Pertussis Across the Globe: Recent Epidemiologic Trends From 2000 to 2013

Predictors of maternal pertussis vaccination acceptance among pregnant women in Norway

Maternal vaccination against pertussis is safe and provides effective protection against pertussis for the newborn, but the vaccine coverage rate remains generally low. Norway is currently planning for introduction of routine maternal pertussis vaccination. To assess maternal pertussis vaccination acceptance among pregnant Norwegian women, we surveyed women at 20-40 weeks gestation in 2019. Among the 1,148 pregnant women participating in this cross-sectional study, 73.8% reported they would accept pertussis vaccination during pregnancy if it was recommended, 6.9% would not accept and 19.2% were undecided. Predictors for low likelihood of accepting pertussis vaccination during pregnancy included low confidence in health authorities and in maternal pertussis vaccination safety and effectiveness, low awareness and adherence to influenza vaccination during pregnancy, and low awareness of pertussis vaccination. The major reasons reported for not accepting or being undecided about maternal pertussis vaccination were lack of information on vaccine safety for both mother and child. Most women reported that they would consult their general practitioner or a midwife for information if they were offered maternal pertussis vaccination. General practitioners and midwives were also regarded as the most trustworthy sources of information if the women were in doubt about accepting vaccination. We conclude that information addressing safety concerns and raising awareness about maternal pertussis vaccination could increase acceptance of maternal pertussis vaccination. Our findings highlight the pivotal role of the antenatal and primary health care services in providing such information to pregnant women.

The current state of pertussis vaccination in pregnancy around the world, with recommendations for improved care: Consensus statements from the Global Pertussis Initiative

Bordetella pertussis, which causes a respiratory disease known as pertussis ("whooping cough") remains an important global challenge, with the incidence in pertussis cases increasing in recent years. Newborns and infants are at increased risk for severe morbidity and mortality from this bacterium. Vaccination in pregnancy has become an important strategy to both passively transfer immunity as well as prevent infection in pregnant persons, who are a major source of newborn infection, thus attempting to decrease the impact of this serious disease. It is considered safe for the pregnant person, the developing fetus, and the infant, and during the first 3 months of life it has been shown to be highly effective in preventing pertussis. There are a variety of strategies, recommendations, and adherence rates associated with pertussis vaccination in pregnancy around the world. We summarize the 2021 Global Pertussis Initiative Annual Meeting that reviewed the current global status of pertussis vaccination in pregnancy and remaining medical and scientific questions, with a focus on vaccination challenges and strategies for obstetric and gynecologic healthcare providers.

A multi-omics systems vaccinology resource to develop and test computational models of immunity

Systems vaccinology studies have identified factors affecting individual vaccine responses, but comparing these findings is challenging due to varying study designs. To address this lack of reproducibility, we established a community resource for comparing Bordetella pertussis booster responses and to host annual contests for predicting patients' vaccination outcomes. We report here on our experiences with the "dry-run" prediction contest. We found that, among 20+ models adopted from the literature, the most successful model predicting vaccination outcome was based on age alone. This confirms our concerns about the reproducibility of conclusions between different vaccinology studies. Further, we found that, for newly trained models, handling of baseline information on the target variables was crucial. Overall, multiple co-inertia analysis gave the best results of the tested modeling approaches. Our goal is to engage community in these prediction challenges by making data and models available and opening a public contest in August 2024.

Development of an algorithm for finding pertussis episodes in a population-based electronic health record database

While tetanus-diphtheria-acellular pertussis (Tdap) vaccines for adolescents and adults were licensed in 2005 and immunization strategies proposed, the burden of pertussis in this population remains under-recognized mainly due to atypical disease presentation, undermining efforts to optimize protection through vaccination. We developed a machine learning algorithm to identify undiagnosed/misdiagnosed pertussis episodes in patients diagnosed with acute respiratory disease (ARD) using signs, diseases and symptoms from clinician notes and demographic information within electronic health-care records (Optum Humedica repository [2007-2019]). We used two patient cohorts aged ≥11 years to develop the model: a positive pertussis cohort (4,515 episodes in 4,316 patients) and a negative pertussis (ARD) cohort (4,573,445 episodes and patients), defined using ICD 9/10 codes. To improve contrast between positive pertussis and negative pertussis (ARD) episodes, only episodes with ≥7 symptoms were selected. LightGBM was used as the machine learning model for pertussis episode identification. Model validity was determined using laboratory-confirmed pertussis positive and negative cohorts. Model explainability was obtained using the Shapley additive explanations method. The predictive performance was as follows: area under the precision-recall curve, 0.24 (SD, 7 × 10^-3); recall, 0.72 (SD, 4 × 10^-3); precision, 0.012 (SD, 1 × 10^-3); and specificity, 0.94 (SD, 7 × 10^-3). The model applied to laboratory-confirmed positive and negative pertussis episodes had a specificity of 0.846. Predictive probability for pertussis increased with presence of whooping cough, whoop, and post-tussive vomiting in clinician notes, but decreased with gastrointestinal bleeding, sepsis, pulmonary symptoms, and fever. In conclusion, machine learning can help identify pertussis episodes among those diagnosed with ARD.

Combined regulation of pro-inflammatory cytokines production by STAT3 and STAT5 in a model of B. pertussis infection of alveolar macrophages

Bordetella pertussis is a highly contagious respiratory pathogen responsible for whooping-cough or pertussis. Despite high vaccination coverage worldwide, this gram-negative bacterium continues to spread among the population. B. pertussis is transmitted by aerosol droplets from an infected individual to a new host and will colonize its upper respiratory tract. Alveolar macrophages (AMs) are effector cells of the innate immune system that phagocytose B. pertussis and secrete both pro-inflammatory and antimicrobial mediators in the lungs. However, understanding their role in B. pertussis pathogenesis at the molecular level is hampered by the limited number of primary AMs that can be collected in vivo. In order to decipher the regulation of innate response induced by B. pertussis infection, we used for the first time self-renewing, non-transformed cells, called Max Planck Institute (MPI) cells, which are phenotypically and functionally very close to pulmonary AMs. Using optimized infection conditions, we characterized the entry and the clearance of B. pertussis within MPI macrophages. We showed that under these conditions, MPI cells exhibit a pro-inflammatory phenotype with the production of TNF, IL-1β, IL-6 and MIP-2α, similarly to primary AMs purified from broncho-alveolar fluids of mice. In addition, we explored the yet uncharacterized role of the signal transduction activator of transcription (STAT) proteins family in the innate immune response to B. pertussis infection and showed for the first time the parallel regulation of pro-inflammatory cytokines by STAT3 and STAT5 in MPI macrophages infected by B. pertussis. Altogether, this work highlights the interest of using MPI cells for experiments optimization and preliminary data acquisition to understand B. pertussis interaction with AMs, and thus significantly reduce the number of animals to be sacrificed.

Impact of maternal whole-cell or acellular pertussis primary immunization on neonatal immune response

With the introduction of pertussis immunization for pregnant women in many countries, there has been renewed interest in the impact of whole-cell pertussis vaccine (wP) versus acellular vaccine (aP) on disease control, particularly regarding the best approach for priming. To gather evidence on this topic, we analyzed the impact of aP or wP priming on aP vaccination during pregnancy (aPpreg) in mice. Two-mother vaccination schemes were employed (wP-wP-aPpreg and aP-aP-aPpreg), and the immune response in the mothers and their offspring, as well as the protection of the offspring against Bordetella pertussis challenge, were assessed. Pertussis toxin (PTx)-specific IgG responses were detected in mothers after both the second and third doses, with higher titers after the third dose, regardless of the vaccination schedule. However, a significant reduction in PTx-IgG levels was observed after 22 weeks post aPpreg immunization in mothers with the aP-aP-aPpreg scheme but not in the wP-wP-aPpreg immunized mothers. The aP-aP-aPpreg schedule triggered a murine antibody response mainly to a Th2-profile, while wP-wP-aPpreg induced a Th1/Th2 mixed profile. Both immunization schemes administered to the mothers protected the offspring against pertussis, but the wP-wP-aPpreg vaccination conferred offspring protection in all pregnancies at least up to 20 weeks after receiving the aPpreg-dose. In contrast, the immunity induced by aP-aP-aPpreg began to decline in births that occurred 18 weeks after receiving the aPpreg dose. For the aP-aP-aPpreg scheme, pups born from gestations furthest from aPpreg (+22 weeks) had lower PTx-specific IgG levels than those born closer to the application of the dose during pregnancy. In contrast, for pups born to wP-wP-aPpreg vaccinated mothers, the PTx-specific IgG levels were maintained over time, even for those born at the longest time studied (+22 weeks). It is noteworthy that only the pups born from mothers with aP-aP-aPpreg and receiving a neonatal dose of either aP or wP were more susceptible to B. pertussis infection than mice with only maternal immunity, suggesting interference with the induced immunity (p<0.05). However, it should be noted that mice with maternal immunity, whether vaccinated or not with neonatal doses, are better protected against colonization with B. pertussis than mice without maternal immunity but vaccinated with aP or wP.

Impact of pregnancy on polyfunctional IgG and memory B cell responses to Tdap immunization

BACKGROUND

Maternal pertussis immunization using Tdap vaccine is recommended in many countries to protect newborns from severe post-natal infection. Immunological changes during pregnancy may influence the response to vaccines. The quality of IgG and memory B cell responses to Tdap immunization in pregnant women has not yet been described.

METHODS

The impact of pregnancy on the response to Tdap vaccination was assessed by comparing humoral immune responses in 42 pregnant and 39 non-pregnant women. The levels of serum pertussis antigens and tetanus toxoid-specific IgG, IgG subclasses, IgG Fc-mediated effector functions, as well as memory B cell frequencies were assessed before and at several time points after vaccination.

RESULTS

Tdap immunization induced similar levels of pertussis and tetanus-specific IgG and IgG subclasses in pregnant and non-pregnant women. Pregnant women produced IgG promoting complement deposition, and neutrophils and macrophages phagocytosis at levels comparable to non-pregnant women. They were also able to expand pertussis and tetanus-specific memory B cells at similar frequencies as non-pregnant women, suggesting equivalent "boostability". Higher levels of vaccine-specific IgG, IgG subclasses, and IgG Fc-mediated effector functions were detected in cord blood as compared to maternal blood, indicating efficient transport across the placenta.

CONCLUSIONS

This study demonstrates that pregnancy does not affect the quality of effector IgG and memory B cell responses to Tdap immunization and that polyfunctional IgG are efficiently transferred across the placenta.

REGISTRY'S URL AND THE TRIAL'S REGISTRATION NUMBER

ClinicalTrials.Gov (NCT03519373).

Evaluation of serum anti-pertussis toxin IgA antibodies for the diagnosis of Bordetella pertussis infection in young children

BACKGROUND

The determination of serum anti-pertussis toxin (PT) IgG antibodies is recommended for the diagnosis and surveillance of pertussis. However, the diagnostic power of anti-PT IgG can be hampered by possible interference from previous vaccinations. We aim to assess if anti-PT IgA antibodies can be well induced by Bordetella pertussis (B. pertussis) infections in children, and their capacity to improve pertussis serodiagnosis.

METHODS

Serum samples from 172 hospitalized children younger than 10 years old with confirmed pertussis were tested. Pertussis was confirmed by culture, PCR and/or serology. Anti-PT IgA antibodies were determined with commercial ELISA kits.

RESULTS

Sixty-four (37.2 %) subjects had anti-PT IgA antibodies greater than or equal to 15 IU/ml, and 52 (30.2 %) of them had anti-PT IgA antibodies greater than or equal to 20 IU/ml. No children with negative anti-PT IgG (less than 40 IU/ml) were observed to have anti-PT IgA antibodies greater than or equal to 15 IU/ml. Of patients younger than one year of age, about 50 % had an IgA antibody response. Moreover, the proportion of subjects with anti-PT IgA antibodies greater than or equal to 15 IU/ml among PCR negative subjects was significantly higher than that among PCR positive subjects (76.9 % vs 35.5 %).

CONCLUSIONS

The determination of anti-PT IgA antibodies does not seem to have added value for the serodiagnosis of pertussis in children older than one year of age. However, for infants, determination of serum anti-PT IgA antibodies appears to be useful for the diagnosis of pertussis especially when PCR and culture are negative. The results should be interpreted with caution as the number of subjects included in this study was limited.

US Infant Pertussis Incidence Trends Before and After Implementation of the Maternal Tetanus, Diphtheria, and Pertussis Vaccine

Importance

Infants younger than 1 year have the highest burden of pertussis morbidity and mortality. In 2011, the US introduced tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination during pregnancy to protect infants before vaccinations begin.

Objective

To assess the association of maternal Tdap vaccination during pregnancy with the incidence of pertussis among infants in the US.

Design, Setting, and Participants

In this ecologic study, a time-trend analysis was performed of infant pertussis cases reported through the National Notifiable Diseases Surveillance System between January 1, 2000, and December 31, 2019, in the US. Statistical analysis was performed from April 1, 2020, to October 31, 2022.

Exposures

Maternal Tdap vaccination during pregnancy.

Main Outcomes and Measures

Pertussis incidence rates were calculated and compared between 2 periods-the pre-maternal Tdap vaccination period (2000-2010) and the post-maternal Tdap vaccination period (2012-2019)-for 2 age groups: infants younger than 2 months (target group of maternal vaccination) and infants aged 6 months to less than 12 months (comparison group). Incidence rate differences between the 2 age groups were modeled using weighted segmented linear regression. The slope difference between the 2 periods was estimated to assess the association of maternal Tdap vaccination with pertussis incidence among infants.

Results

A total of 57 460 pertussis cases were reported in infants younger than 1 year between 2000 and 2019; 19 322 cases (33.6%) were in infants younger than 2 months. During the pre-maternal Tdap vaccination period, annual pertussis incidence did not change among infants younger than 2 months (slope, 3.29 per 100 000 infants per year; P = .28) but increased slightly among infants aged 6 months to less than 12 months (slope, 2.10 per 100 000 infants per year; P = .01). There was no change in the difference in incidence between the 2 age groups (slope, 0.08 per 100 000 infants per year; P = .97) during the pre-maternal Tdap vaccination period overall. However, in the post-maternal Tdap vaccination period, incidence decreased among infants younger than 2 months (slope, -14.53 per 100 000 infants per year; P = .001) while remaining unchanged among infants aged 6 months to less than 12 months (slope, 1.42 per 100 000 infants per year; P = .29). The incidence rate difference between the 2 age groups significantly decreased during the post-maternal Tdap vaccination period (slope, -14.43 per 100 000 infants per year; P < .001). Pertussis incidence rate differences were significantly different between the pre-maternal and post-maternal Tdap vaccination periods (slope difference, -14.51 per 100 000 infants per year; P = .01).

Conclusions and Relevance

In this study, following maternal Tdap vaccine introduction, a sustained decrease in pertussis incidence was observed among infants younger than 2 months, narrowing the incidence gap with infants aged 6 months to less than 12 months. These findings suggest that maternal Tdap vaccination is associated with a reduction in pertussis burden in the target age group (<2 months) and that further increases in coverage may be associated with additional reductions in infant disease.

Distinct early cellular kinetics in participants protected against colonization upon Bordetella pertussis challenge

BACKGROUNDTo date, only limited data are available on the mechanisms of protection against colonization with Bordetella pertussis in humans.METHODSIn this study, the cellular responses to B. pertussis challenge were monitored longitudinally using high-dimensional EuroFlow-based flow cytometry, allowing quantitative detection of more than 250 different immune cell subsets in the blood of 15 healthy donors.RESULTSParticipants who were protected against colonization showed different early cellular responses compared with colonized participants. Especially prominent for colonization-protected participants were the early expansion of CD36- nonclassical monocytes on day 1 (D1), natural killer cells (D3), follicular T helper cells (D1-D3), and plasma cells (D3). Plasma cell expansion on D3 correlated negatively with the CFU load on D7 and D9 after challenge. Increased plasma cell maturation on D11-D14 was found in participants with seroconversion.CONCLUSIONThese early cellular immune responses following experimental infection can now be further characterized and potentially linked to an efficient mucosal immune response, preventing colonization. Ultimately, their presence may be used to evaluate whether new B. pertussis vaccine candidates are protective against B. pertussis colonization, e.g., by bacterial challenge after vaccination.TRIAL REGISTRATIONClinicalTrials.gov NCT03751514.FUNDINGInnovative Medicines Initiative 2 Joint Undertaking and the EuroFlow Consortium.

Assessment of Pertussis Underreporting in Italy

A study was conducted to assess the degree of pertussis underreporting in Italy. An analysis was performed to compare the frequency of pertussis infections estimated using seroprevalence data with the pertussis incidence based on reported cases among the Italian population. For this purpose, the proportion of subjects who had an anti-PT ≥ 100 IU/mL (indicative of B. pertussis infection within the last 12 months) was compared with the reported incidence rate among the Italian population ≥5 years old, divided into two age groups (6-14 and ≥15 years old), obtained from the European Centre for Disease Prevention and Control (ECDC) database. The pertussis incidence rate in the Italian population ≥5 years old reported by the ECDC in 2018 was 6.75/100,000 in the 5-14 age group and 0.28/100,000 in the ≥15 age group. The proportion of subjects recruited in the present study with an anti-PT ≥ 100 IU/mL was 0.95% in the 6-14 age group and 0.97% in the ≥15 age group. The estimated rate of pertussis infections based on seroprevalence was approximately 141-fold and 3452-fold higher than the reported incidence in the 6-14 age group and in the ≥15 age group, respectively. Quantification of underreporting can allow for the burden of pertussis, as well as the impact of ongoing vaccination, to be better evaluated.

Vaccination against pertussis in Latin American preterm and low-birth weight infants: experts opinion position for a neglected childhood age group

BACKGROUND

Pertussis remains as one of the oldest leading vaccine-preventable diseases of childhood, despite many decades of primary vaccine doses' and boosters' implementation. Although the epidemiology is well understood in infants and children, premature babies and low-birth weight infants remain a special group where the disease incidence is unknown, severity of the disease is considerable, and specific vaccination recommendations are scarce.

RESEARCH DESIGN AND METHODS

A retrospective review of the available evidence of pertussis vaccination in premature and low birth weight infants was analyzed from January 2000 to December 2022 in six selected countries: Argentina, Mexico, Colombia, Panamá, Costa Rica, and Chile.

RESULTS

Chile had reports of adverse effects associated with vaccination of premature infants with the pentavalent vaccine, and their rationale to switching to the hexavalent vaccine. Colombia had reports of the justification for the use of hexavalent vaccine in prematures in the Neonatal Units and Kangaroo Mother Programs throughout the country. Mexico had selected publications of the vaccination status in prematures and low-birth weight infants.

CONCLUSION

Despite its importance, increased morbidity, and highest risk of complications in premature babies, there is a paucity of information of vaccine recommendations and coverage rates among selected Latin American infants.

Evaluation of Whole-Cell and Acellular Pertussis Vaccines in the Context of Long-Term Herd Immunity

After the pertussis vaccine had been introduced in the 1940s and was shown to be very successful in reducing the morbidity and mortality associated with the disease, the possibility of improving both vaccine composition and vaccination schedules has become the subject of continuous interest. As a result, we are witnessing a considerable heterogeneity in pertussis vaccination policies, which remains beyond universal consensus. Many pertussis-related deaths still occur in low- and middle-income countries; however, these deaths are attributable to gaps in vaccination coverage and limited access to healthcare in these countries, rather than to the poor efficacy of the first generation of pertussis vaccine consisting in inactivated and detoxified whole cell pathogen (wP). In many, particularly high-income countries, a switch was made in the 1990s to the use of acellular pertussis (aP) vaccine, to reduce the rate of post-vaccination adverse events and thereby achieve a higher percentage of children vaccinated. However the epidemiological data collected over the past few decades, even in those high-income countries, show an increase in pertussis prevalence and morbidity rates, triggering a wide-ranging debate on the causes of pertussis resurgence and the effectiveness of current pertussis prevention strategies, as well as on the efficacy of available pertussis vaccines and immunization schedules. The current article presents a systematic review of scientific reports on the evaluation of the use of whole-cell and acellular pertussis vaccines, in the context of long-term immunity and vaccines efficacy.

Sero-Epidemiological Study of Bordetella pertussis Infection in the Italian General Population

A multicenter study was conducted to estimate the prevalence of pertussis IgG antibodies (anti-PTx) in the Italian population. Serum samples (4154) collected in the years 2019−2020 from subjects aged 6 to 90 years were tested. The anti-PTx IgG levels were determined by ELISA test. The limit of detection was 5 IU/mL (International Units per milliliter); values ≥ 40 IU/mL and ≥100 IU/mL indicate an infection that has occurred in recent years and a recent infection (occurred during the last year), respectively. The mean concentration of anti-PTx IgG antibodies in the tested samples was 13 IU/mL; 1.0% of subjects had a titer ≥ 100 IU/mL, 5.3% a titer between 40 and 100 IU/mL, and 38.9% a titer < 5 IU/mL. The mean antibody concentration was significantly higher in males than in females. The age group 25−39 years had the lowest percentage of negative subjects (36.9%) and the highest prevalence of subjects with antibody titers ≥ 100 IU/mL (1.3%). In the age group ≥ 65 years, the prevalence of subjects with titers between 40 and 100 IU/mL (6.7%) and the percentage of negative subjects (44.8%) was higher than in the other age groups. The results highlight the possible role of adolescents and adults in the transmission of B. pertussis.

Vaccination in Pregnancy against Pertussis: A Consensus Statement on Behalf of the Global Pertussis Initiative

Infants are at high risk for severe morbidity and mortality from pertussis disease during early infancy. Vaccination against pertussis in pregnancy has emerged as the ideal strategy to protect infants during these early, vulnerable, first months of life. On 30 November and 1 December 2021, the Global Pertussis Initiative held a meeting that aimed to discuss and review the most up-to-date scientific literature supporting vaccination against pertussis in pregnancy and outstanding scientific questions. Herein, we review the current and historically published literature and summarize the findings as consensus statements on vaccination against pertussis in pregnancy on behalf of the Global Pertussis Initiative.

The whole-cell pertussis vaccine imposes a broad effector B cell response in mouse heterologous prime-boost settings

ÍSince the introduction of new generation pertussis vaccines, resurgence of pertussis has been observed in many developed countries. Former whole-cell pertussis (wP) vaccines are able to protect against disease and transmission but have been replaced in several industrialized countries because of their reactogenicity and adverse effects. Current acellular pertussis (aP) vaccines, made of purified proteins of Bordetella pertussis, are efficient at preventing disease but fail to induce long-term protection from infection. While the systemic and mucosal T cell immunity induced by the 2 types of vaccines has been well described, much less is known concerning B cell responses. Taking advantage of an inducible activation-induced cytidine deaminase fate-mapping mouse model, we compared effector and memory B cells induced by the 2 classes of vaccines and showed that a stronger and broader memory B cell and plasma cell response was achieved by a wP prime. We also observed that homologous or heterologous vaccine combinations that include at least 1 wP administration, even as a booster dose, were sufficient to induce this broad effector response, thus highlighting its dominant imprint on the B cell profile. Finally, we describe the settlement of memory B cell populations in the lung following subcutaneous wP prime vaccination.

Genome Characteristic of Bordetella parapertussis Isolated from Iran

Pertussis also known as whooping cough is a respiratory infection in humans particularly with severe symptoms in infants and usually caused by Bordetella pertussis. However, Bordetella parapertussis can also cause a similar clinical syndrome. During 2012 to 2015, from nasal swabs sent from different provinces to the pertussis reference laboratory of Pasture Institute of Iran for pertussis confirmation, seven B. parapertussis isolates were identified by bacterial culture, biochemical tests, and the presence of IS1001 insertion in the genome. The expression of pertactin (Prn) as one the major virulence factor for bacterial adhesion was investigated using western blot. Moreover, the genomic characteristic of one recently collected isolate, IRBP134, from a seven-month infant was investigated using Illumina NextSeq sequencing protocol. The results revealed the genome with G+C content 65% and genome size 4.7 Mbp. A total of 81 single nucleotide polymorphisms and 13 short insertions and deletions were found in the genome compared to the B. parapertussis 12822 as a reference genome showing ongoing evolutionary changes. A phylogeny relationship of IRBP134 was also investigated using global B. parapertussis available genomes.

Association Between Real-time Polymerase Chain Reaction Cycle Threshold Value and Clinical Severity in Neonates and Infants Infected With Bordetella pertussis

BACKGROUND

Polymerase chain reaction (PCR) is highly sensitive and is thus the standard method for diagnosing pertussis. Real-time PCR is widely used because of its accuracy and the simplicity of the simultaneous cycle threshold (Ct) value, which represents the copy numbers of the target gene. Little is known of the association of Ct value with pertussis severity in neonates and infants.

METHODS

This study determined Ct values in neonates and infants diagnosed with pertussis by real-time PCR using nasopharyngeal samples at Vietnam National Children's Hospital in Hanoi in 2017 and 2019. The association of disease severity and clinical parameters were analyzed using univariate and multivariate analyses.

RESULTS

We evaluated 108 patients with pertussis [median age: 63 days, interquartile range (IQR): 41-92 days]. Only 6/108 (6%) received at least 1 dose of a pertussis-containing vaccine. Among them, 24 (22.2%) had severe disease requiring care in a pediatric intensive care unit, 16 (13.8%) required mechanical ventilation, and 3 (2.6%) died. The median Ct value was lower in patients with severe disease (19.0, IQR: 16.5-22.0, n = 24) than in those without severe disease (25.5, IQR: 20.0-30.0, n = 84) (P = 0.002). Logistic regression analyses demonstrated that PCR Ct value [odds ratio (OR): 1.783, 95% confidence interval (CI): 1.013-3.138, P = 0.045], age (OR: 3.118, 95% CI: 1.643-5.920, P = 0.001), and white blood cell counts (OR: 0.446, 95% CI: 0.261-0.763, P = 0.003) remained significantly associated with severe disease.

CONCLUSIONS

Real-time PCR Ct values for pertussis might be useful as a predictor of severe disease in neonates and infants.

Pertussis surveillance results from a French general practitioner network, France, 2017 to 2020

Introduction

In France, three complementary surveillance networks involving hospitals and paediatrician practices currently allow pertussis surveillance among infants (<1 year old) and children (1–12 years old). Data on incidences among adolescents (13–17 years old) and adults (≥ 18 years) are scarce. In 2017, a sentinel surveillance system called Sentinelles network, was implemented among general practitioners (GPs).

Aim

The purpose of Sentinelles network is to assess pertussis incidence, monitor the cases’ age distribution and evaluate the impact of the country’s vaccination policy. We present the results from the first 4 years of this surveillance.

Methods

GPs of the French Sentinelles network reported weekly numbers of epidemiologically or laboratory-confirmed cases and their characteristics.

Results

A total of 132 cases were reported over 2017–2020. Estimated national incidence rates per 100,000 inhabitants were 17 (95% confidence interval (CI): 12–22) in 2017, 10 (95% CI: 6–14) in 2018, 15 (95% CI: 10–20) in 2019 and three (95% CI: 1–5) in 2020. The incidence rate was significantly lower in 2020 than in 2017–2019. Women were significantly more affected than men (83/132; 63% of women, p = 0.004); 66% (87/132) of cases were aged 15 years or over (median age: 31.5 years; range: 2 months–87 years). Among 37 vaccinated cases with data, 33 had received the recommended number of doses for their age.

Conclusions

These results concur with incidences reported in other European countries, and with studies showing that the incidences of several respiratory diseases decreased in 2020 during the COVID-19 pandemic. The results also suggest a shift of morbidity towards older age groups, and a rapid waning of immunity after vaccination, justifying to continue this surveillance.

Experts' Opinion for Improving Pertussis Vaccination Rates in Adolescents and Adults: A Call to Action

This article highlights the importance of diphtheria-tetanus-acellular pertussis (with reduced antigen content, dTap) vaccination in preventing pertussis, a respiratory infection that is still widespread and easily transmitted. In particular, it highlights the need to receive a booster vaccination throughout life to maintain high antibody levels, which decrease through time. This document collects the opinions that emerged from the comparison between major Italian experts in the field of vaccination. This working group was created to promote a "call to action", aimed at raising awareness among all institutions, public health authorities, and health workers involved in the vaccination process, about the importance of dTap vaccine administration and with the mindset of implementing the strategic vaccination plan provided by the National Vaccine Plan (NVP). In fact, despite this vaccine being included in the NVP, there are some issues attributable to the practice of vaccination (local health authorities, vaccination centers, occupational health services, gynecology centers, societies of work). Therefore, it is necessary that the Ministry defines the vaccination coverage objectives, identifies the groups of subjects who should receive the booster vaccine (subjects exposed to greater risk of infection, subjects over 60, pregnant women), and applies all the necessary measures to encourage the implementation of this practice.

The Mechanism of Pertussis Cough Revealed by the Mouse-Coughing Model

Pertussis, also known as whooping cough, is a contagious respiratory disease caused by the Gram-negative bacterium Bordetella pertussis. This disease is characterized by severe and uncontrollable coughing, which imposes a significant burden on patients. However, its etiological agent and the mechanism are totally unknown because of a lack of versatile animal models that reproduce the cough. Here, we present a mouse model that reproduces coughing after intranasal inoculation with the bacterium or its components and demonstrate that lipooligosaccharide (LOS), pertussis toxin (PTx), and Vag8 of the bacterium cooperatively function to cause coughing. Bradykinin induced by LOS sensitized a transient receptor potential ion channel, TRPV1, which acts as a sensor to evoke the cough reflex. Vag8 further increased bradykinin levels by inhibiting the C1 esterase inhibitor, the major downregulator of the contact system, which generates bradykinin. PTx inhibits intrinsic negative regulation systems for TRPV1 through the inactivation of G_i GTPases. Our findings provide a basis to answer long-standing questions on the pathophysiology of pertussis cough.

BCG-induced trained immunity enhances acellular pertussis vaccination responses in an explorative randomized clinical trial

Acellular pertussis (aP) booster vaccines are central to pertussis immunization programs, although their effectiveness varies. The Bacille Calmette-Guérin (BCG) vaccine is a prototype inducer of trained immunity, which enhances immune responses to subsequent infections or vaccinations. While previous clinical studies have demonstrated that trained immunity can protect against heterologous infections, its effect on aP vaccines in humans is unknown. We conducted a clinical study in order to determine the immunological effects of trained immunity on pertussis vaccination. Healthy female volunteers were randomly assigned to either receive BCG followed by a booster dose of tetanus-diphteria-pertussis inactivated polio vaccine (Tdap-IPV) 3 months later (BCG-trained), BCG + Tdap-IPV concurrently, or Tdap-IPV followed by BCG 3 months later. Primary outcomes were pertussis-specific humoral, T- and B-cell responses and were quantified at baseline of Tdap-IPV vaccination and 2 weeks thereafter. As a secondary outcome in the BCG-trained cohort, ex vivo leukocyte responses were measured in response to unrelated stimuli before and after BCG vaccination. BCG vaccination 3 months prior to, but not concurrent with, Tdap-IPV improves pertussis-specific Th1-cell and humoral responses, and also increases total memory B cell responses. These responses were correlated with enhanced IL-6 and IL-1β production at the baseline of Tdap-IPV vaccination in the BCG-trained cohort. Our study demonstrates that prior BCG vaccination potentiates immune responses to pertussis vaccines and that biomarkers of trained immunity are the most reliable correlates of those responses.

Reduced Bordetella pertussis-specific CD4+ T-Cell Responses at Older Age

Pertussis, a human-specific respiratory infectious disease caused by the Gram-negative bacterium Bordetella pertussis (Bp), remains endemic with epidemic years despite high vaccination coverage. Whereas pertussis vaccines and natural infection with Bp confer immune protection, the duration of protection varies and is not lifelong. Recent evidence indicates a considerable underestimation of the pertussis burden among older adults. Whereas the impact of increasing age on Bp-specific humoral immunity has been demonstrated, little is known on immunosenescence of CD4⁺ T-cell responses in the context of Bp. Here, we aimed to address whether increasing age impacts responsiveness of the Bp-specific CD4⁺ T-cells in the memory pool following a clinically symptomatic pertussis infection in whole cell vaccine-primed pediatric and adult cases. Cytokine and proliferative responses and phenotypical profiles of CD4⁺ T cells specific for Bp antigens at an early and late convalescent timepoint were compared. Responses of various Th cytokines, including IFNγ, were significantly lower in older adults at early and late timepoints post diagnosis. In addition, we found lower frequencies of Bp-specific proliferated CD4⁺ T cells in older adults, in the absence of differences in replication profile. Phenotyping of Bp-specific CD4⁺ T cells suggested reduced expression of activation markers rather than increased expression of co-inhibitory markers. Altogether, our findings show that the magnitude and functionality of the Bp-specific memory CD4⁺ T-cell pool decrease at older age. Declined CD4⁺ T-cell responsiveness to Bp is suggested to contribute to the burden of pertussis in older adults.

Age and Primary Vaccination Background Influence the Plasma Cell Response to Pertussis Booster Vaccination

Pertussis is a vaccine-preventable disease caused by the bacterium Bordetella pertussis. Over the past years, the incidence and mortality of pertussis increased significantly. A possible cause is the switch from whole-cell to acellular pertussis vaccines, although other factors may also contribute. Here, we applied high-dimensional flow cytometry to investigate changes in B cells in individuals of different ages and distinct priming backgrounds upon administration of an acellular pertussis booster vaccine. Participants were divided over four age cohorts. We compared longitudinal kinetics within each cohort and between the different cohorts. Changes in the B-cell compartment were correlated to numbers of vaccine-specific B- and plasma cells and serum Ig levels. Expansion and maturation of plasma cells 7 days postvaccination was the most prominent cellular change in all age groups and was most pronounced for more mature IgG1+ plasma cells. Plasma cell responses were stronger in individuals primed with whole-cell vaccine than in individuals primed with acellular vaccine. Moreover, IgG1+ and IgA1+ plasma cell expansion correlated with FHA-, Prn-, or PT- specific serum IgG or IgA levels. Our study indicates plasma cells as a potential early cellular marker of an immune response and contributes to understanding differences in immune responses between age groups and primary vaccination backgrounds.

Risk factors and prediction model of severe pertussis in infants < 12 months of age in Tianjin, China

Background

To identify risk factors associated with the prognosis of pertussis in infants (< 12 months).

Methods

A retrospective study on infants hospitalized with pertussis January 2017 to June 2019. The infants were divided into two groups according to the severity of disease: severe pertussis and non-severe pertussis groups. We collected all case data from medical records including socio-demographics, clinical manifestations, and auxiliary examinations. Univariate analysis and Logistic regression were used.

Results

Finally, a total of 84 infants with severe pertussis and 586 infants with non-severe pertussis were admitted. The data of 75% of the cases (severe pertussis group, n = 63; non-severe pertussis group, n = 189) were randomly selected for univariate and multivariate logistic regression analysis. The results showed rural area [P = 0.002, OR = 6.831, 95% CI (2.013–23.175)], hospital stay (days) [P = 0.002, OR = 1.304, 95% CI (1.107–1.536)], fever [P = 0.040, OR = 2.965, 95% CI (1.050–8.375)], cyanosis [P = 0.008, OR = 3.799, 95% CI (1.419–10.174)], pulmonary rales [P = 0.021, OR = 4.022, 95% CI (1.228–13.168)], breathing heavily [P = 0.001, OR = 58.811, 95% CI (5.503–628.507)] and abnormal liver function [P < 0.001, OR = 9.164, 95% CI (2.840–29.565)] were independent risk factors, and higher birth weight [P = 0.006, OR = 0.380, 95% CI (0.191–0.755)] was protective factor for severe pertussis in infants. The sensitivity and specificity of logistic regression model for remaining 25% data of severe group and common group were 76.2% and 81.0%, respectively, and the consistency rate was 79.8%.

Conclusions

The findings indicated risk factor prediction models may be useful for the early identification of severe pertussis in infants.

Epidemiology of pertussis in Costa Rica and the impact of vaccination: A 58-year experience (1961-2018)

Costa Rica is an upper middle-income country in Central America with a vigorous public health system. We have studied the number of cases, hospitalizations, and deaths due to pertussis from 1961 to 2018, in relation to vaccine coverage. Following the introduction of the fourth and fifth doses of DTP (booster doses) in 1973 there was a marked reduction of reported pertussis. In 2002 pertussis surveillance and laboratory diagnosis were improved. In 2007, Tdap post-partum immunization was introduced and then switched to intrapartum Tdap immunization in 2011. Of these two strategies post-partum vaccination seemed to have a greater effect in decreasing hospitalizations and deaths, nevertheless, since 2011 there has been only 4 infant deaths due to pertussis.

Diphtheria-tetanus-pertussis vaccine: past, current & future

The diphtheria-tetanus-pertussis (DTP) vaccine can prevent diphtheria, tetanus and pertussis. The component antigens of the DTP vaccine had long been monovalent vaccines. The pertussis vaccine was licensed in 1914. The same year, the mixtures of diphtheria toxin and antitoxin were put into use. In 1926, alum-precipitated diphtheria toxoid was registered, and in 1937 adsorbed tetanus toxoid was put on the market. The development of numerous effective DTP vaccines quickly stimulated efforts to combine DTP with other routine vaccines for infants. This overview covers the most important information regarding the invention of DTP vaccines, their modifications and the needs that should be focused on in the future.

Differences between influenza and pertussis vaccination uptake in pregnancy: a multi-center survey study in Italy

BACKGROUND

A suboptimal maternal vaccination coverage in 2017-18 has been reported in Italy. The study aims were to (i) assess changes in maternal influenza and tetanus, diphtheria and acellular pertussis vaccination coverage during 2018-19 influenza season compared to the previous season (ii) estimate influenza vaccine coverage among maternal care providers (MCPs) and (iii) explore the characteristics of vaccine delivery to pregnant women.

METHODS

We conducted a cross-sectional survey among pregnant women and MCPs about influenza and pertussis immunization during pregnancy. We also collected information regarding prenatal care characteristics and vaccine delivery among four centers in Italy.

RESULTS

We recruited 483 pregnant women and 452 MCPs. The influenza and pertussis vaccine uptake among pregnant women for the season 2018-19 was 14.9% and 60.9%, respectively. MCPs' influenza vaccine uptake was 33.6%. Knowing that the flu vaccine was safe for mothers and their infants and being vaccinated in the previous influenza season were associated with higher vaccine uptake. Regarding pertussis, being a housewife was associated to lower vaccine uptake, while knowing the vaccine is effective and safe for mothers and newborns were associated with higher pertussis vaccine uptake. The single most important factor associated to higher coverage of both influenza and pertussis vaccines was receiving a health-care provider's vaccine advice. Most pregnant women (69.4%) stated that they preferred to be vaccinated in their same prenatal care setting.

CONCLUSIONS

Receiving a health-care provider's vaccine advice and the availability of vaccines during prenatal care visits might improve vaccination coverage among pregnant women.

Real-life requests for Bordetella polymerase chain reaction testing in children presenting to hospital

From 2015 to 2017, 3197 interpretable Bordetella polymerase chain reaction (PCR) tests were performed for 2760 children presenting to our tertiary university hospital. Requests mainly came from the emergency department (62%) and for children older than 1 year (68%). Only 32 PCR (1%) results were positive, mainly in children younger than 1 year (n = 29/32, 90.6%; p<0.001). When focusing on the PCR indications in 2017, we found the requests were mainly based on nonspecific respiratory symptoms and were clinically unjustified in 383 cases (39%). Pediatricians overused Bordetella PCR in clinical practice. They should reserve their requests for cases of young children with symptoms suggestive of respiratory illness and/or incomplete pertussis immunization.

Whether Urbanization Has Intensified the Spread of Infectious Diseases-Renewed Question by the COVID-19 Pandemic

The outbreak of the COVID-19 epidemic has triggered adiscussion of the relationship between urbanization and the spread of infectious diseases. Namely, whether urbanization will exacerbate the spread of infectious diseases. Based on 31 provincial data from 2002 to 2018 in China, the impact of urbanization on the spread of infectious diseases from the dimensions of "population" and "land" is analyzed in this paper by using the GMM (generalized method of moments) model. The empirical study shows that the population increase brought by urbanization does not aggravate the spread of infectious diseases. On the contrary, urban education, employment and entrepreneurship, housing, medical and health care, and other basic public services brought by population urbanization can help reduce the risk of the spread of infectious diseases. The increasing density of buildings caused by land urbanization increases the risk of the spread of infectious diseases. Moreover, the impact of urbanization on the spread of infectious diseases has regional heterogeneity. Therefore, the prevention and control of disease play a crucial role.

A phase 2 randomized controlled dose-ranging trial of recombinant pertussis booster vaccines containing genetically inactivated pertussis toxin in women of childbearing age

•

Recombinant inactivated pertussis vaccines are safe in non-pregnant women.

•

Lower-dose genetically-inactivated pertussis toxin has comparable immunogenicity.

•

Monovalent recombinant pertussis vaccine shows favorable immunogenicity and safety.

Background

A phase 2 randomized-controlled safety and immunogenicity trial evaluating different doses of recombinant acellular pertussis vaccine containing genetically-inactivated pertussis toxin (PT_gen) was conducted in women of childbearing age in Thailand to identify formulations to advance to a trial in pregnant women.

Methods

A total of 250 women were randomized 1:1:1:1:1 to receive one dose of one of three investigational vaccines including low-dose recombinant pertussis-only vaccine containing 1 μg PT_gen and 1 μg FHA (ap1_gen), tetanus, reduced-dose diphtheria (Td) combined to ap1_gen (Tdap1_gen) or combined to recombinant pertussis containing 2 μg PT_gen and 5 μg FHA (Tdap2_gen), or one dose of licensed recombinant TdaP vaccine containing 5 μg PT_gen and 5 μg FHA (Boostagen®, TdaP5_gen) or licensed Tdap vaccine containing 8 μg of chemically inactivated pertussis toxoid (PT_chem), 8 μg FHA, and 2.5 μg pertactin (PRN) (Boostrix^TM, Tdap8_chem). Serum Immunoglobulin G (IgG) antibodies against vaccine antigens were measured before and 28 days after vaccination by ELISA. To advance to a trial in pregnant women, formulations had to induce a PT-IgG seroresponse rate with a 95% confidence interval (95% CI) lower limit of ≥ 50%.

Results

Between 5 and 22 July 2018, a total of 250 women with median age of 31 years were enrolled. Post-vaccination PT-IgG seroresponse rates were 92% (95% CI 81–98) for ap1_gen, 88% (95% CI 76–95) for Tdap1_gen, 80% (95% CI 66–90) for Tdap2_gen, 94% (95% CI 83–99) for TdaP5_gen, and 78% (95% CI 64–88) for Tdap8_chem. Frequencies of injection site and systemic reactions were comparable between the groups. No serious adverse events were reported during the 28-day post-vaccination period.

Conclusions

All recombinant acellular pertussis vaccines were safe and immunogenic in women of childbearing age, and all met pre-defined immunogenicity criteria to advance to a trial in pregnant women.

Clinical Trial Registration: Thai Clinical Trial Registry, TCTR20180321004.

Evaluation of Outer Membrane Vesicles Obtained from Predominant Local Isolate of Boredetella pertussis as a Vaccine Candidate

Background:

Pertussis is a current contagious bacterial disease caused by Bp. Given the prevalence of pertussis, development of new vaccines is important. This study was attempted to evaluate the expression of main virulence factors (PTX, PRN, and FHA) from Bp predominant strains and also compare the expression of these factors in the OMVs obtained from predominant circulating Bp isolate.

Methods:

The physicochemical features of the prepared OMVs were analyzed by electron microscopy and SDS-PAGE. The presence of the mentioned virulence factors was confirmed by Western blotting. BALB/c mice (n = 21) immunized with characterized OMVs were challenged intranasally with sublethal doses of Bp, to examine their protective capacity.

Results:

Electron microscopic examination of the OMVs indicated vesicles within the range of 40 to 200 nm. SDS-PAGE and Western blotting demonstrated the expression of all three main protective immunogens (PTX, PRN, and FHA), prevalent in the predominant, challenge, and vaccine strains, and OMVs of the predominant IR37 strain and BP134 vaccine strain. Significant differences were observed in lung bacterial counts between the immunized mice with OMV (30 CFU/lung) compared to the negative control group ((6 10⁴ CFU/lung; p < 0.001). In mice immunized with OMVs (3 µg), the number of lungs recovered colonies after five days dropped at least five orders of magnitude compared to the control group.

Conclusion:

OMVs obtained from circulating isolates with the predominant profile may constitute a highly promising vaccine quality. They also can be proposed as a potential basic material for the development of new pertussis vaccine candidate.

Identification of BvgA-Dependent and BvgA-Independent Small RNAs (sRNAs) in Bordetella pertussis Using the Prokaryotic sRNA Prediction Toolkit ANNOgesic

Noncoding small RNAs (sRNAs) are crucial for the posttranscriptional regulation of gene expression in all organisms and are known to be involved in the regulation of bacterial virulence. In the human pathogen Bordetella pertussis, which causes whooping cough, virulence is controlled primarily by the master two-component system BvgA (response regulator)/BvgS (sensor kinase). In this system, BvgA is phosphorylated (Bvg⁺ mode) or nonphosphorylated (Bvg^- mode), with global transcriptional differences between the two. B. pertussis also carries the bacterial sRNA chaperone Hfq, which has previously been shown to be required for virulence. Here, we conducted transcriptomic analyses to identify possible B. pertussis sRNAs and to determine their BvgAS dependence using transcriptome sequencing (RNA-seq) and the prokaryotic sRNA prediction program ANNOgesic. We identified 143 possible candidates (25 Bvg⁺ mode specific and 53 Bvg^- mode specific), of which 90 were previously unreported. Northern blot analyses confirmed all of the 10 ANNOgesic candidates that we tested. Homology searches demonstrated that 9 of the confirmed sRNAs are highly conserved among B. pertussis, Bordetella parapertussis, and Bordetella bronchiseptica, with one that also has homologues in other species of the Alcaligenaceae family. Using coimmunoprecipitation with a B. pertussis FLAG-tagged Hfq, we demonstrated that 3 of the sRNAs interact directly with Hfq, which is the first identification of sRNA binding to B. pertussis Hfq. Our study demonstrates that ANNOgesic is a highly useful tool for the identification of sRNAs in this system and that its combination with molecular techniques is a successful way to identify various BvgAS-dependent and Hfq-binding sRNAs. IMPORTANCE Noncoding small RNAs (sRNAs) are crucial for posttranscriptional regulation of gene expression in all organisms and are known to be involved in the regulation of bacterial virulence. We have investigated the presence of sRNAs in the obligate human pathogen B. pertussis, using transcriptome sequencing (RNA-seq) and the recently developed prokaryotic sRNA search program ANNOgesic. This analysis has identified 143 sRNA candidates (90 previously unreported). We have classified their dependence on the B. pertussis two-component system required for virulence, namely, BvgAS, based on their expression in the presence/absence of the phosphorylated response regulator BvgA, confirmed several by Northern analyses, and demonstrated that 3 bind directly to B. pertussis Hfq, the RNA chaperone involved in mediating sRNA effects. Our study demonstrates the utility of combining RNA-seq, ANNOgesic, and molecular techniques to identify various BvgAS-dependent and Hfq-binding sRNAs, which may unveil the roles of sRNAs in pertussis pathogenesis.

Lessons from a mature acellular pertussis vaccination program and strategies to overcome suboptimal vaccine effectiveness

INTRODUCTION

Despite high vaccination coverage among children and adolescents, pertussis remains a public health problem, with large outbreaks occurring periodically in the US and other developed countries.

AREAS COVERED

We examine lessons learned more than 20 years after implementation of programs which use only acellular pertussis vaccines and propose avenues for possible effective use of acellular pertussis vaccine to prevent large outbreaks.

EXPERT OPINION

Acellular pertussis vaccines were introduced more than 20 years ago, yet the incidence of pertussis has been increasing over the past decade, with periodic large outbreaks marked by notable shifts in disease burden from infants and young children toward fully vaccinated adolescents and young adults. This age shift is mainly driven by the waning of vaccine immunity. To better protect adolescents against pertussis, modification of the current acellular pertussis vaccination schedule or adoption of new vaccination strategies should be considered. For infants not yet eligible to be vaccinated, maternal vaccination against pertussis during pregnancy is an effective way to protect infants from infection, severe disease and death. Implementation of maternal vaccination programs should be encouraged in countries without one or efforts to improve coverage should be supported in countries with existing program.

Modification of innate immune responses to Bordetella pertussis in babies from pertussis vaccinated pregnancies

BACKGROUND

Tetanus, diphtheria, acellular pertussis, inactivated polio (Tdap-IPV) vaccines administered during pregnancy protect young infants from Bordetella pertussis (B. pertussis) infection. Whilst the impact of maternal Tdap-IPV vaccination on infants' humoral response to subsequent pertussis immunisation has been investigated, little is known about any impact on innate responses.

METHODS

We investigated the immune response to B. pertussis in mothers and infants from Tdap-IPV-vaccinated and unvaccinated pregnancies, utilising a whole blood assay and flow cytometric phenotyping of neonatal natural killer (NK) cells, monocytes and dendritic cells. Blood was collected from mother and umbilical cord at birth, and from infants at seven weeks (one week pre-primary pertussis immunisation) and five months of age (one month post-primary pertussis immunisation). 21 mothers and 67 infants were studied.

FINDINGS

Vaccinated women had elevated pro-inflammatory cytokine responses to B. pertussis. At birth, babies of vaccinated women had elevated IL-2 and IL-12 responses, elevated classical monocyte proportions, and reduced monocyte and NK cell cytokine responses. The elevated IL-2 response persisted to seven weeks-of-age, when lower IL-10 and IL-13 responses were also seen. One-month post-primary pertussis vaccination, infants from vaccinated pregnancies still had lower IL-10 responses to B. pertussis, as well as lower IL-4.

INTERPRETATION

This study suggests that pertussis vaccination during pregnancy impacts infant cellular immune responses, potentially contributing to the modification of antibody responses already reported following primary immunisation against B. pertussis.

FUNDING

National Institute for Health Research Imperial Biomedical Research Centre and IMmunising PRegnant women and INfants neTwork (funded by the GCRF Networks in Vaccines R&D).

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.

Epidemiology of Pertussis in Individuals of All Ages Hospitalized With Respiratory Illness in South Africa, January 2013-December 2018

BACKGROUND

Policy recommendations on pertussis vaccination need to be guided by data, which are limited from low- and middle-income countries. We aimed to describe the epidemiology of pertussis in South Africa, a country with high human immunodeficiency virus (HIV) prevalence and routine pertussis vaccination for 6 decades including the acellular vaccine since 2009.

METHODS

Hospitalized patients of all ages were enrolled at 5 sentinel sites as part of a pneumonia surveillance program from January 2013 through December 2018. Nasopharyngeal specimens and induced sputum were tested by polymerase chain reaction (PCR) for Bordetella pertussis. In addition, demographic and clinical information were collected. Incidence rates were calculated for 2013-2016, and multivariable logistic regression performed to identify factors associated with pertussis.

RESULTS

Over the 6-year period 19 429 individuals were enrolled, of which 239 (1.2%) tested positive for B. pertussis. Detection rate was highest in infants aged <6 months (2.8%, 155/5524). Mean annual incidence was 17 cases per 100 000 population, with the highest incidence in children <1 year of age (228 per 100 000). Age-adjusted incidence was 65.9 per 100 000 in HIV-infected individuals compared to 8.5 per 100 000 in HIV-uninfected individuals (risk ratio 30.4, 95% confidence interval: 23.0-40.2). Ten individuals (4.2%) with pertussis died; of which 7 were infants aged <6 months and 3 were immunocompromised adults.

CONCLUSIONS

Pertussis continues to be a significant cause of illness and hospitalization in South Africa, despite routine vaccination. The highest burden of disease and death occurred in infants; however, HIV-infected adults were also identified as an important group at risk of B. pertussis infection.

The impact of pertussis in infants: insights from a hospital-based enhanced surveillance system, Lazio region, Italy, 2016 to 2019

Background

Routine surveillance systems for pertussis often suffer from under-recognition and under-reporting.

Aim

Our aim was to describe the epidemiology and the clinical features of pertussis in children younger than 1 year in an Italian region, detected through an enhanced hospital surveillance system.

Methods

From 2016 to 2019, we monitored the incidence and the clinical characteristics of hospitalised pertussis cases younger than 1 year in two paediatric hospitals involved in the PERTINENT project.

Results

We detected 141 pertussis cases, corresponding to an estimated incidence of 105.8 per 100.000 in 2016, 91.7 per 100.000 in 2017, 64.5 per 100.000 in 2018 and 40.9 per 100.000 in 2019, based on the hospitals’ catchment area, roughly corresponding to the Lazio region. A total of 101 cases (77.1%) had a household member with cough or other respiratory symptoms. The most frequent combination of symptoms was paroxysmal cough with apnoea in the absence of fever. Almost 40% had been prescribed an antibiotic treatment before hospitalisation, and the median time from symptom onset to contact with the hospital was 8 days. Thirty-one (22.0%) had complications.

Conclusion

An enhanced surveillance system showed a high incidence of pertussis among infants in the Lazio region, where the impact of this disease may still be underestimated. Increasing the coverage of pertussis immunisation among pregnant women and improving the capacity for early detection in primary care may contribute to reducing the impact of pertussis among infants.

Prevention of chronic diseases in middle-age women: a cross-sectional study on an Italian large sample

BACKGROUND

The age around 50 years represents a crucial point for women: menopause leads to biological changes and it begins breast and colon-rectal cancer screening. This study aimed at assessing frequencies of cardiovascular risk factors and analyzing participation in screening and vaccination.

METHODS

In 2017, a cross-sectional study was performed in Northern Italy. Totally, 12 249 women, aged between 50 and 54 years, were enrolled by General Practitioners (GPs). It was used a 21-item form, with information about: socio-demographic, anamnestic and clinical data, execution of a booster shot of tetanus-diphtheria-acellular pertussis (Tdap) vaccine in the last decade and of PAP-test, mammography and faecal occult blood test in the last 2 years. Descriptive and crosstab χ2 analyses were performed with STATA MP13. The significance level was P ≤ 0.05.

RESULTS

Our findings showed the presence of cardiovascular risk factors, such as obesity (10.95%), hypertension (13.76%), hyperlipidaemia (11.57%), glycaemia ≥ 100 mg dl-1 (16.97%), poor physical activity (73.49%), smoking (18.28%), cardiovascular family history (FH) (51.70%). There were a lower participation in colo-rectal cancer screening (45.09%) compared with breast (85.06%) and cervical (77.16%) cancer screening and an insufficient Tdap booster dose compliance (17.56%). Chi-square analyses showed correlations between cardiovascular FH and body mass index, hypertension, hyperlipidaemia, glycaemia and smoking, and between cancer FH and participation in breast and colo-rectal cancer screening (P < 0.05).

CONCLUSIONS

Women with cardiovascular disease FH represent a priority target of educational interventions considering the prevalence of concomitant risk factors. Programmes aimed at increasing screening and vaccination participation should be implemented.

Highly Sensitive Flow Cytometry Allows Monitoring of Changes in Circulating Immune Cells in Blood After Tdap Booster Vaccination

Antigen-specific serum immunoglobulin (Ag-specific Ig) levels are broadly used as correlates of protection. However, in several disease and vaccination models these fail to predict immunity. In these models, in-depth knowledge of cellular processes associated with protective versus poor responses may bring added value. We applied high-throughput multicolor flow cytometry to track over-time changes in circulating immune cells in 10 individuals following pertussis booster vaccination (Tdap, Boostrix®, GlaxoSmithKline). Next, we applied correlation network analysis to extensively investigate how changes in individual cell populations correlate with each other and with Ag-specific Ig levels. We further determined the most informative cell subsets and analysis time points for future studies. Expansion and maturation of total IgG1 plasma cells, which peaked at day 7 post-vaccination, was the most prominent cellular change. Although these cells preceded the increase in Ag-specific serum Ig levels, they did not correlate with the increase of Ig levels. In contrast, strong correlation was observed between Ag-specific IgGs and maximum expansion of total IgG1 and IgA1 memory B cells at days 7 to 28. Changes in circulating T cells were limited, implying the need for a more sensitive approach. Early changes in innate immune cells, i.e. expansion of neutrophils, and expansion and maturation of monocytes up to day 5, most likely reflected their responses to local damage and adjuvant. Here we show that simultaneous monitoring of multiple circulating immune subsets in blood by flow cytometry is feasible. B cells seem to be the best candidates for vaccine monitoring.

Incidence and severity of pertussis hospitalisations in infants aged less than 1 year in 37 hospitals of six EU/EEA countries, results of PERTINENT sentinel pilot surveillance system, December 2015 to December 2018

Introduction

PERTINENT is a pilot active surveillance system of infants hospitalised with pertussis in six European Union/European Economic Area countries (37 hospitals, seven sites).

Aim

This observational study aimed to estimate annual pertussis incidence per site from 2016 to 2018 and respective trends between 2017 and 2018. Pertussis cases were described, including their severity.

Methods

We developed a generic protocol and laboratory guidelines to harmonise practices across sites. Cases were hospitalised infants testing positive for Bordetella pertussis by PCR or culture. Sites collected demographic, clinical, laboratory data, vaccination status, and risk/protective factors. We estimated sites’ annual incidences by dividing case numbers by the catchment populations.

Results

From December 2015 to December 2018, we identified 469 cases (247 males; 53%). The median age, birthweight and gestational age were 2.5 months (range: 0–11.6; interquartile range (IQR): 2.5), 3,280 g (range: 700–4,925; IQR: 720) and 39 weeks (range: 25–42; IQR: 2), respectively. Thirty cases (6%) had atypical presentation either with cough or cyanosis only or with absence of pertussis-like symptoms. Of 330 cases with information, 83 (25%) were admitted to intensive care units including five deceased infants too young to be vaccinated. Incidence rate ratios between 2018 and 2017 were 1.43 in Czech Republic (p = 0.468), 0.25 in Catalonia (p = 0.002), 0.71 in France (p = 0.034), 0.14 in Ireland (p = 0.002), 0.63 in Italy (p = 0.053), 0.21 in Navarra (p = 0.148) and zero in Norway.

Conclusions

Incidence appeared to decrease between 2017 and 2018 in all but one site. Enhanced surveillance of hospitalised pertussis in Europe is essential to monitor pertussis epidemiology and disease burden.

Expression of Bordetella pertussis Antigens Fused to Different Vectors and Their Effectiveness as Vaccines

Pertussis is an acute respiratory tract infection caused by Bordetella pertussis. Even though its current vaccine coverage is relatively broad, they still have some shortcomings such as short protection time and might be incapable of blocking the spread of the disease. In this study, we developed new pertussis vaccine candidates by separately fusing three pertussis antigens (B. pertussis fimbriae 2 “Fim2”, pertussis toxin S1 subunit “PtxS1”, and filamentous hemagglutinin “FHA_1877–2250”) to each of two immune-boosting carrier proteins (B subunits of AB5 toxin family: cholera toxin B subunit “CTB” and shiga toxin B subunit “StxB”). We then immunized mice with these fusion antigens and found that they significantly increased the serum antibody titers and elicited high bactericidal activity against B. pertussis. After CTB-or StxB-fused antigen-immunized mice were challenged with a non-lethal dose of B. pertussis, the bacterial loads in different tissues of these mice were significantly reduced, and their lung damage was nearly invisible. Furthermore, we also demonstrated that these candidate vaccines could provide strong prophylactic effects against a lethal challenge with B. pertussis. Overall, our candidate vaccines conferred better immune protection to mice compared with pertussis antigen alone. This B5 subunit-based vaccine strategy provides a promising option for vaccine design.

Obstetric and perinatal health outcomes after pertussis vaccination during pregnancy in Ontario, Canada: a retrospective cohort study

BACKGROUND

In February 2018, Canada's National Advisory Committee on Immunization recommended maternal vaccination with tetanus-diphtheria-acellular pertussis (Tdap) vaccine during pregnancy to prevent severe pertussis infection in young infants. This study assessed the relation between maternal Tdap vaccination and obstetric and perinatal outcomes in Ontario.

METHODS

We performed a population-based cohort study of all births from April 2012 to March 2017 using multiple linked health administrative databases. We used Cox regression with a time-dependent exposure variable to estimate adjusted hazard ratios (HRs) for preterm birth (< 37 wk), very preterm birth (< 32 wk) and stillbirth. We assessed remaining outcomes (gestational hypertension, chorioamnionitis, postpartum hemorrhage, severe postpartum hemorrhage, being small for gestational age, neonatal intensive care unit stay > 24 h, composite neonatal morbidity) using log-binomial regression to generate adjusted risk ratios (RRs). We adjusted estimates for potential confounding using propensity score weighting.

RESULTS

Of 615 213 infants (live births and stillbirths), 11 519 were exposed to Tdap vaccination in utero. There was no increased risk for preterm birth (adjusted HR 0.98, 95% confidence interval [CI] 0.91-1.06), very preterm birth (adjusted HR 1.10, 95% CI 0.86-1.41), stillbirth (adjusted HR 1.15, 95% CI 0.82-1.60) or being small for gestational age (adjusted RR 0.96, 95% CI 0.90-1.02). The risks of a neonatal intensive care unit stay exceeding 24 hours (adjusted RR 0.82, 95% CI 0.76-0.88) and neonatal morbidity (adjusted RR 0.81, 95% CI 0.75-0.87) were decreased. There was no association with chorioamnionitis (adjusted RR 1.17, 95% CI 0.99-1.39), postpartum hemorrhage (adjusted RR 1.01, 95% CI 0.91-1.13) or severe postpartum hemorrhage (adjusted RR 0.79, 95% CI 0.55-1.13), but we observed a reduced risk of gestational hypertension (adjusted RR 0.87, 95% CI 0.78-0.96).

INTERPRETATION

Our results complement evidence that maternal Tdap vaccination is not associated with adverse outcomes in mothers or infants. Ongoing evaluation in Canada is needed as maternal Tdap vaccination coverage increases in coming years.

Is there a potential for novel, nasal pertussis vaccines?

INTRODUCTION

Pertussis, caused by Bordetella pertussis, remains a major public health problem, despite high vaccination coverage. Furthermore, the disease incidence has increased recently, especially in countries that have switched from whole-cell to acellular pertussis vaccines.

AREAS COVERED

Here, we provide a state-of-the art summary of the reasons for the pertussis resurgence and discuss potential solutions using current vaccines and challenges for the development of novel vaccines. PubMed was searched for publications with the terms pertussis and vaccines. Many new vaccine candidates are proposed but most have not reached clinical development. Most of them induce strong systemic immune responses and protection in mice. However, since B. pertussis is a mucosal pathogen, albeit with systemic effects, local immunity may be crucial to prevent B. pertussis infection and transmission. Recent efforts have focused on vaccine candidates able to induce immunity in the nasal cavity, and one of them is currently in clinical development.

EXPERT COMMENTARY

New pertussis vaccines are needed to durably control the disease and circulation of B. pertussis. A major challenge is to prove efficacy against disease in randomized controlled trials, while it is feasible to provide evidence for prevention of infection, since asymptomatic carriage of B. pertussis is wide spread.

Pertussis in early life: underdiagnosed, severe, and risky disease. A seven-year experience in a pediatric tertiary-care hospital

AIM

Pertussis continues to be a common worldwide infection in pediatric and adult populations.We aimed to study epidemiological and clinical characteristics of infants and children admitted for pertussis to a tertiary-care hospital and to investigate the risk factors for pediatric intensive care unit (PICU) admission.

MATERIALS AND METHODS

With a retrospective study, we analyzed all medical reports of patients admitted to Bambino Gesù Children's Hospital in Rome from January 2011 to December 2018 with a diagnosis of pertussis.

RESULTS

We examined 195 patients. The majority of hospitalized children (66.15%) were <3 months of age. No mother had received pertussis containing vaccine during pregnancy. Ten cases required admission in PICU. The age at admission was lower in PICU patients with respect to ward patients (42.8 vs 240 days; p < .0007), length of hospital stay was longer in PICU group (24.7 vs 7.52 days; p < .003). Patients who needed PICU admission had greater white blood cell count at hospital admission compared with those hospitalized in the pediatric ward. One infant died and one had encephalitis.

CONCLUSIONS

Pertussis is a remerging disease. In infants, it is associated with significant morbidity and mortality. In recent years, many countries have implemented different vaccination strategies and public health measures to prevent the increase in pertussis cases. Maternal vaccination has been shown to be highly protective for infants <3 months of age before they can develop their own immunity via vaccination.

Emerging macrolide resistance in Bordetella pertussis in mainland China: Findings and warning from the global pertussis initiative

Whooping cough, or pertussis, is a highly communicable infectious disease caused by the bacterium Bordetella pertussis. Vaccination once reduced the incidence of the disease, but a global resurgence of the infection happened during the past two decades, likely due to the waning immunity of vaccination. Macrolides such as erythromycin and azithromycin are the drugs of primary choice for treatment. In this personal view, we call for attention to macrolide-resistant B. pertussis (MRBP), which has emerged and prevailed in mainland China for years and are exclusively mediated by mutations in the 23S rRNA gene. Whether the prevalence of MRBP in China results from overuse of azithromycin in clinical medicine remains unknown. The incidence of MRBP is low in other countries, but this could be a technical illusion since China employs culture as the mainstream diagnostic method whereas nucleic-acid amplification test being widely used in other countries fail to test antimicrobial susceptibility. Given the increasingly frequent global travel that facilitates microbial transmission worldwide, there is a pressing need to perform international surveillance on MRBP to prevent the potential circulation of the organism. Finding alternative agents that possess good activity against B. pertussis is also urgently required.

Effect of Macrolides and β-lactams on Clearance of Bordetella pertussis in the Nasopharynx in Children With Whooping Cough

OBJECTIVE

The purpose of the current study is to investigate the bactericidal effect of macrolides and β-lactams on Bordetella pertussis (B. pertussis) in the nasopharynx and provide guidance for treating macrolides-resistant B. pertussis infections.

METHODS

Patients with whooping cough was diagnosed by culture of nasopharynx swabs between January 2016 to December 2018. B. pertussis was identified using specific antisera against pertussis and parapertussis. Drug susceptibility test was carried out using the E-test method. The clearance of B. pertussis in nasopharynx at 7 and 14 days into and posttreatment with macrolides, and β-lactams was compared.

RESULTS

A total of 125 B. pertussis samples were collected from patients who received single antibiotic treatment. Among those isolates, 62.4% (78/125) had high resistance with minimum inhibitory concentrations greater than 256 mg/L for erythromycin and azithromycin. The MIC90 of piperacillin, cefoperazone-sulbactam, meropenem, ampicillin, ceftriaxone, ceftazidime and trimethoprim-sulfamethoxazole for these isolates was <0.016, 0.094, 0.094, 0.19, 0.19, 0.25 and 0.75 mg/L, respectively. The clearance rate with β-lactams treatment (68.8%, 44/64) was significantly higher than that with macrolides treatment at 14 days posttreatment (50.8%, 31/61) (χ2 = 4.18, P = 0.04). Macrolides had a better clearance rate at 7 days posttreatment than β-lactams (χ2 = 4.49, P = 0.03) for macrolides-sensitive isolates and a worse clearance rate for macrolides-resistant isolates.

CONCLUSION

B. pertussis isolates had a high-resistant rate for macrolides in our study. Macrolides are the first choice for treating pertussis caused by macrolides-sensitive strains, and some β-lactams such as piperacillin should be considered as alternative antibiotics for treatment of macrolides-resistant B. pertussis infection.

Impact of Tdap vaccine during pregnancy on the incidence of pertussis in children under one year in Brazil - A time series analysis

Pertussis is a globally distributed infectious disease that is a significant cause of morbidity and mortality, especially in infants who are too young to be immunized. This disease is common in childhood, and when it occurs during the first few months of life, it leads to hospitalization and, sometimes, death. Brazil has adopted the strategy of maternal immunization against pertussis in late 2014. This study aims to analyze public data on the disease to determine whether there was an impact on the disease burden following the introduction of the vaccine Tdap in pregnant women and its magnitude. We performed a time-series analysis of the incidence of pertussis between October 2010 and January 2019. We stratified the population of interest into three groups: infants aged less than two months old, infants aged two to six months, and infants aged six months to one year, according to Brazil's vaccination schedule. We found a protective effect of maternal vaccination in all age groups, more prominent on the first group. Before the intervention, infants under two months had a higher risk of getting pertussis in comparison with infants two to six months old (HR 1.15, CI 95%: 1.11-1.19). After the intervention, age under two months is a protective factor compared with two to six months (HR 0.90, CI 95%: 0.82-0.98). The pertussis incidence reduced in all age groups and all Brazil's Regions.

Effect of a postpartum prescription for pertussis vaccine: a before-and-after study

BACKGROUND

Among the strategies to encourage pregnant women to be vaccinated against pertussis in the postpartum period, that of giving them a prescription has been evaluated only sparsely.

OBJECTIVE

To measure the effect of giving women who are not immunized against pertussis a prescription for the vaccine at discharge from the maternity unit.

MATERIAL AND METHODS

Single-center before-and-after study (2011: before; 2015: after). All women received both oral and written information about vaccination against pertussis. During the after period, they were also specifically asked their immunization status during pregnancy. Those currently unimmunized received a written prescription for it at discharge.

RESULTS

Among the women unimmunized at delivery, the percentage who were vaccinated postpartum climbed from 17 to 42% between 2011 and 2015 (p < 0.001), while the percentage of their unimmunized partners who were vaccinated remained stable (27 and 29%, p = 0.74). During this time, the percentage of women immunized against pertussis at the beginning of pregnancy rose from 32 to 52% (p < 0.001). Finally, the percentage of all women protected against this disease postpartum climbed from 44 to 72% between these two periods (p < 0.001).

CONCLUSIONS

In the postpartum period, giving a prescription for pertussis vaccine to women unimmunized is accompanied by a significant elevation in their vaccination rate. Nevertheless, this rate remains low and better strategies have to be implemented.

Immunological Distinctions between Acellular and Whole-Cell Pertussis Immunizations of Baboons Persist for at Least One Year after Acellular Vaccine Boosting

While both whole-cell (wP) and acellular pertussis (aP) vaccines have been highly effective at reducing the global pertussis disease burden, there are concerns that compared to wP vaccination, the immune responses to aP vaccination may wane more rapidly. To gain insights into the vaccine elicited immune responses, pre-adult baboons were immunized with either aP or wP vaccines, boosted with an aP vaccine, and observed over a nearly two-year period. Priming with a wP vaccine elicited a more Th17-biased response than priming with aP, whereas priming with an aP vaccine led to a more Th2-biased response than priming with wP. These differences were maintained after aP vaccine boost immunizations. Compared to aP, animals primed with a wP vaccine exhibited greater numbers of pertussis specific memory B cells. While aP and wP vaccine priming initially elicited similar levels of anti-pertussis toxin antibody, titers declined more rapidly in aP vaccine primed animals leading to a 4-fold difference. Both wP and aP vaccine immunization could induce serum bactericidal activity (SBA); however, only one wP vaccine immunization was required to elicit SBA while multiple aP vaccine immunizations were required to elicit lower, less durable SBA titers. In conclusion, when compared to aP vaccine, priming with wP vaccine elicits distinct cellular and humoral immune responses that persist after aP vaccine boosting.