of vaccines. The clinical implication of this is yet to be ascertained, particularly since immune responses following the booster vaccine are unaffected.

Vaccination of pregnant women with inactivated influenza vaccine and acellular pertussis vaccine have been demonstrated to confer protection to their young infants, and warrants consideration for inclusion into public health immunization programs, including in low and middle income countries.

Primary transcriptome analysis reveals importance of IS elements for the shaping of the transcriptional landscape of Bordetella pertussis

Bordetella pertussis is the causative agent of whooping cough, a respiratory disease still considered as a major public health threat and for which recent re-emergence has been observed. Constant reshuffling of Bordetella pertussis genome organization was observed during evolution. These rearrangements are essentially mediated by Insertion Sequences (IS), a mobile genetic elements present in more than 230 copies in the genome, which are supposed to be one of the driving forces enabling the pathogen to escape from vaccine-induced immunity. Here we use high-throughput sequencing approaches (RNA-seq and differential RNA-seq), to decipher Bordetella pertussis transcriptome characteristics and to evaluate the impact of IS elements on transcriptome architecture. Transcriptional organization was determined by identification of transcription start sites and revealed also a large variety of non-coding RNAs including sRNAs, leaderless mRNAs or long 3' and 5'UTR including seven riboswitches. Unusual topological organizations, such as overlapping 5'- or 3'-extremities between oppositely orientated mRNA were also unveiled. The pivotal role of IS elements in the transcriptome architecture and their effect on the transcription of neighboring genes was examined. This effect is mediated by the introduction of IS harbored promoters or by emergence of hybrid promoters. This study revealed that in addition to their impact on genome rearrangements, most of the IS also impact on the expression of their flanking genes. Furthermore, the transcripts produced by IS are strain-specific due to the strain to strain variation in IS copy number and genomic context.

What Is Wrong with Pertussis Vaccine Immunity? The Problem of Waning Effectiveness of Pertussis Vaccines

Pertussis is resurgent in some countries, particularly those in which children receive acellular pertussis (aP) vaccines in early infancy and boosters later in life. Immunologic studies show that, whereas whole-cell pertussis (wP) vaccines orient the immune system toward Th1/Th17 responses, acellular pertussis vaccines orient toward Th1/Th2 responses. Although aP vaccines do provide protection during the first years of life, the change in T-cell priming results in waning effectiveness of aP as early as 2-3 years post-boosters. Although other factors, such as increased virulence of pertussis strains, better diagnosis, and better surveillance may play a role, the increase in pertussis appears to be the result of waning immunity. In addition, studies in baboon models, requiring confirmation in humans, show that aP is less able to prevent nasopharyngeal colonization of Bordetella pertussis than wP or natural infection.

Geospatial analysis of nonmedical vaccine exemptions and pertussis outbreaks in the United States

Because of increased numbers of recorded pertussis cases in the United States, this study sought to understand the role of nonmedical vaccine exemptions and waning immunity may have had on the resurgence of pertussis in the United States at the community level. We used geospatial scan statistics, SaTScan, version 9.4, to analyze nonmedical vaccine exemptions of children entering kindergarten in 2011 and 2012 and reported pertussis cases in 2012 for children in age groups 5 years and younger and 10 to 14 years. Eight statistically significant clusters of nonmedical vaccine exemptions in kindergarteners and 11 statistically significant clusters of pertussis cases in children and adolescents were identified and geospatially linked. Forty-five percent of the counties in the study had high rates of nonmedical vaccine exemptions. The proportion of kindergarteners with nonmedical vaccine exemptions was 2.8 times larger in the identified exemption clusters. In addition, 31 counties had geographic clusters of high rates of pertussis in children ages 10 to 14 years old, consistent with waning immunity. Our findings are consistent with the view that geographic clusters of nonmedical vaccine exemptions and waning immunity may have been factors contributing to community-level pertussis outbreaks.

Bordetella PlrSR regulatory system controls BvgAS activity and virulence in the lower respiratory tract

Bacterial pathogens coordinate virulence using two-component regulatory systems (TCS). The Bordetella virulence gene (BvgAS) phosphorelay-type TCS controls expression of all known protein virulence factor-encoding genes and is considered the "master virulence regulator" in Bordetella pertussis, the causal agent of pertussis, and related organisms, including the broad host range pathogen Bordetella bronchiseptica We recently discovered an additional sensor kinase, PlrS [for persistence in the lower respiratory tract (LRT) sensor], which is required for B. bronchiseptica persistence in the LRT. Here, we show that PlrS is required for BvgAS to become and remain fully active in mouse lungs but not the nasal cavity, demonstrating that PlrS coordinates virulence specifically in the LRT. PlrS is required for LRT persistence even when BvgAS is rendered constitutively active, suggesting the presence of BvgAS-independent, PlrS-dependent virulence factors that are critical for bacterial survival in the LRT. We show that PlrS is also required for persistence of the human pathogen B. pertussis in the murine LRT and we provide evidence that PlrS most likely functions via the putative cognate response regulator PlrR. These data support a model in which PlrS senses conditions present in the LRT and activates PlrR, which controls expression of genes required for the maintenance of BvgAS activity and for essential BvgAS-independent functions. In addition to providing a major advance in our understanding of virulence regulation in Bordetella, which has served as a paradigm for several decades, these results indicate the existence of previously unknown virulence factors that may serve as new vaccine components and therapeutic or diagnostic targets.

Definition of Human Epitopes Recognized in Tetanus Toxoid and Development of an Assay Strategy to Detect Ex Vivo Tetanus CD4+ T Cell Responses

Despite widespread uses of tetanus toxoid (TT) as a vaccine, model antigen and protein carrier, TT epitopes have been poorly characterized. Herein we defined the human CD4⁺ T cell epitope repertoire by reevaluation of previously described epitopes and evaluation of those derived from prediction of HLA Class II binding. Forty-seven epitopes were identified following in vitro TT stimulation, with 28 epitopes accounting for 90% of the total response. Despite this diverse range of epitopes, individual responses were associated with only a few immunodominant epitopes, with each donor responding on average to 3 epitopes. For the top 14 epitopes, HLA restriction could be inferred based on HLA typing of the responding donors. HLA binding predictions re-identified the vast majority of known epitopes, and identified 24 additional novel epitopes. With these epitopes, we created a TT epitope pool, which allowed us to characterize TT responses directly ex vivo using a cytokine-independent Activation Induced Marker (AIM) assay. These TT responses were highly Th1 or Th2 polarized, which was dependent upon the original priming vaccine, either the cellular DTwP or acellular DTaP formulation. This polarization remained despite the original priming having occurred decades past and a recent booster immunization with a reduced acellular vaccine formulation. While TT responses following booster vaccination were not durably increased in magnitude, they were associated with a relative expansion of CD4⁺ effector memory T cells.

Infectious diseases in allogeneic haematopoietic stem cell transplantation: prevention and prophylaxis strategy guidelines 2016

Infectious complications after allogeneic haematopoietic stem cell transplantation (allo-HCT) remain a clinical challenge. This is a guideline provided by the AGIHO (Infectious Diseases Working Group) of the DGHO (German Society for Hematology and Medical Oncology). A core group of experts prepared a preliminary guideline, which was discussed, reviewed, and approved by the entire working group. The guideline provides clinical recommendations for the preventive management including prophylactic treatment of viral, bacterial, parasitic, and fungal diseases. The guideline focuses on antimicrobial agents but includes recommendations on the use of vaccinations. This is the updated version of the AGHIO guideline in the field of allogeneic haematopoietic stem cell transplantation utilizing methods according to evidence-based medicine criteria.

Pertussis: Microbiology, Disease, Treatment, and Prevention

Pertussis is a severe respiratory infection caused by Bordetella pertussis, and in 2008, pertussis was associated with an estimated 16 million cases and 195,000 deaths globally. Sizeable outbreaks of pertussis have been reported over the past 5 years, and disease reemergence has been the focus of international attention to develop a deeper understanding of pathogen virulence and genetic evolution of B. pertussis strains. During the past 20 years, the scientific community has recognized pertussis among adults as well as infants and children. Increased recognition that older children and adolescents are at risk for disease and may transmit B. pertussis to younger siblings has underscored the need to better understand the role of innate, humoral, and cell-mediated immunity, including the role of waning immunity. Although recognition of adult pertussis has increased in tandem with a better understanding of B. pertussis pathogenesis, pertussis in neonates and adults can manifest with atypical clinical presentations. Such disease patterns make pertussis recognition difficult and lead to delays in treatment. Ongoing research using newer tools for molecular analysis holds promise for improved understanding of pertussis epidemiology, bacterial pathogenesis, bioinformatics, and immunology. Together, these advances provide a foundation for the development of new-generation diagnostics, therapeutics, and vaccines.

Transiently increased IgE responses in infants and pre-schoolers receiving only acellular Diphtheria-Pertussis-Tetanus (DTaP) vaccines compared to those initially receiving at least one dose of cellular vaccine (DTwP) - Immunological curiosity or canary in the mine?

BACKGROUND

Several previous studies have highlighted the strong Th2-polarising and IgE-promoting activity of the DTaP vaccine, but there is no evidence that this has pathological consequences and accordingly there is no current interest amongst vaccine developers in reformulating DTaP to attenuate these properties. In light of an apparent resurgence in pertussis in many countries, and emerging evidence from other areas of paediatric immunology of IgE-mediated interference with host defence mechanisms, this issue requires more detailed clarification.

METHODS

We have re-evaluated the impact of DTaP-only versus mixed DTwP/DTaP vaccination on Th2-dependent "bystander" IgE responses in three cohorts of children under different priming conditions, encompassing both vaccine-targeted and unrelated antigens including food allergens.

RESULTS

We confirm the generalised IgE-trophic activity of the DTaP vaccine in pre-schoolers and demonstrate similar (albeit transient) effects in infants. We additionally demonstrate that use of an alternative mixed infant priming schedule encompassing an initial dose of DTwP significantly attenuates this property.

INTERPRETATION

Central to our interpretation of these findings are studies demonstrating: (i) mixed DTwP/DTaP priming improves resistance to pertussis disease and attenuates the IgE-stimulatory component of long term vaccine-specific memory; (ii) IgE-mediated mechanisms can interfere with innate antiviral immunity and accordingly exacerbate airway symptoms in infected children. These observations, taken together with the data presented here, suggest a plausible mechanistic link between baseline pertussis-specific IgE titres in DTaP vaccinees and susceptibility to pertussis disease, which merits testing. Retrospective IgE analyses on sera collected from children at the time of presentation with pertussis could resolve this issue.

Rediscovering Pertussis

Pertussis, caused by Bordetella (B.) pertussis, a Gram-negative bacterium, is a highly contagious airway infection. Especially in infants, pertussis remains a major health concern. Acute infection with B. pertussis can cause severe illness characterized by severe respiratory failure, pulmonary hypertension, leucocytosis, and death. Over the past years, rising incidence rates of intensive care treatment in young infants were described. Due to several virulence factors (pertussis toxin, tracheal cytotoxin, adenylate cyclase toxin, filamentous hemagglutinin, and lipooligosaccharide) that promote bacterial adhesion and invasion, B. pertussis creates a unique niche for colonization within the human respiratory tract. The resulting long-term infection is mainly caused by the ability of B. pertussis to interfere with the host's innate and adaptive immune system. Although pertussis is a vaccine-preventable disease, it has persisted in vaccinated populations. Epidemiological data reported a worldwide increase in pertussis incidence among children during the past years. Either acellular pertussis (aP) vaccines or whole-cell vaccines are worldwide used. Recent studies did not detect any differences according to pertussis incidence when comparing the different vaccines used. Most of the currently used aP vaccines protect against acute infections for a period of 6-8 years. The resurgence of pertussis may be due to the lack of herd immunity caused by missing booster immunizations among adolescents and adults, low vaccine coverages in some geographic areas, and genetic changes of different B. pertussis strains. Due to the rising incidence of pertussis, probable solution strategies are discussed. Cocooning strategies (vaccination of close contact persons) and immunizations during pregnancy appear to be an approach to reduce neonatal contagiousness. During the past years, studies focused on the pathway of the immune modulation done by B. pertussis to provide a basis for the identification of new therapeutic targets to enhance the host's immune response and to probably modulate certain virulence factors.

Th1 versus Th2 T cell polarization by whole-cell and acellular childhood pertussis vaccines persists upon re-immunization in adolescence and adulthood

The recent increase in cases of whooping cough among teenagers in the US suggests that the acellular Bordetella pertussis vaccine (aP) that became standard in the mid 1990s might be relatively less effective than the whole-bacteria formulation (wP) previously used since the 1950s. To understand this effect, we compared antibody and T cell responses to a booster immunization in subjects who received either the wP or aP vaccine as their initial priming dose in childhood. Antibody responses in wP- and aP-primed donors were similar. Magnitude of T cell responses was higher in aP-primed individuals. Epitope mapping revealed the T cell immunodominance patterns were similar for both vaccines. Further comparison of the ratios of IFNγ and IL-5 revealed that IFNγ strongly dominates the T cell response in wP-primed donors, while IL-5 is dominant in aP primed individuals. Surprisingly, this differential pattern is maintained after booster vaccination, at times from eighteen years to several decades after the original aP/wP priming. These findings suggest that childhood aP versus wP vaccination induces functionally different T cell responses to pertussis that become fixed and are unchanged even upon boosting.

Epidemiological and Economic Effects of Priming With the Whole-Cell Bordetella pertussis Vaccine

IMPORTANCE

Current acellular pertussis vaccines may not protect against transmission of Bordetella pertussis.

OBJECTIVE

To assess whether a priming dose of whole-cell pertussis (wP) vaccine is cost-effective at reducing pertussis infection in infants.

DESIGN, SETTING, AND PARTICIPANTS

Mathematical model of pertussis transmission fit to US incidence data in a simulation of the US population. In this simulation study conducted from June 2014 to May 2015, the population was divided into 9 age groups corresponding to the current pertussis vaccination schedule and fit to 2012 pertussis incidence.

INTERVENTIONS

Inclusion of a priming dose of wP vaccine into the current acellular pertussis vaccination schedule.

MAIN OUTCOMES AND MEASURES

Reductions in symptomatic pertussis incidence by age group, increases in wP vaccine-related adverse effects, and quality-adjusted life-years owing to changing vaccine schedule.

RESULTS

Switching to a wP-priming vaccination strategy could reduce whooping cough incidence by up to 95% (95% CI, 91-98), including 96% (95% CI, 92-98) fewer infections in neonates. Although there may be an increase in the number of vaccine adverse effects, we nonetheless estimate a 95% reduction in quality-adjusted life-years lost with a switch to the combined strategy and a cost reduction of 94% (95% CI, 91-97), saving more than $142 million annually.

CONCLUSIONS AND RELEVANCE

Our results suggest that an alternative vaccination schedule including 1 dose of wP vaccine may be highly cost-effective and ethically preferred until next-generation pertussis vaccines become available.

The resurgence of mumps and pertussis

Vaccines and extended vaccination programs have had an extensive impact on morbidity and mortality rates due to infectious diseases. Because of the continuous and extensive use of vaccines in industrialized countries, many infectious diseases such as poliomyelitis, diphtheria and measles have been reduced to near-extinction. However, in recent years, many countries including the United States of America, the United Kingdom and Belgium, have been confronted with a resurgence of mumps and pertussis, despite high vaccination coverage for both vaccines. In this commentary, possible causes of this resurgence will be discussed, such as the occurrence of adapted microbes, failure to vaccinate and primary and secondary vaccine failure. Additional research of the immunological mechanisms is clearly needed to support the development of possible new and more immunogenic vaccines against mumps and pertussis. Meanwhile, extensive vaccination campaigns with both vaccines remain necessary.

Bordetella filamentous hemagglutinin and fimbriae: critical adhesins with unrealized vaccine potential

Pertussis, or whooping cough, is a highly contagious respiratory disease that is caused by the Gram-negative bacterium Bordetella pertussis, which is transmitted exclusively from human to human. While vaccination against B. pertussis has been successful, replacement of the whole cell vaccine with an acellular component vaccine has correlated with reemergence of the disease, especially in adolescents and infants. Based on their presumed importance in mediating adherence to host tissues, filamentous hemagglutinin (FHA) and fimbria (FIM) were selected as components of most acellular pertussis vaccines. In this review, we describe the biogenesis of FHA and FIM, recent data that show that these factors do, in fact, play critical roles in adherence to respiratory epithelium, and evidence that they also contribute to persistence in the lower respiratory tract by modulating the host immune response. We also discuss shortcomings of whole cell and acellular pertussis vaccines and the possibility that FHA and FIM could serve as effective protective antigens in next-generation vaccines.

Defining long-term drivers of pertussis resurgence, and optimal vaccine control strategies

Pertussis resurgence has been reported from several developed countries with long-standing immunisation programs. Among these, Australia in 2003 discontinued an 18 months (fourth) booster dose in favour of an adolescent (fifth) dose. We developed a model to evaluate determinants of resurgence in Australia and alternative vaccine strategies for mitigation. Novel characteristics of our model included the use of seroepidemiologic data for calibration, and broad investigation of variables relevant to transmission of, and protection against, pertussis. We simulated multiple parameter combinations, retaining those consistent with observed data for subsequent use in predictive models comparing alternative vaccination schedules. Reproducing the early control of pertussis followed by late resurgence observed in Australia required natural immunity to last decades longer than vaccine-acquired immunity, with mean duration exceeding 50 years in almost 90% of simulations. Replacement of the dose at 18 months with an adolescent dose in 2003 resulted in a 40% increase in infections in the age group 18-47 months by 2013. A six dose strategy (2, 4, 6, 18 months, 4 and 15 years) yielded a reduction in infection incidence (pre-school 43%, infants 8%) greater than any alternative strategies considered for timing of five administered doses. Our finding that natural immunity drives long-term trends in pertussis cycles is relevant to a range of pertussis strategies and provides the necessary context in which to consider maternal vaccination. Comparatively short-lived vaccine-acquired immunity requires multiple boosters over the first two decades of life to maximise reduction in infections.

T-cell immune responses to Bordetella pertussis infection and vaccination

The recent immunological investigations, stemming from the studies performed in the nineties within the clinical trials of the acellular pertussis vaccines, have highlighted the important role played by T-cell immunity to pertussis in humans. These studies largely confirmed earlier investigations in the murine respiratory infection models that humoral immunity alone is not sufficient to confer protection against Bordetella pertussis infection and that T-cell immunity is required. Over the last years, knowledge of T-cell immune response to B. pertussis has expanded broadly, taking advantage of the general progress in the understanding of anti-bacterial immunity and of refinements in methods to approach immunological investigations. In particular, experimental models of B. pertussis infection highlighted the cooperative role played by T-helper (Th)1 and Th17 cells for protection. Furthermore, the new baboon experimental model suggested a plausible explanation for the differences observed in the strength and persistence of protective immunity induced by the acellular or whole-cell pertussis vaccines and natural infection in humans, contributing to explain the upsurge of recent pertussis outbreaks. Despite the progress, open questions remain, the answer to them will possibly provide better tools to fight one of the hardest-to-control vaccine preventable disease.