Coverage rates for diphtheria, tetanus, poliomyelitis, and pertussis age-specific booster recommendations in France: 2018 update of the real-world cohort analysis.

The French National Immunization Program was updated in 2013 for vaccination against diphtheria, tetanus, pertussis, and poliomyelitis. Our previous findings on the evolution of age-specific booster vaccination coverage rates (VCRs) up to 2017 suggested suboptimal vaccination coverages due to the pre-2013 recommendation-residual vaccination practices. In the current analysis, we evaluated all age-specific booster VCR and distribution of age at vaccination visits in 2018. In this retrospective observational cohort study, the cumulative booster VCRs were updated at all vaccination visits up to 2018 among the people who were eligible for a booster vaccination, using a 1/97th random sample of French national healthcare reimbursement databases. The cumulative booster VCR for individuals from all age groups increased from 2017 to 2018, except for 85-years-old vaccination visit. Majority of the individuals from all age groups were vaccinated (boosted) with a vaccine containing the pertussis valence. In 2018, sharp peaks corresponding to the recommended ages for booster vaccination visits were observed for individuals aged 6, 11 to 13, 25, 45, and 65 years. Our study reiterates suboptimal coverages in France and implies the need for booster vaccination throughout life for the protection of the population.

Cocooning strategy: Pertussis vaccination coverage rate of parents with a new-born in 2016 and 2017 in France.

Background: The "cocooning" strategy was introduced in 2004 to protect infants too young to be vaccinated against pertussis, by immunizing their parents and close relatives. The study objective was to assess its implementation 12 years after its introduction by estimating the pertussis vaccination coverage rates (VCR) among parents of newborns. Materials and methods: Pertussis VCR were estimated among all women who gave birth and men who took paternity leave, in 2016 or 2017, from a 1/97th random sample of French claims data. Two distinct study periods were defined based on current recommendations for the cocooning strategy: the "common practice" and the "parental project" periods. Results: In 2016, the pertussis VCR of women having given birth and men having taken paternity leave was 47.2 and 47.1%, respectively (46.1 and 45.6% in 2017, respectively). About one quarter of vaccinations were performed during the "parental project" period, with the vaccine most frequently reimbursed during the month of childbirth for women (57.1% in 2016 and 49.4% in 2017) and before or during the month the paternity leave began for men (about 78% in both 2016 and 2017). General practitioners were the main prescribers in private practice, even during the "parental project" period. Conclusion: To optimize the protection for infants, the main objective of the cocooning strategy, pertussis immunization coverage of adults and seniors needs to be improved. Moreover, cocooning vaccination linked to a parental project needs to be performed earlier, during pregnancy (for those around the mother) or in immediate post-partum (e.g., during the maternity stay).

Can vaccines control bacterial virulence and pathogenicity? Bordetella pertussis: the advantage of fitness over virulence.

Some vaccines, such as diphtheria toxoid and acellular pertussis vaccines (aPVs), may favor the emergence of less pathogenic strains of the respective bacteria they target. This review discusses the impact of the wide use of aPV on Bordetella pertussis phenotype evolutions and their beneficial consequences in the light of the diphtheria toxoid immunization program experience and structuring evidence review in a causal analysis following Bradford Hill's causality criteria. All aPVs contain the pertussis toxin (PT), the main virulence factor of B.pertussis, alone or with one adhesin (filamentous hemagglutinin (FHA)), two adhesins (FHA and pertactin (PRN)) or four adhesins (FHA, PRN and two fimbriae (Fim 2/3)). In countries where the coverage of aPVs containing PRN is high, PRN negative B.pertussis isolates are increasing in prevalence, but isolates nonproducing the other antigens are rarely reported. We hypothesize that the selective pressure at play with PRN should exist against all aVP antigens, although detection biases may hinder its detection for other antigens, especially PT. PT being responsible for clinically frank cases of the disease, the opportunity to collect PT negative isolates is far lower than to collect PRN negative isolates which have a limited clinical impact. The replacement of the current B.pertussis by far less pathogenic isolates no longer producing the factors contained in aPVs should be expected as a consequence of the wide aPV use.

Association between the COVID-19 pandemic and pertussis derived from multiple nationwide data sources, France, 2013 to 2020.

BackgroundInterventions to mitigate the COVID-19 pandemic may impact other respiratory diseases.AimsWe aimed to study the course of pertussis in France over an 8-year period including the beginning of the COVID-19 pandemic and its association with COVID-19 mitigation strategies, using multiple nationwide data sources and regression models.MethodsWe analysed the number of French pertussis cases between 2013 and 2020, using PCR test results from nationwide outpatient laboratories (Source 1) and a network of the paediatric wards from 41 hospitals (Source 2). We also used reports of a national primary care paediatric network (Source 3). We conducted a quasi-experimental interrupted time series analysis, relying on negative binomial regression models. The models accounted for seasonality, long-term cycles and secular trend, and included a binary variable for the first national lockdown (start 16 March 2020).ResultsWe identified 19,039 pertussis cases from these data sources. Pertussis cases decreased significantly following the implementation of mitigation measures, with adjusted incidence rate ratios of 0.10 (95% CI: 0.04-0.26) and 0.22 (95% CI: 0.07-0.66) for Source 1 and Source 2, respectively. The association was confirmed in Source 3 with a median of, respectively, one (IQR: 0-2) and 0 cases (IQR: 0-0) per month before and after lockdown (p = 0.0048).ConclusionsThe strong reduction in outpatient and hospitalised pertussis cases suggests an impact of COVID-19 mitigation measures on pertussis epidemiology. Pertussis vaccination recommendations should be followed carefully, and disease monitoring should be continued to detect any resurgence after relaxation of mitigation measures.

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

IntroductionIn 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).AimThe 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.MethodsGPs of the French Sentinelles network reported weekly numbers of epidemiologically or laboratory-confirmed cases and their characteristics.ResultsA 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.ConclusionsThese 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.

Hospital-based prospective study of pertussis in infants and close contacts in Tehran, Iran.

BACKGROUND: Pertussis remain a global health concern, especially in infants too young to initiate their vaccination. Effective vaccination and high coverage limit the circulation of the pathogen, yet duration of protection is limited and boosters are recommended during a lifetime. In Iran, boosters are given at 18 months and 6 years old using whole pertussis vaccines for which efficacy is not known, and pertussis surveillance is scant with only sporadic biological diagnosis. Burden of pertussis is not well understood and local data are needed. METHODS: Hospital-based prospective study implementing molecular laboratory testing in infants aged ≤6 months and presenting ≥5 days of cough associated to one pertussis-like symptom in Tehran. Household and non-household contact cases of positive infants were evaluated by comprehensive pertussis diagnosis (molecular testing and serology) regardless of clinical signs. Clinical evaluation and source of infection were described. RESULTS: A total of 247 infants and 130 contact cases were enrolled. Pertussis diagnosis result was obtained for 199 infants and 104 contact cases. Infant population was mostly < 3 months old (79.9%; 157/199) and unvaccinated (62.3%; 124/199), 20.1% (40/199) of them were confirmed having B. pertussis infection. Greater cough duration and lymphocyte counts were the only symptoms associated to positivity. Half of the contact cases (51.0%; 53/104) had a B. pertussis infection, median age was 31 years old. A proportion of 28.3% (15/53) positive contacts did not report any symptom. However, 67.9% (36/53) and 3.8% (2/53) of them reported cough at inclusion or during the study, including 20.8% (11/53) who started coughing ≥7 days before infant cough onset. Overall, only five samples were successfully cultured. CONCLUSION: These data evidenced the significant prevalence of pertussis infection among paucy or poorly symptomatic contacts of infants with pertussis infection. Widespread usage of molecular testing should be implemented to identify B. pertussis infections.

Pediatric Infectious Disease Group (GPIP) position paper on the immune debt of the COVID-19 pandemic in childhood, how can we fill the immunity gap?

Since the beginning of the COVID-19 pandemic, reduced incidence of many viral and bacterial infections has been reported in children: bronchiolitis, varicella, measles, pertussis, pneumococcal and meningococcal invasive diseases. The purpose of this opinion paper is to discuss various situations that could lead to larger epidemics when the non-pharmaceutical interventions (NPI) imposed by the SARS-CoV-2 epidemic will no longer be necessary. While NPIs limited the transmission of SARS-CoV-2, they also reduced the spread of other pathogens during and after lockdown periods, despite the re-opening of schools since June 2020 in France. This positive collateral effect in the short term is welcome as it prevents additional overload of the healthcare system. The lack of immune stimulation due to the reduced circulation of microbial agents and to the related reduced vaccine uptake induced an "immunity debt" which could have negative consequences when the pandemic is under control and NPIs are lifted. The longer these periods of "viral or bacterial low-exposure" are, the greater the likelihood of future epidemics. This is due to a growing proportion of "susceptible" people and a declined herd immunity in the population. The observed delay in vaccination program without effective catch-up and the decrease in viral and bacterial exposures lead to a rebound risk of vaccine-preventable diseases. With a vaccination schedule that does not include vaccines against rotavirus, varicella, and serogroup B and ACYW Neisseria meningitidis, France could become more vulnerable to some of these rebound effects.

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.

Vaccination coverage rates for Diphtheria, Tetanus, Poliomyelitis and Pertussis booster vaccination in France between 2013 and 2017: Learnings from an analysis of National Health System Real-World Data.

BACKGROUND: Maintaining a high vaccination coverage rate (VCR) throughout the lifetime and complying with the National Immunization Program are essential to optimize the protection of the population. The study objectives were to evaluate the evolution of the VCRs and the compliance with the vaccination visits for the diphtheria, tetanus, poliomyelitis and pertussis boosters in France since the changes implemented in the 2013 National Immunization Program. METHODS: Cumulative booster VCRs were estimated at all vaccination visits, from 2013 to 2017, among persons eligible for a booster vaccination from a 1/97th random sample of French claims data. Broader age groups around the recommended ages by the vaccination schedule (6, 11-13, 25, 45, 65, 75, 85, 95y) were used: all persons aged 5 to 8, 10 to 15, 21 to 29, 41 to 49, 61 to 69, 71 to 79, 81 to 89 and 91 to 99. RESULTS: Over the study period, the diphtheria-tetanus-poliomyelitis booster VCRs increased, reaching in 2017: 73.3% at 8 years old, 75.6% at 15 years old, 46.6% at 29 years old, 38.4% at 49 years old, 36.3% at 69 years old, 30.8% at 79 years old, 22.1% at 89 years old and 11.0% at 99 years old. The pertussis VCRs were also increasing at all vaccination visits, in particular at the vaccination visits at 6 and 11-13 years old (from 16.4% to 63.8% and from 50.3% to 61.2%, respectively). Delayed vaccinations were observed at all vaccination visits. CONCLUSION: VCRs for Diphtheria, Tetanus, Poliomyelitis and Pertussis booster vaccination increased from 2013 to 2017 while remaining suboptimal across all ages and lower in the adult populations. The analysis also shows that the introduction in 2013 of a pertussis vaccination at 6 years of age was relatively well-established in 2017 while other changes in recommendations were slowly or partially implemented.

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 1st booster doses in a timely manner. Timeliness of the 2nd booster was lower (63.3%). Rate of seropositive samples continuously and significantly increased from 1-2 to 5-6 years after 1st 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 2nd 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 2nd 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.

Pertussis in infants, in their mothers and other contacts in Casablanca, Morocco.

BACKGROUND: In recent decades, there has been a marked increase in the number of reported cases of pertussis around the world, and pertussis continues to be a frequently occurring disease despite an effective childhood vaccination. This study aims to determine the role of household contacts of children diagnosed with pertussis in Casablanca Morocco. METHODS: From November 2015 to October 2017, children suspected of whooping cough that consulted Ibn Rochd University hospital at Casablanca with their household contacts were enrolled in the study. Nasopharyngeal (NP) samples of the suspected children were analyzed by culture and RT-PCR. For the household contacts, NP and blood samples were collected and analyzed by RT-PCR and specific detection of pertussis toxin antibodies by ELISA, respectively. RESULTS: During the study period, the survey was carried out on 128 infants hospitalized for pertussis suspicion and their families (N = 140). B. pertussis DNA was specifically detected in 73 (57%) samples, coexistence of B. pertussis and B. parapertussis DNA in 3 (2.3%) samples, coexistence of B. pertussis and B. holmesii DNA in 10 (7.81%) and only one (0.78%) sample was IS 481 RT-PCR positive without the possibility of determining the Bordetella species with the diagnostic tools used. Confirmations of Pertussis infection in household contacts by culture, RT- PCR and serology were 10, 46 and 39%, respectively. B. pertussis DNA was confirmed in the infants as well in their mothers in 38% of the cases. Co detection of B. pertussis and B. parapertussis DNA in 2% and co-detection of B. pertussis and B. holmesii DNA in 4%. B. holmesii DNA alone was detected in 5 NP samples of index cases and their mothers. CONCLUSIONS: The results of this study confirm that B. pertussis is still circulating in children and adults, and were likely a source of pertussis contamination in infants still not vaccinated. The use of RT-PCR specific for B. pertussis in the diagnosis of adults is less sensitive and should be associated with serologic tests to improve diagnosis of pertussis and contributes to preventing transmission of the disease in infants.

Pertussis vaccines: The first hundred years.

Vaccines against pertussis have been used for more than a hundred years. This review describes the development of whole-cell (wP) and acellular pertussis (aP) vaccines, which, as DTP combination vaccines, have significantly reduced morbidity and mortality from pertussis, and which currently serve as the building blocks for a variety of vaccines used to immunize all infants worldwide. Two series of efficacy trials done in the 1950s for wP vaccines and in the 1990s for aP-vaccines have established standards for studying vaccine effectiveness. However, irrespective of their longtime use, critical aspects of pertussis vaccines remain unknown, including the exact mechanisms of protective immunity and a correlate of protection. Research to improve on the effectiveness and the duration of protection is ongoing, but although the vaccines are not perfect, only their continued use with a high coverage will ensure that infants and children are being protected from pertussis.

Pertussis in Low and Medium Income Countries: A Pragmatic Approach.

Pertussis is a vaccine preventable disease since late 1940s. However, it is still endemic in all countries and occurs in epidemic cycles. The number of cases/deaths has decreased during the last decade but a high number of deaths persists in Low and Medium Income Countries (LMIC). The epidemiological situation in LMIC is not precisely known due to lack of surveillance and specific diagnostic tools. A pragmatic approach in these countries should be to establish; (i) a hospital-based surveillance in the largest cities of the country with clinicians and nurses trained to detect clinical symptoms, to obtain biological samples for specific analysis and diagnosis; (ii) a reference laboratory as part of an international network of reference laboratories, under quality assurance, and able to perform at least PCR diagnosis and if possible detection of antibiotic resistance. This surveillance network would allow specific diagnosis of pertussis and facilitate the reporting of cases at national level, thereby improving awareness of the disease at clinician, population and decision maker levels. This network could allow a better evaluation of vaccine coverage, timely vaccination and impacts of modification of national vaccine strategy or type of pertussis vaccine used. Collaboration between this network and basic scientists should be strengthened through translational research projects in order to improve fundamental knowledge on pertussis in LMIC and help clinicians' access to specific diagnostic tools.

Pertactin-Negative and Filamentous Hemagglutinin-Negative Bordetella pertussis, Australia, 2013-2017.

During the 2008-2012 pertussis epidemic in Australia, pertactin (Prn)-negative Bordetella pertussis emerged. We analyzed 78 isolates from the 2013-2017 epidemic and documented continued expansion of Prn-negative ptxP3 B. pertussis strains. We also detected a filamentous hemagglutinin-negative and Prn-negative B. pertussis isolate.

Seroprevalence of pertussis among healthcare workers: A cross-sectional study from Tunisia.

This cross-sectional study aimed to assess pertussis seroprevalence among healthy healthcare workers (HCW) of the Children's Hospital of Tunis, Tunisia. During the study period, 236 blood samples were obtained to determine HCW exposure to pertussis. Concentrations of immunoglobulin G (IgG) to pertussis toxin (PT) were measured using a commercial enzyme-linked immunosorbent assay. Cut-offs values used were 40 and 100 IU/ml, respectively indicative of an infection within the last year and a current/recent infection. Overall, seropositivity rate was 11.4% (95% CI 7.4-15.5) and 2.5% (95% CI 0.5-4.6) of ELISA results were indicative of a current infection. Seroprevalence was significantly most important in nurses (p = 0.03) and in participants aged 21-31y (p = 0.009). Our study confirmed that pertussis is circulating in hospital settings and affecting Tunisian HCW, in close contact with infants. Therefore, a booster dose of acellular pertussis vaccine needs to be considered.

Pertussis epidemiology in Tunisian infants and children and characterization of Bordetella pertussis isolates: results of a 9-year surveillance study, 2007 to 2016.

PURPOSE: Pertussis remains a public health concern in most countries. Our study aimed to prospectively explore the epidemiology of pertussis in the Tunis area of Tunisia between 2007 and 2016, and to characterize the virulence-associated genes of the collected Bordetella pertussis isolates. METHODOLOGY: Infants and children hospitalized at the Children's Hospital of Tunis, Tunisia, between 2007 and 2016 for suspicion of pertussis were enrolled in the study. Culture and real-time PCR (qPCR) assays targeting IS481, IS1001, recA, H-IS1001 and ptxP were used to confirm the pertussis diagnosis. Phenotypic and genotypic characterization of recovered isolates was performed.Results/Key findings. A total of 1844 children were included in the study. Overall, 306 children (16.6 %) with Bordetella infection were confirmed by qPCR. Among them, 265 (86.6 %) were confirmed as having B. pertussis (IS481+, ptxP+, H-IS1001-), 18 (5.9 %) as having Bordetella parapertussis (IS481-, IS1001+) and 11 (3.6 %) as having Bordetella spp. (IS481+, ptxP-, H-IS1001-). No Bordetella holmesii (IS481+, IS1001-, H-IS1001+) was identified. The estimated pertussis incidence in the Tunis area was 134/100 000 in children aged less than 5 years. Two epidemic peaks were observed in 2009 and 2014. Ten B. pertussis isolates were cultured and characterized. Deficiency in pertactin expression was not observed, and genotyping of the isolates revealed a predominant allelic profile: ptxP3-ptxA1-prn2-fim2-1-fim3-2. CONCLUSION: This study demonstrated that pertussis is still present as a cyclical disease in Tunisia, despite high primo-vaccination coverage with a pertussis whole-cell vaccine. The predominant genotype of Tunisian B. pertussis isolates is similar to isolates circulating in countries using the acellular vaccine.

A cross-sectional study of Bordetella pertussis seroprevalence and estimated duration of vaccine protection against pertussis in St. Petersburg, Russia.

BACKGROUND: In Russia as in other countries introduction of infant vaccination against pertussis in 1950s led to dramatic decrease of whooping cough. The current vaccination schedule includes a 3-dose infant series and toddler booster; the pre-school booster was cancelled in 1980s and never reintroduced. Whole-cell vaccines, and in a smaller proportion acellular vaccines are used for all doses. However, pertussis incidence in urban settings is high with highest burden in school children. We conducted a study of seroprevalence of recent pertussis infection to estimate the duration of protection from the 4-dose series. MATERIALS AND METHODS: Sera sample from 395 St Petersburg children aged ≥3 years and <14 years were tested for pertussis toxin antibodies using a commercial PT ELISA test. Only children with completed 4-dose vaccination course were included in the study. Age-specific seroprevalence of recent pertussis infection was analyzed for trends. RESULTS: Children fully vaccinated against pertussis at 3 years old had significant delays in infant vaccination schedule: only 83.5% received at least one dose of pertussis vaccine at 6 months of age and 25.6% received their toddler booster before 24 months-old. Overall, 10.6% of children demonstrated the serological signs of the infection in the last 12 months. A clear trend (r2 = 0.692) of increasing proportion of infection in the last 12 months was observed in children who had received their last dose of vaccine 6 years and more prior to the study. CONCLUSION: Our study demonstrates that Russian children become susceptible to infection at or soon after entering school. The results confirm the waning of vaccine-elicited immunity around school-age and support the need for a booster dose at that age.

Whooping cough surveillance in France in pediatric private practice in 2006-2015.

BACKGROUND: Increasing incidence of whooping cough (pertussis) has been reported in many countries, attributed to a switch from whole-cell pertussis-containing vaccine (wPV) to acellular PV (aPV) and circulation of the pertactin non-producing Bordetella pertussis. The present study aimed to estimate the duration of immunity conferred by PVs in children in France with data from an ongoing pediatric ambulatory surveillance of pertussis. METHODS: A total of 64 pediatricians throughout France enrolled children with suspected pertussis. A standardized data form was used to collect data on age sex, vaccination status, brand of wPV or aPV and source of infection. Confirmed cases were positive on culture and/or real-time Polymerase Chain Reaction (for B.-non-classified or B. pertussis or B. parapertussis) and/or pertussis serology. RESULTS: Between October 2006 and December 2015, 149 cases of confirmed Bordetella infections were reported, 86 infected with B. pertussis and 55 B. non-classified. Fifteen children (10.1%) were not vaccinated, and 26 (17.4%) were partially vaccinated. The mean age was greater for children who received 4 doses of wPV (11.3±2.2, p<0.001) or a combination of wPV and aPV (10.5±3.3, p<0.001) than only aPV (7.2±2.4years). The mean duration of cough before a visit to a pediatrician was longer for children with wPV or a combination of wPV and aPV than only aPV (23.8±10.1 and 25.0±25.6vs 13.6±10.0days). CONCLUSION: Despite the use of a more sensitive diagnostic method and emergence of pertactin non producing B. pertussis, in France context, aPV-induced immunity still protects against pertussis; however, the mean duration of immunity is about 6 to 7years, compared to 9years for wPV vaccine, after the primary vaccination and one booster (3+1 doses).

Bordetella Adenylate Cyclase-Hemolysin Toxins.

Adenylate cyclase-hemolysin toxin is secreted and produced by three classical species of the genus Bordetella: Bordetella pertussis, B. parapertussis and B. bronchiseptica. This toxin has several properties such as: (i) adenylate cyclase activity, enhanced after interaction with the eukaryotic protein, calmodulin; (ii) a pore-forming activity; (iii) an invasive activity. It plays an important role in the pathogenesis of these Bordetella species responsible for whooping cough in humans or persistent respiratory infections in mammals, by modulating host immune responses. In contrast with other Bordetella toxins or adhesins, lack of (or very low polymorphism) is observed in the structural gene encoding this toxin, supporting its importance as well as a potential role as a vaccine antigen against whooping cough. In this article, an overview of the investigations undertaken on this toxin is presented.