Strategies to control pertussis in infants

Evaluation of pre-school pertussis booster vaccination in Shanghai, China: A cost-effectiveness analysis

BACKGROUND

In recent years, notified pertussis cases have been increasingly documented in China. It raised a new public health concern of potential optimization in immunization strategy. This study was aimed to determine the cost-effectiveness of different immunization strategies against pertussis-containing vaccines for 6-year-old pre-school children in Shanghai.

METHODS

A Markov-decision tree model was applied to evaluate two pertussis immunization strategies for 6-year-old pre-school children as following: (1) 1 dose of acellular pertussis (aP) contained vaccine (DTaP or Tdap) booster vaccinated at 6 years of age, and (2) no booster at 6 years of age regimen. Primary outcomes included quality-adjusted life years (QALYs), costs, and incremental cost-utility ratios (ICUR). Sensitivity analyses were performed. The analysis was conducted over a study period of 14 years from a societal perspective.

RESULTS

Compared to no booster immunization strategy, administering 1 dose of acellular pertussis (aP) contained vaccine (DTaP or Tdap) booster at 6 years of age, resulted in an average cost reduction of CNY 814.16 (USD 116) per individual, an increase in QALYs by 0.00066, and a rise in per capita net monetary benefit (NMB) by CNY 933.51 (USD 132). The total costs over the study period were reduced by CNY 160.59 million (USD 23 million), utility increased by 130.49 QALYs, and NMB increased by CNY 184.14 million (USD 26 million).

CONCLUSIONS

Implementing acellular pertussis booster immunization for 6-year-old pre-school children in Shanghai emerges as a cost-saving immunization strategy, with both cost savings and utility gains.

Long-term variations of urban-Rural disparities in infectious disease burden of over 8.44 million children, adolescents, and youth in China from 2013 to 2021: An observational study

BACKGROUND

An accelerated epidemiological transition, spurred by economic development and urbanization, has led to a rapid transformation of the disease spectrum. However, this transition has resulted in a divergent change in the burden of infectious diseases between urban and rural areas. The objective of our study was to evaluate the long-term urban-rural disparities in infectious diseases among children, adolescents, and youths in China, while also examining the specific diseases driving these disparities.

METHODS AND FINDINGS

This observational study examined data on 43 notifiable infectious diseases from 8,442,956 cases from individuals aged 4 to 24 years, with 4,487,043 cases in urban areas and 3,955,913 in rural areas. The data from 2013 to 2021 were obtained from China's Notifiable Infectious Disease Surveillance System. The 43 infectious diseases were categorized into 7 categories: vaccine-preventable, bacterial, gastrointestinal and enterovirus, sexually transmitted and bloodborne, vectorborne, zoonotic, and quarantinable diseases. The calculation of infectious disease incidence was stratified by urban and rural areas. We used the index of incidence rate ratio (IRR), calculated by dividing the urban incidence rate by the rural incidence rate for each disease category, to assess the urban-rural disparity. During the nine-year study period, most notifiable infectious diseases in both urban and rural areas exhibited either a decreased or stable pattern. However, a significant and progressively widening urban-rural disparity in notifiable infectious diseases was observed. Children, adolescents, and youths in urban areas experienced a higher average yearly incidence compared to their rural counterparts, with rates of 439 per 100,000 compared to 211 per 100,000, respectively (IRR: 2.078, 95% CI [2.075, 2.081]; p < 0.001). From 2013 to 2021, this disparity was primarily driven by higher incidences of pertussis (IRR: 1.782, 95% CI [1.705, 1.862]; p < 0.001) and seasonal influenza (IRR: 3.213, 95% CI [3.205, 3.220]; p < 0.001) among vaccine-preventable diseases, tuberculosis (IRR: 1.011, 95% CI [1.006, 1.015]; p < 0.001), and scarlet fever (IRR: 2.942, 95% CI [2.918, 2.966]; p < 0.001) among bacterial diseases, infectious diarrhea (IRR: 1.932, 95% CI [1.924, 1.939]; p < 0.001), and hand, foot, and mouth disease (IRR: 2.501, 95% CI [2.491, 2.510]; p < 0.001) among gastrointestinal and enterovirus diseases, dengue (IRR: 11.952, 95% CI [11.313, 12.628]; p < 0.001) among vectorborne diseases, and 4 sexually transmitted and bloodborne diseases (syphilis: IRR 1.743, 95% CI [1.731, 1.755], p < 0.001; gonorrhea: IRR 2.658, 95% CI [2.635, 2.682], p < 0.001; HIV/AIDS: IRR 2.269, 95% CI [2.239, 2.299], p < 0.001; hepatitis C: IRR 1.540, 95% CI [1.506, 1.575], p < 0.001), but was partially offset by lower incidences of most zoonotic and quarantinable diseases in urban areas (for example, brucellosis among zoonotic: IRR 0.516, 95% CI [0.498, 0.534], p < 0.001; hemorrhagic fever among quarantinable: IRR 0.930, 95% CI [0.881, 0.981], p = 0.008). Additionally, the overall urban-rural disparity was particularly pronounced in the middle (IRR: 1.704, 95% CI [1.699, 1.708]; p < 0.001) and northeastern regions (IRR: 1.713, 95% CI [1.700, 1.726]; p < 0.001) of China. A primary limitation of our study is that the incidence was calculated based on annual average population data without accounting for population mobility.

CONCLUSIONS

A significant urban-rural disparity in notifiable infectious diseases among children, adolescents, and youths was evident from our study. The burden in urban areas exceeded that in rural areas by more than 2-fold, and this gap appears to be widening, particularly influenced by tuberculosis, scarlet fever, infectious diarrhea, and typhus. These findings underscore the urgent need for interventions to mitigate infectious diseases and address the growing urban-rural disparity.

Maternal Pertussis Vaccination, Infant Immunization, and Risk of Pertussis

OBJECTIVES

Following the introduction of jurisdictional maternal pertussis vaccination programs in Australia, we estimated maternal vaccine effectiveness (VE) and whether maternal pertussis vaccination modified the effectiveness of the first 3 primary doses of pertussis-containing vaccines.

METHODS

We conducted a population-based cohort study of 279 418 mother-infant pairs using probabilistic linkage of administrative health records in 3 Australian jurisdictions. Infants were maternally vaccinated if their mother had a documented pertussis vaccination ≥14 days before birth. Jurisdictional immunization records were used to identify receipt of the first 3 infant doses of pertussis-containing vaccines. Infant pertussis infections were identified using notifiable disease records. VE was estimated using Cox proportional hazard models.

RESULTS

Pertussis was administered during 51.7% (n = 144 429/279 418) of pregnancies, predominantly at 28-31 weeks' gestation. VE of maternal pertussis vaccination declined from 70.4% (95% confidence interval [CI], 50.5-82.3) among infants <2 months old to 43.3% (95% CI, 6.8-65.6) among infants 7-8 months old and was not significant after 8 months of age. Although we observed slightly lower VE point estimates for the third dose of infant pertussis vaccine among maternally vaccinated compared with unvaccinated infants (76.5% vs 92.9%, P = .002), we did not observe higher rates of pertussis infection (hazard ratio, 0.70; 95% CI, 0.61-3.39).

CONCLUSIONS

Pertussis vaccination near 28 weeks' gestation was associated with lower risk of infection among infants through 8 months of age. Although there was some evidence of lower effectiveness of infant vaccination among maternally vaccinated infants, this did not appear to translate to greater risk of disease.

Novel murine model reveals an early role for pertussis toxin in disrupting neonatal immunity to Bordetella pertussis

The increased susceptibility of neonates to specific pathogens has previously been attributed to an underdeveloped immune system. More recent data suggest neonates have effective protection against most pathogens but are particularly susceptible to those that target immune functions specific to neonates. Bordetella pertussis (Bp), the causative agent of "whooping cough", causes more serious disease in infants attributed to its production of pertussis toxin (PTx), although the neonate-specific immune functions it targets remain unknown. Problematically, the rapid development of adult immunity in mice has confounded our ability to study interactions of the neonatal immune system and its components, such as virtual memory T cells which are prominent prior to the maturation of the thymus. Here, we examine the rapid change in susceptibility of young mice and define a period from five- to eight-days-old during which mice are much more susceptible to Bp than mice even a couple days older. These more narrowly defined "neonatal" mice display significantly increased susceptibility to wild type Bp but very rapidly and effectively respond to and control Bp lacking PTx, more rapidly even than adult mice. Thus, PTx efficiently blocks some very effective form(s) of neonatal protective immunity, potentially providing a tool to better understand the neonatal immune system. The rapid clearance of the PTx mutant correlates with the early accumulation of neutrophils and T cells and suggests a role for PTx in disrupting their accumulation. These results demonstrate a striking age-dependent response to Bp, define an early age of extreme susceptibility to Bp, and demonstrate that the neonatal response can be more efficient than the adult response in eliminating bacteria from the lungs, but these neonatal functions are substantially blocked by PTx. This refined definition of "neonatal" mice may be useful in the study of other pathogens that primarily infect neonates, and PTx may prove a particularly valuable tool for probing the poorly understood neonatal immune system.

Safety of COVID-19 vaccination in women undergoing IVF/ICSI treatment - Clinical study and systematic review

Background

It was suggested that vaccination in general might affect reproductive health. Safety of COVID-19 vaccination in women undergoing assisted reproductive techniques (ART) treatment is not well established.

Methods

We performed a retrospective study including 536 women undergoing fresh embryo transfer after IVF/ICSI treatment in a huge IVF center in southern China to investigate the effect of COVID-19 vaccination on oocyte maturation, fertilization rate, blastulation rate, implantation rate, clinical pregnancy rate and miscarriage rate. In addition, we performed a systematic review of existing studies on the safety of COVID-19 vaccination in women undergoing ART treatment.

Results

In our study, 268 women received inactivated or recombinant COVID-19 vaccination and 268 controls were enrolled based on propensity score matching. We observed a decreased fertilization rate and signs for impaired oocyte maturation in vaccinated women. Besides our study, there were 15 studies analyzing the safety of COVID-19 vaccination in women undergoing ART treatment. For the mRNA vaccines, no adverse signals were reported concerning oocyte maturation, fertilization rate, blastulation rate, implantation rate, clinical pregnancy rate and miscarriage rate. In women being vaccinated with an inactivated vaccine, implantation rate, clinical pregnancy rate and miscarriage rate were not affected, whereas oocyte maturation and fertilization rate were impaired.

Conclusions

Vaccination against COVID-19 in women undergoing ART treatment seems to be safe especially for women getting mRNA vaccines. The effects on oocyte maturation and fertilization rate of inactivated and recombinant COVID-19 vaccinations might be a safety signal and need further investigation and independent confirmation.

Intention and Attitude to Accept a Pertussis Cocooning Vaccination among Chinese Children's Guardians: A Cross-Sectional Survey

OBJECTIVE

to assess Chinese children's guardians' intentions and attitudes toward accepting a pertussis cocooning vaccination and its determinants.

METHODS

a self-administered questionnaire was designed based on a theoretical framework that originated mainly from the reasoned action approach. Associations between questionnaire variables and outcomes were assessed using univariate and multivariate analyses with odds ratios (OR), regression coefficients (β), and their 95% confidence intervals (CIs).

RESULTS

among 762 eligible participants, most (80.71%) reported a positive intention to accept a pertussis cocooning vaccination. The guardians' positive intention was related to the children's pertussis vaccination experience (OR = 2.483, 95% CI: 1.340-4.600). Guardians who had a positive attitude towards pertussis vaccination (OR = 1.554, 95% CI: 1.053-2.296), higher subjective norms (OR = 1.960, 95% CI: 1.371-2.802) and better perceived behavioral control (OR = 7.482, 95% CI: 4.829-11.591) stated a higher intention to receive a pertussis cocooning vaccination. The mean attitude score was 3.88 ± 0.863. Greater risk perception about pertussis (β = 0.390, 95% CI: 0.298-0.483), stronger obligation from moral norms (β = 0.355, 95% CI: 0.279-0.430), and good knowledge (β = 0.108, 95% CI: 0.070-0.146) were significantly related to positive attitude toward pertussis cocooning vaccination among guardians.

CONCLUSIONS

Chinese children's guardians held positive intentions and attitudes toward accepting a pertussis cocooning vaccination. The current findings described the determinants of such intention and attitude and provided knowledge based on improving guardians' intentions for policymakers if cocooning vaccinations or related immunization strategies are implemented in China in the future.

Seroepidemiology of pertussis in the east of China: Estimates of incidence of infection in adolescents and adults pre- and post-COVID-19

Introduction

The dramatic decrease in the number of reported cases of pertussis during COVID-19 pandemic has been underestimated. The objective was to compare the estimated incidence rate of pertussis in populations pre- and post-COVID-19 pandemic by analyzing the anti-pertussis toxin (anti-PT) IgG and anti-filamentous hemagglutininant (anti-FHA) IgG antibodies in healthy Chinese population from 2018 to 2021.

Methods

All serum samples (N = 1,000) were collected from healthy population (aged ≥ 15 years) who attended an annual monitoring project of antibody levels in Jiangsu province in 2018-2021 were measured by ELISA.

Results

The positive rates of anti-PT IgG and anti-FHA IgG antibodies were 11.4% (114/1,000) and 20.2% (202/1,000) (≥40 IU/ml), the GMC were 17.25 (95% CI: 15.49-19.03) IU/mL and 24.94 (95% CI: 22.73-27.16) IU/mL in the study population, respectively. The percentage of participants with anti-PT IgG antibodies higher than 40 IU/mL was 5.20% (11/212) in 2018, 5.5% (19/348) in 2019, 21.2% (46/217) in 2020 and 17.0% (38/223) in 2021, respectively. The non-detectable rate (<5 IU/mL) of anti-PT IgG antibodies was 16.9, 17.7, 28.1, and 37.3% in 2018, 2019, 2020, and 2021, respectively. We assumed that the infection occurred within 58.6 days, and based on the overall proportion (2.9%) of individuals with anti-PT IgG antibody ≥100 IU/ml, the incidence rate (/100) was estimated by the formula to be 18.08 (95% CI: 12.40-26.11). In addition, the estimated incidence of Post-COVID-19 was higher than that of Pre-COVID-19 (36.33/100 vs. 12.84/100), and the difference was statistically significant (p < 0.05).

Conclusions

Our results suggest a high rate of under-reporting of pertussis in Jiangsu Province both pre- and post-COVID-19 pandemic, and there are a large number of adults of childbearing age who are susceptible to pertussis. It seems imperative that vaccination of adolescents and adults should be considered for inclusion in vaccination programs.

Influences on Pregnant Women's and Health Care Professionals' Behaviour Regarding Maternal Vaccinations: A Qualitative Interview Study

The uptake of maternal influenza and pertussis vaccinations is often suboptimal. This study explores the factors influencing pregnant women's and health care professionals' (HCPs) behaviour regarding maternal vaccinations (MVs). Pregnant/recently pregnant women, midwives, pharmacists and general practice staff in Waikato, New Zealand, were interviewed. The analysis used the behaviour change wheel model. Interviews of 18 women and 35 HCPs revealed knowledge about MVs varied with knowledge deficiencies hindering the uptake, particularly for influenza vaccination. HCPs, especially midwives, were key in raising women's awareness of MVs. Experience with vaccinating, hospital work (for midwives) and training increased HCPs' knowledge and proactivity about MVs. A "woman's choice" philosophy saw midwives typically encouraging women to seek information and make their own decision. Women's decisions were generally based on knowledge, beliefs, HCPs' emphasis and their perceived risk, with little apparent influence from friends, family, or online or promotional material. General practice's concentration on children's vaccination and minimal antenatal contact limited proactivity with MVs. Busyness and prioritisation appeared to affect HCPs' proactivity. Multi-pronged interventions targeting HCPs and pregnant women and increasing MV access are needed. All HCPs seeing pregnant women should be well-informed about MVs, including how to identify and address women's questions or concerns about MVs to optimise uptake.

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.

Improving vaccination of pregnant women against seasonal influenza through use of a mandatory field in the obstetric electronic medical record

BACKGROUND

The aim of the present study was to determine whether using a mandatory data field in an electronic health record would increase compliance with the recommendation to vaccinate pregnant women against influenza.

METHODS

Two cohorts of women who delivered at the Centenary Hospital for Women and Children between 1-31 July 2015 and 1-31 July 2017 were compared for compliance with the national public health recommendation to vaccinate all pregnant women against influenza. The single change between audit periods was programming the electronic health record to include a mandatory field preventing clinicians from closing patient files unless they selected an answer to the question asking whether influenza vaccination had been performed. Data were audited and compliance rates were compared.

RESULTS

A total of 275 and 299 women delivered in the two audit periods. There were no significant differences in maternal or neonatal characteristics between the two cohorts except for maternal age, which was younger in the second period (33.3 versus 31.5 years; P = 0.001). Vaccination rates doubled between audit periods (35.0% versus 79.8%, P < 0.0001).

CONCLUSION

Introducing a mandatory data field into an electronic health record system may increase compliance with public health interventions, such as influenza vaccination in pregnant women.

Pertussis immunisation during pregnancy: Antibody levels and the impact of booster vaccine

Pertussis (whooping cough) is a highly infectious disease caused by Bordetella pertussis. Mothers lacking adequate immunity and contracting the disease represent the biggest risk of transmission to new-borns, for which the disease is often a threat. The aim of the study was to estimate the frequency of pertussis susceptibility among pregnant women, in order to point out the need for a vaccine recall during pregnancy, and to evaluate the antibody response in already vaccinated women. A cross-sectional observational study was conducted in the blood test centre of "St. Anna" Obstetrics and Gynaecology Hospital in Turin (Piedmont, Italy). Eligibility criteria included pregnant women coming to the centre for any blood test, aged 18 or above and with gestational age between 33 and 37 weeks at the moment of the blood draw. The data collection was carried out from May 2019 to January 2020 and the concentration of anti-Pertussis Toxin (anti-PT) IgG was measured through the Enzyme-Linked Immunosorbent Assay (ELISA) technique. Two-hundred women (median age 35) were enrolled: 132 (66%) had received at least one dose of pertussis vaccine, 82 of which during pregnancy. Recently vaccinated women had significantly higher antibody titres (even 12-15 times as high) compared to those vaccinated more than 5 years before or never vaccinated at all (p < 0.0001). Moreover, 95.1% of recently vaccinated women had anti-PT IgG levels above 10 IU/ml, and 85.4% above 20 IU/ml, while the same proportions were as low as 37% and 21% (respectively) in the group of women not vaccinated in pregnancy. This study confirmed that the vaccination is greatly effective in ensuring high antibody titres in the first months after the booster vaccine, with considerable differences in anti-PT IgG compared to women vaccinated earlier or never vaccinated at all, and therefore vaccinating pregnant women against pertussis still represents a valuable strategy.

Intention to accept pertussis vaccination among Chinese people older than age 5

Background: The intention of Chinese people older than age 5 to accept the pertussis vaccination is unknown, which is important for the future design of an effective pertussis vaccination program in China.Method: We conducted a cross-sectional survey among people older than age 5 in China. A 24-item questionnaire was used to explore the determinants of intention to accept a pertussis vaccination, and for children and adolescents (≦15 years old), their guardian was required to help answer the questionnaire on their behalf. Univariate and multivariate logistic regression was used to analyze the influencing factors of intention.Results: A total of 3,041 individuals participated in our survey and 3025 completed the questionnaire, among which 1938 (64.07%) reported a positive intention to be vaccinated. A multiple logistic regression analysis revealed that the main positive factors for the intention to accept pertussis vaccination were younger age (Odd ratio [OR] 0.838, P < .001), higher educational attainment (OR 1.171, P = .002), no hospitalization because of the most recent cough (OR 2.468, P < .001), awareness about pertussis (OR 1.958, P < .001), and consideration of pertussis vaccination to be safe (OR 1.450, P = .026).Conclusion: There is a relatively high level of intention to receive the pertussis vaccine among people older than age 5 in China. Future pertussis vaccination strategies geared at them should consider focusing on middle-aged and older individuals and those with a low education as well as strengthen the promotion of disease characteristics, vaccine effectiveness, and safety.

Uptake of vaccination in pregnancy

Maternal immunisation is a public health strategy that aims to provide protection against certain infections to both mother and her foetus or newborn child. Vaccination of pregnant women induces vaccine-specific antibodies that lead to the subsequent transfer of these antibodies across the placenta or through breastfeeding to the offspring. At present, vaccinations in pregnancy are limited to pertussis, tetanus, diphtheria, polio, and the seasonal Influenza vaccine. Recently, some countries have incorporated routine antenatal vaccinations in their national immunisation programmes. Future vaccines targeted at pregnant women such as respiratory syncytial virus (RSV) and Group B streptococcus (GBS) are under development. The recently approved Covid-19 vaccines have no safety data for use in pregnancy at present, but have been considered in the UK in extremely vulnerable pregnant women or pregnant frontline health and social care workers.

In this article, we review the evidence supporting maternal immunisation and discuss the uptake of vaccines in pregnant women, challenges of recording the data on vaccine coverage, and consider reasons behind the present levels of uptake and strategies for future improvements.

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.

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.

Rapid and simple SNP genotyping for Bordetella pertussis epidemic strain MT27 based on a multiplexed single-base extension assay

Multilocus variable-number tandem repeat analysis (MLVA) is widely used for genotyping of Bordetella pertussis, the causative bacteria for pertussis. However, MLVA genotyping is losing its discriminate power because prevalence of the epidemic MT27 strain (MLVA-27) is increasing worldwide. To address this, we developed a single nucleotide polymorphism (SNP) genotyping method for MT27 based on multiplexed single-base extension (SBE) assay. A total of 237 MT27 isolates collected in Japan during 1999–2018 were genotyped and classified into ten SNP genotypes (SG1 to SG10) with a Simpson’s diversity index (DI) of 0.79 (95% CI 0.76–0.82). Temporal trends showed a marked increase in the genotypic diversity in the 2010s: Simpson’s DI was zero in 1999–2004, 0.16 in 2005–2009, 0.83 in 2010–2014, and 0.76 in 2015–2018. This indicates that the SNP genotyping is applicable to the recently circulating MT27 strain. Additionally, almost all outbreak-associated MT27 isolates were classified into the same SNP genotypes for each outbreak. Multiplexed SBE assay allows for rapid and simple genotyping, indicating that the SNP genotyping can potentially be a useful tool for subtyping the B. pertussis MT27 strain in routine surveillance and outbreak investigations.

Safety of maternal pertussis vaccination on pregnancy and birth outcomes: A prospective cohort study

OBJECTIVE

To evaluate the safety of maternal pertussis vaccination on pregnancy and birth outcomes.

METHODS

The study population comprised 1272 healthy nulliparous pregnant women who participated in Screening Tests to identify poor Outcomes in Pregnancy (STOP) study at two obstetric hospitals in South Australia between 2015 and 2018. Participants were followed prospectively, with vaccination (confirmed by medical records), extensive amounts of pregnancy and birth outcome data collected by research midwives. Adjusted relative risks (aRRs) and hazard ratios (aHRs) were estimated accounting for time-varying vaccine exposure and the temporal nature of each outcome.

RESULTS

Of the 1272 women included in this study, 80.1% (n = 1019) received maternal pertussis vaccination. Vaccinated women had an average 0.22 weeks (95% CI 0.001, 0.44) longer gestation at delivery compared to unvaccinated women. Maternal pertussis vaccination was not associated with chorioamnionitis (aRR 0.71, 95% CI 0.27,1.82), gestational hypertension (aHR 1.24, 95% CI, 0.66, 2.30), preeclampsia (aHR 0.75, 95% CI 0.47, 1.18) nor preterm birth (aHR 0.99, 95% CI 0.47, 2.07). Neither risk of low birth weight (aHR 0.72, 95% CI 0.41, 1.27) nor small for gestational age infants (aHR 0.67,95% CI 0.29, 1.55) were increased following maternal pertussis vaccination. No associations between pertussis vaccination during pregnancy and adverse birth outcomes including admission to the neonatal care unit, low Apgar scores, and mechanical ventilation were observed. Results were not materially changed after adjustment for maternal influenza vaccination.

CONCLUSION

Our study provides reassuring evidence of the safety of maternal pertussis vaccination with no increased risk of adverse pregnancy and birth outcomes. These findings support recommendations for pertussis vaccination during pregnancy to prevent morbidity and mortality associated with early-infant pertussis disease.

The historical aspects of vaccination in pregnancy

As we live through the history-making pandemic of coronavirus disease 2019 (COVID-19), it is timely to consider the lessons that history has taught us about vaccine-preventable disease in pregnancy. Vaccinations have earned an established place in pregnancy care to prevent communicable disease in the mother, fetus and newborn. The improvements in maternal and perinatal outcome have been achieved through the evolution and application of new knowledge in many areas. These include recognition of the unique pathogenic consequences of diseases in pregnancy; improved understanding of the maternal immune system and its interplay with the fetus; optimizing safe vaccine development; ensuring pregnant women are included in appropriately designed trials of efficacy, and public health engagement to optimize uptake. As the world eagerly awaits an effective vaccine for COVID 19, these lessons of history help signpost the way, to ensure the potential of vaccinations to reduce morbidity for pregnant women and their newborns is fully realized.

Delivering prenatal pertussis vaccine through maternity services in England: What is the impact on vaccine coverage?

BACKGROUND

Prenatal pertussis vaccination was introduced in 2012 in England and is primarily delivered through general practice. Since 2017 some maternity services are commissioned to offer it too. We aimed to describe the maternity service delivery of prenatal pertussis vaccination and its impact on vaccine uptake.

METHODS

We described the proportion of maternity services in England commissioned to offer pertussis vaccination to pregnant women in 2017/18 and the proportion of women vaccinated in this setting using a self-administered survey of NHS commissioners. We categorised clinical commissioning groups (CCGs) in England into "implementing" and "non-implementing" pertussis vaccination in maternity services. We identified CCGs where vaccination data was reliably transferred from maternity services to primary care records (source of routine data on vaccine uptake) and among those compared changes in vaccine uptake in implementing vs non-implementing CCGs between March 2016 (before implementation) and March 2018 (after).

FINDINGS

Of 141 maternity service units in England, 61% delivered prenatal pertussis vaccine in 2017/18. Of those 57.0% of maternity services immunized less than 10% of pregnant women and only 7.1% of maternity services immunized more than 40% of pregnant women. Between March 2016 and March 2018, coverage increased by 19.6% among non-implementing CCGs compared with 17.8% among all implementing CCGs (difference -2.2, p = 0.48) and 28.2% among implementing CCGs with reliable methods of data transfer (difference 8.6, p = 0.04). This difference translated to a difference of 1.6 percentage points in absolute terms.

INTERPRETATION

Delivering pertussis vaccine through maternity services has a moderate but important impact on vaccine uptake. There is a need to improve data transfer on vaccines administered in maternity service units to primary care. Maternity services should offer the vaccine to improve coverage and thus optimise protection for young infants. Barriers to effective programme implementation should be investigated and addressed.

A Qualitative Study of Views and Experiences of Women and Health Care Professionals about Free Maternal Vaccinations Administered at Community Pharmacies

Background: A policy to extend funding of maternal pregnancy influenza and pertussis vaccinations to community pharmacies could address low pregnancy vaccine uptake. The policy has been implemented in one region in New Zealand. This study explored the views and experiences of women eligible for the vaccines and health care professionals regarding funded maternal vaccinations in pharmacy. Methods: Women in late pregnancy or with an infant, and midwives, pharmacists, and general practice staff were selected purposively and interviewed regarding maternal vaccinations and the new policy, including their awareness and views of the funded vaccinations in pharmacies, and how this policy worked in practice. Enablers and barriers to vaccination by pharmacists were explored. Interviews were transcribed and analysed using a framework approach. Results: Fifty-three interviews were conducted. Most women and health care professionals viewed funded maternal vaccinations in pharmacies positively with respect to increasing awareness and providing delivery options. Many women received messages from pharmacies. Most pharmacies used posters, leaflets and/or verbal explanation to pregnant women to raise awareness of the vaccinations. Not all pharmacies provided these vaccinations, and frontline staff could help to raise awareness. Conclusion: Funded maternal vaccinations in pharmacies are generally well accepted and provide an opportunity to increase uptake and prevent disease.

Inequalities in maternal pertussis vaccination uptake: a cross-sectional survey of maternity units

Background

This study aims to estimate pertussis vaccine uptake in pregnant women in England, describe timing of vaccine delivery and examine variations in uptake.

Methods

Cross-sectional survey of vaccine uptake in women delivering in maternity units in England. Variation in uptake described according to geography, maternal age, ethnicity and parity as reported by the midwife completing the survey.

Results

A total of 1325 surveys were returned, 85% of which (1128) contained information about vaccination. Vaccine uptake was 61.8% (95% CI: 56.8-66.5) and was higher in the White British ethnic group than any other (67.7%, 95% CI: 63.5 to 71.5). Uptake was higher outside London (65.3%, 95% CI: 61.1-69.3) than within London (31.0%, 95% CI: 24.9-38.0). Reported uptake was lower in areas of high deprivation, and in women of higher parity, observations that were not statistically significant in the multivariable model. Overall, 74% of women were vaccinated between 28 and 32 weeks.

Conclusions

Pertussis vaccine uptake in pregnant women varies significantly across the country and is affected by ethnicity, deprivation and parity. Variations should be addressed through service delivery models designed to reduce potential inequalities in infant protection.

Impact of the adolescent pertussis booster dose on the incidence of pertussis in British Columbia and Quebec, Canada

Impact of an adolescent tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine program was assessed in the provinces of British Columbia and Quebec, Canada. In both provinces, the Tdap booster has been in place since 2004, targeting Grade 9 students (14-15-years-of-age). Incidence rate ratios (IRRs) standardizing notification rates among teens 15-19-years-old to infants <1-year-old decreased following introduction of the Tdap program and were significantly halved during the 2009-2012 post-Tdap versus 2000-2003 pre-Tdap period. This program impact, however, is tempered by the observation that pertussis incidence among 15-19-year-olds was already lower than any other pediatric age group, following gradual decline from pre-teen rates even before the Tdap program. The risk of hospitalization among adolescents 15-19-years-old was also low throughout at <1/100,000. Furthermore, IRRs increased in 2013-2017 when an increasing proportion of 15-19-year-olds were primed with acellular pertussis vaccine only, suggesting short-lived Tdap booster-dose effectiveness that warrants further monitoring.

Pertussis epidemiological pattern and disease burden in Brazil: an analysis of national public health surveillance data

Objective: We described pertussis epidemiological trends in Brazil between 2010 and 2015. We also assessed tetanus, diphtheria and acellular pertussis (Tdap) vaccine coverage among pregnant women from 2014, the year of the introduction of Tdap maternal immunization recommendation in Brazil, to 2016.Methods: Epidemiological data for incidence, prevalence, hospitalization, mortality, and maternal vaccination coverage were calculated based on the Brazilian public surveillance databases.Results: The epidemiological data analysis results showed that the pertussis average incidence rate (IR) was 2.19/100,000 inhabitants for all ages, with a peak in 2014 (4.03/100,000 inhabitants) and highest incidence in <1-year-old children (IR = 175.20/100,000). 97.6% of pertussis deaths (405/415) were in <1-year-old children. Maternal immunization coverage was 9.2% in 2014, 40.4% in 2015, and 33.8% in 2016.Conclusions: Pertussis incidence and pertussis-related deaths increased in Brazil from 2010 to 2014 and decreased in 2015. In the two years, 2015 and 2016 that followed the NIP recommendation, Tdap vaccination coverage of pregnant women was low and varying from region to region. More efforts and national plans would help increase awareness and maternal immunization coverage.

Acellular Pertussis Vaccine Effectiveness Over Time

OBJECTIVES

To determine pertussis risk by diphtheria-tetanus-acellular pertussis (DTaP) vaccination status and time since last DTaP dose.

METHODS

Children born at Kaiser Permanente Northern California between 1999 and 2016 were followed from 3 months of age until they tested positive for pertussis; disenrolled from Kaiser Permanente Northern California; received the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis, adsorbed vaccine; turned 11 years of age, or the end of the study period. DTaP vaccination status was categorized on the basis of the number of doses received in relation to the number of doses expected according to the Advisory Committee on Immunization Practice-recommended ages.

RESULTS

Among 469 982 children ages 3 months to 11 years, we identified 738 pertussis cases. A total of 99 cases were unvaccinated, 36 were undervaccinated, 515 were fully vaccinated, and 88 were fully vaccinated plus 1 dose. Pertussis risk was 13 times higher among unvaccinated (adjusted hazard ratio [aHR] = 13.53; 95% confidence interval [CI] 10.64-17.21) compared with fully vaccinated children and 1.9 times higher (aHR = 1.86; 95% CI 1.32-2.63) among undervaccinated children. Among vaccinated children ages 19 to <84 months, pertussis risk was 5 times higher (aHR = 5.04; 95% CI 1.84-13.80) ≥3 years vs <1 year after vaccination. Among children ages 84 to 132 months, risk was 2 times higher (aHR = 2.32; 95% CI 0.97-5.59) ≥6 years vs <3 years after vaccination.

CONCLUSIONS

Undervaccinated and especially unvaccinated children were at greater risk of pertussis. However, most pertussis cases occurred among children age-appropriately vaccinated who were further away from their last DTaP dose, suggesting that suboptimal vaccine effectiveness played a major role in recent pertussis epidemics.

Pertussis: New preventive strategies for an old disease

In the last twenty years, despite high vaccination coverage, epidemics of pertussis are occurring in both developing and developed countries. Many reasons could explain the pertussis resurgence: the increasing awareness of the disease, the availability of new diagnostic tests with higher sensitivity, the emergence of new Bordetella pertussis (B. pertussis) strains different from those contained in the current vaccines, the asymptomatic transmission of B. pertussis in adolescents and adults and the shorter duration of protection given by the acellular pertussis (aP) vaccine. New preventive strategies have already been implemented, such as booster doses of aP vaccine in adolescents and adults, maternal immunisation during pregnancy and the "cocooning" strategy, but more are still needed. Knowing what is new about this old disease is necessary to reduce its incidence and to protect infants too young to be vaccinated, which have the highest risk of complications and death.

Early-life predictors of future multi-morbidity: results from the Hertfordshire Cohort

Background

multi-morbidity is an increasing challenge in western medicine and has the potential to impact patients' quality of life, treatment options and compliance with medications. The aim of this study was to identify the early-life predictors of long-term multi-morbidity in an historical cohort, the Hertfordshire Cohort Study (HCS).

Methods

perinatal and infant health records were kept on all children born in Hertfordshire between 1931 and 1939. Participants who were still alive in 1998 were recruited to the HCS and data collected on major chronic diseases. They were subsequently followed up in the Clinical Outcomes Study (COS), and data recorded on all major illnesses since HCS, as well as current medications. Ordinal logistic regression analysed the association between early-life factors and the number of morbidities in these two surveys as well as medication count.

Results

a total of 2299 participants had data in COS, 1131 (49%) were female, median age (interquartile range) at recruitment to HCS was 66 (64-68) years. Higher rates of childhood illnesses were significantly associated with future multi-morbidity (multivariate odds ratio (OR) (95% confidence interval (CI)) 1.15 (1.06, 1.25)) and higher medication counts at COS (multivariate OR (95%CI) 1.14 (1.06, 1.23)).

Conclusions

children who experience more illnesses at a young age may be prone to develop multi-morbidity in later life.

Hospitalisation of preterm infants with pertussis in the context of a maternal vaccination programme in England

AIMS

To assess whether preterm infants are at increased risk of pertussis infection and whether this increased following introduction of a maternal pertussis vaccination in England, while examining characteristics of infants associated with more severe disease.

METHODS

Infants aged <60 days admitted between 1 April 2009 and 31 March 2016 with a pertussis diagnosis code were extracted from Hospital Episode Statistics (HES) data. HES data were reconciled with existing surveillance systems to capture maternal vaccination status where available. Cases were compared preimplementation and postimplementation of the maternal programme with respect to demography, preterm or full-term birth and coinfection. Survival analysis was undertaken to assess the impact of variables on duration of hospital stay.

RESULTS

The proportion of hospitalised preterm infants (138/1309, 10.6%) was higher than population estimates (7.4%), increasing from 9.8% (83/847) to 12.1% (56/462) following implementation of the maternal programme. Longer duration of hospital stay was associated with prematurity, younger age, additional respiratory illnesses and mothers unvaccinated in pregnancy. Of 13 deaths, 5 were preterm (38.5%) and 11 (84.6%) were female. A larger proportion of full-term infants' (49/188, 26.1%) mothers had been vaccinated in pregnancy than preterm infants (7/49, 14.3%), with 14.3% of mothers of full-term cases vaccinated after 35 weeks.

CONCLUSIONS

Preterm infants are over-represented in hospitalised pertussis cases and have less benefit from the maternal pertussis vaccination programme in England due to reduced opportunity for maternal vaccination.

Vaccination in pregnancy: Attitudes of nurses, midwives and health visitors in England

OBJECTIVE

To examine amongst healthcare professionals in England; knowledge of vaccinations in pregnancy, their perceived roles in these programmes and whether they recommend scheduled vaccines to pregnant women.

DESIGN

Cross sectional survey (online questionnaire) Setting: Healthcare workers in contact with pregnant women in England.

PARTICIPANTS

The survey analysis included 3441 healthcare workers who had been surveyed during May to August 2015. The participants were midwives, practice nurses and health visitors, working in England who were members of the Royal College of Midwives, Royal College of Nursing and the Institute of Health Visiting.

RESULTS

We found that knowledge of vaccination in pregnancy was high in all professional groups. Seventy three percent of all respondents would recommend the influenza vaccine and 74% would recommend the pertussis vaccine to pregnant women. They were more likely to recommend vaccination in pregnancy if they would personally have the influenza and pertussis vaccines themselves and/or if they had the influenza vaccine as a healthcare worker. Practice nurses were significantly more likely to recommend the pertussis and influenza vaccines to pregnant women than midwives and health visitors. Health professionals who had received immunisation training were more confident in giving advice to pregnant women.

CONCLUSION

Immunisation training is essential if healthcare workers are to be informed and confident in effectively delivering the maternal immunisation programme and thus improving uptake of vaccines in pregnancy. These findings are important in tailoring educational programmes and addressing the training needs of different healthcare professional groups.

Efficacy and safety of pertussis vaccination for pregnant women - a systematic review of randomised controlled trials and observational studies

BACKGROUND

Worldwide, pertussis remains a major health problem among children. During the recent outbreaks of pertussis, maternal antenatal immunisation was introduced in several industrial countries. This systematic review aimed to synthesize evidence for the efficacy and safety of the pertussis vaccination that was given to pregnant women to protect infants from pertussis infection.

METHODS

We searched literature in the Cochrane Central Register of Controlled Trials, Medline, Embase, and OpenGrey between inception of the various databases and 16 May 2016. The search terms included 'pertussis', 'whooping cough', 'pertussis vaccine,' 'tetanus, diphtheria and pertussis vaccines' and 'pregnancy' and 'perinatal'.

RESULTS

We included 15 articles in this review, which represented 12 study populations, involving a total of 203,835 mother-infant pairs from the US, the UK, Belgium, Israel, and Vietnam. Of the included studies, there were two randomised controlled trials (RCTs) and the rest were observational studies. Existing evidence suggests that vaccinations administered during 19-37 weeks of gestation are associated with significantly increased antibody levels in the blood of both mothers and their newborns at birth compared to placebo or no vaccination. However, there is a lack of robust evidence to suggest whether these increased antibodies can also reduce the incidence of pertussis (one RCT, n = 48, no incidence in either group) and pertussis-related severe complications (one observational study) or mortality (no study) in infants. Meanwhile, there is no evidence of increased risk of serious complications such as stillbirth (e.g. one RCT, n = 103, RR = 0, meaning no case in the vaccine group), or preterm birth (two RCTs, n = 151, RR = 0.86, 95%CI: 0.14-5.21) related to administration of the vaccine during pregnancy.

CONCLUSION

Given that pertussis infection is increasing in many countries and that newborn babies are at greatest risk of developing severe complications from pertussis, maternal vaccination in the later stages of pregnancy should continue to be supported while further research should fill knowledge gaps and strengthen evidence of its efficacy and safety.

Use of acellular pertussis vaccines in the United States: can we do better?

INTRODUCTION

Despite robust vaccination schedules and high vaccination rates, many countries, including the U.S., have seen large pertussis outbreaks with a shift in recent years in the distribution of disease burden towards adolescents and young adults. Areas covered: This perspective covers problems related to the increased incidence of pertussis among adolescents. Because the Tdap vaccine only protects against pertussis for 1-2 years after vaccination, we propose a new strategy which aims to optimize the benefit of Tdap in adolescents. Expert commentary: Current pertussis vaccination schedules are based on age and have not been effective at protecting adolescents and teenagers from pertussis outbreaks. An alternative to the current practice would be to take advantage of the cyclical nature of pertussis outbreaks. Rather than immunizing children and adolescent solely based on age regardless of risk of pertussis at that moment, perhaps we should consider a 'timed' Tdap. The goal would be to administer Tdap to susceptible adolescents and young adults during periods when there is a greater risk of being exposed to pertussis. This approach would optimize the use of an effective, but short-lived vaccine by maximizing protection at the time of increased risk.

A high seroprevalence of antibodies to pertussis toxin among Japanese adults: Qualitative and quantitative analyses

In 2013, national serosurveillance detected a high seroprevalence of antibodies to pertussis toxin (PT) from Bordetella pertussis among Japanese adults. Thus, we aimed to determine the cause(s) of this high seroprevalence, and analyzed the titers of antibodies to PT and filamentous hemagglutinin (FHA) among adults (35-44 years old), young children (4-7 years old), and older children (10-14 years old). Our quantitative analyses revealed that adults had higher seroprevalences of anti-PT IgG and PT-neutralizing antibodies, and similar titers of anti-FHA IgG, compared to the young and older children. Positive correlations were observed between the titers of PT-neutralizing antibodies and anti-PT IgG in all age groups (rs values of 0.326-0.522), although the correlation tended to decrease with age. The ratio of PT-neutralizing antibodies to anti-PT IgG was significantly different when we compared the serum and purified IgG fractions among adults (p = 0.016), although this result was not observed among young and older children. Thus, it appears that some adults had non-IgG immunoglobulins to PT. Our analyses also revealed that adults had high-avidity anti-PT IgG (avidity index: 63.5%, similar results were observed among the children); however, the adults had lower-avidity anti-FHA IgG (37.9%, p < 0.05). It is possible that low-avidity anti-FHA IgG is related to infection with other respiratory pathogens (e.g., Bordetella parapertussis, Haemophilus influenzae, or Mycoplasma pneumoniae), which produces antibodies to FHA-like proteins. Our observations suggest that these adults had been infected with B. pertussis and other pathogen(s) during their adulthood.

Increasing Incidence of Life-threatening Pertussis: A Retrospective Cohort Study in New Zealand

BACKGROUND

Pertussis immunization programs aim to prevent severe infant disease. We investigated temporal trends in infant pertussis deaths and pediatric intensive care unit (PICU) admissions and associations of changes in disease detection and vaccines used with death and PICU admission rates.

METHODS

Using national data from New Zealand (NZ), we described infant pertussis deaths and PICU admissions from 1991 to 2013, over which time national immunization coverage at 2 years of age increased from <80% to 92%. In NZ, pertussis became a notifiable disease with polymerase chain reaction (PCR) diagnosis available in 1997 and acellular replaced whole-cell vaccine in 2000. We used Poisson regression to model temporal trends and compared rates in time intervals using rate ratios (RRs) with 95% confidence intervals (CIs).

RESULTS

There were 10 pertussis deaths and 159 infant PICU admissions with pertussis from 1991 to 2013. The annual number of infant pertussis PICU admissions increased from 1991 to 2013 (P = 0.02) but the number of pertussis deaths did not (P = 0.09). The risk of PICU admission during infancy with pertussis was increased in the notification/PCR versus the non-notification/PCR era (RR: 1.12; 95% CI: 1.02-1.19) and when acellular replaced whole-cell vaccine (RR: 1.19; 95% CI: 1.06-1.31). Median Pediatric Index of Mortality scores during 2001-2013 were lower than during 1991-1999 (P < 0.001).

CONCLUSIONS

Infant PICU pertussis admission rates have increased in NZ despite improvements in immunization coverage. Higher rates have occurred since pertussis notification/PCR became available and since acellular replaced whole-cell vaccine. The severity of disease in infants admitted to PICU with pertussis has decreased in recent years.

Evaluation of a commercial loop-mediated isothermal amplification assay for diagnosis of Bordetella pertussis infection

We evaluated a commercial loop-mediated isothermal amplification (LAMP) assay kit for Bordetella pertussis detection. The LAMP primers were designed to target the ptxP1 allele of the pertussis toxin promoter, but the assay could detect B. pertussis ptxP3 and ptxP8 strains in addition to ptxP1 strains, with high analytical sensitivity.

Sustained Effectiveness of the Maternal Pertussis Immunization Program in England 3 Years Following Introduction

The effectiveness of maternal immunization in preventing infant pertussis was first demonstrated in England, 1 year after the program using diphtheria-tetanus-5-component acellular pertussis-inactivated polio vaccine (dT5aP-IPV) was introduced in 2012. Vaccine effectiveness against laboratory-confirmed pertussis has been sustained >90% in the 3 years following its introduction, despite changing to another acellular vaccine with different antigen composition. Consistent with this, disease incidence in infants <3 months of age has remained low despite high activity persisting in those aged 1 year and older. Vaccine effectiveness against infant deaths was estimated at 95% (95% confidence interval, 79%-100%). Additional protection from maternal immunization is retained in infants who received their first dose of the primary series. There is no longer evidence of additional protection from maternal vaccination after the third infant dose. Although numbers are small and ongoing assessment is required, there is no evidence of increased risk of disease after primary immunization in infants whose mothers received maternal vaccination.

Vaccine strategies: Optimising outcomes

Successful immunisation programmes generally result from high vaccine effectiveness and adequate uptake of vaccines. In the development of new vaccination strategies, the structure and strength of the local healthcare system is a key consideration. In high income countries, existing infrastructures are usually used, while in less developed countries, the capacity for introducing new vaccines may need to be strengthened, particularly for vaccines administered beyond early childhood, such as the measles or human papillomavirus (HPV) vaccine. Reliable immunisation service funding is another important factor and low income countries often need external supplementary sources of finance. Many regions also obtain support in generating an evidence base for vaccination via initiatives created by organisations including World Health Organization (WHO), the Pan American Health Organization (PAHO), the Agence de Médecine Préventive and the Sabin Vaccine Institute. Strong monitoring and surveillance mechanisms are also required. An example is the efficient and low-cost approaches for measuring the impact of the hepatitis B control initiative and evaluating achievement of goals that have been established in the WHO Western Pacific region. A review of implementation strategies reveals differing degrees of success. For example, in the Americas, PAHO advanced a measles-mumps-rubella vaccine strategy, targeting different population groups in mass, catch-up and follow-up vaccination campaigns. This has had much success but coverage data from some parts of the region suggest that children are still not receiving all appropriate vaccines, highlighting problems with local service infrastructures. Stark differences in coverage levels are also observed among high income countries, as is the case with HPV vaccine implementation in the USA versus the UK and Australia, reflecting differences in delivery settings. Experience and research have shown which vaccine strategies work well and the factors that encourage success, which often include strong support from government and healthcare organisations, as well as tailored, culturally-appropriate local approaches to optimise outcomes.

Highlights of the 11th International Bordetella Symposium: from Basic Biology to Vaccine Development

Pertussis is a severe respiratory disease caused by infection with the bacterial pathogen Bordetella pertussis The disease affects individuals of all ages but is particularly severe and sometimes fatal in unvaccinated young infants. Other Bordetella species cause diseases in humans, animals, and birds. Scientific, clinical, public health, vaccine company, and regulatory agency experts on these pathogens and diseases gathered in Buenos Aires, Argentina from 5 to 8 April 2016 for the 11th International Bordetella Symposium to discuss recent advances in our understanding of the biology of these organisms, the diseases they cause, and the development of new vaccines and other strategies to prevent these diseases. Highlights of the meeting included pertussis epidemiology in developing nations, genomic analysis of Bordetella biology and evolution, regulation of virulence factor expression, new model systems to study Bordetella biology and disease, effects of different vaccines on immune responses, maternal immunization as a strategy to prevent newborn disease, and novel vaccine development for pertussis. In addition, the group approved the formation of an International Bordetella Society to promote research and information exchange on bordetellae and to organize future meetings. A new Bordetella.org website will also be developed to facilitate these goals.

Pertussis in infants: an underestimated disease

BACKGROUND

The clinical diagnosis of pertussis is not easy in early infancy since clinical manifestations can overlap with several different diseases. Many cases are often misclassified and underdiagnosed. We conducted a retrospective study on infants to assess how often physicians suspected pertussis and the actual frequency of Bordetella pertussis infections.

METHODS

We analyzed all infants with age ≤90 days hospitalized from March 2011 until September 2013 for acute respiratory symptoms tested with a Real Time Polymerase Chain Reaction able to detect Bordetella pertussis and with a Real Time Polymerase Chain Reaction for a multipanel respiratory virus. Therefore, we compared patients with pertussis positive aspirate, patients with respiratory virus positive aspirate and patients with negative aspirate to identify symptoms or clinical findings predictive of pertussis.

RESULTS

Out of 215 patients analyzed, 53 were positive for pertussis (24.7 %), 119 were positive for respiratory virus (55.3 %) and 43 had a negative aspirate (20 %). Pertussis was suspected in 22 patients at admission and 16 of them were confirmed by laboratory tests, while 37 infants with different admission diagnosis resulted positive for pertussis. The sensitivity of clinical diagnosis was 30.2 % and the specificity 96.3 %. Infants with pertussis had more often paroxysmal cough, absence of fever and a higher absolute lymphocyte count than infants without pertussis.

CONCLUSIONS

Pertussis is a serious disease in infants and it is often unrecognized; some features should help pediatricians to suspect pertussis, but clinical suspicion has a low sensitivity. We suggest a systematic use of Real Time Polymerase Chain Reaction to support the clinical suspicion of pertussis in patients with less than 3 months of age hospitalized with acute respiratory symptoms.

Intention to Accept Pertussis Vaccination for Cocooning: A Qualitative Study of the Determinants

Context

Several countries have reported a resurgence of pertussis in the last decades. This puts infants (especially <6 months) at risk of severe complications, because they are too young to be fully protected by vaccination. The global pertussis initiative has proposed pertussis vaccination of young infants’ close contacts, in order to reduce pertussis transmission and the burden of the disease on infants. Our aim is to explore the perceived determinants (barriers and facilitators) of intention to accept vaccination among the possible target groups of pertussis vaccination for cocooning. Consideration of these determinants is necessary to optimise the uptake of the vaccination.

Methods

We conducted 13 focus groups and six individual semi-structured interviews with members of possible target groups for pertussis cocooning (i.e. parents, maternity assistants, midwives, and paediatric nurses) in the Netherlands. Here, both maternal pertussis vaccination as well as pertussis cocooning has not been implemented. The topic list was based on a literature review and a barrier framework. All interviews were transcribed verbatim and two researchers performed thematic content analysis.

Findings

The participants’ risk perception, outcome expectations, general vaccination beliefs, moral norms, opinion of others, perceived autonomy, anticipated regret, decisional uncertainty, and perceived organisational barriers were all factors that influenced the intention to accept pertussis vaccination for cocooning.

Discussion

This study has identified nine perceived determinants that influence the intention to accept pertussis cocooning vaccination. We add the following determinants to the literature: perceived cost-effectiveness (as a concept of outcome expectations), justice (as a concept of moral norms), anticipated regret, and decisional uncertainty. We recommend considering these determinants in vaccination programmes for pertussis cocooning vaccination. Experience, information and trust emerged as predominant themes within these determinants. These themes require particular attention in future research on vaccination acceptance, especially with regard to their role in use and implementation in policy and practice.

What timing of vaccination is potentially dangerous for children younger than 2 years?

Vaccine-preventable diseases still occur although measured coverage rates at 2 y of age are high. The occurrence of these diseases may be explained in part by untimely, that is, late vaccination. Our objective was to identify potentially dangerous vaccination delays for each dose of each vaccine in children younger than 2 y. A 3-round Delphi process was conducted by e-mail. We recruited 37 French experts in vaccines for children: 16 from the Infovac-France group and 21 from the French study group for pediatric infectious diseases. Items were generated by a literature review for the 10 vaccine doses recommended before 2 y of age. Item reduction in round 1 and 2 and any consensus in round 3 used a 70% consensus cutoff. The mean participation rate was 79%. Delays that should not be exceeded were identified for all vaccine doses. The 70% consensus was reached for 6 of the 10 vaccine doses: 15 d after the recommended date for the first 2 doses of the diphtheria-tetanus-acellular pertussis-inactivated polio vaccine/Haemophilus influenzae b vaccine and for the second dose of the pneumococcal conjugate vaccine, 1 month for the meningococcal C vaccine and for the first dose of the measles-mumps-rubella vaccine, and 11 y of age for completion of the hepatitis B vaccination. This Delphi process identified potentially dangerous vaccination delays for children to the age of 2 y. These can be used as new indicators in further studies of vaccine effectiveness and can help to improve the quality of vaccine protection in children.

A population profile of measles susceptibility in Tianjin, China

BACKGROUND

Measles is a highly infectious illness requiring herd immunity of 95% to interrupt transmission. Measles is targeted for elimination in China, which has not reached elimination goals despite high vaccination coverage. We developed a population profile of measles immunity among residents aged 0-49 years in Tianjin, China.

METHODS

Participants were either from community population registers or community immunization records. Measles IgG antibody status was assessed using dried blood spots. We examined the association between measles IgG antibody status and independent variables including urbanicity, sex, vaccination, measles history, and age.

RESULTS

2818 people were enrolled. The proportion measles IgG negative increased from 50.7% for infants aged 1 month to 98.3% for those aged 7 months. After 8 months, the age of vaccination eligibility, the proportion of infants and children measles IgG negative decreased. Overall, 7.8% of participants 9 months of age or older lacked measles immunity including over 10% of those 20-39 years. Age and vaccination status were significantly associated with measles IgG status in the multivariable model. The odds of positive IgG status were 0.337 times as high for unvaccinated compared to vaccinated (95% CI: 0.217, 0.524).

CONCLUSIONS

The proportion of persons in Tianjin, China immune to measles was lower than herd immunity threshold with less than 90% of people aged 20-39 years demonstrating protection. Immunization programs in Tianjin have been successful in vaccinating younger age groups although high immunization coverage in infants and children alone would not provide protective herd immunity, given the large proportion of non-immune adults.

Waning Tdap Effectiveness in Adolescents

BACKGROUND AND OBJECTIVE

Because the effectiveness of diphtheria-tetanus-acellular pertussis (DTaP) vaccine wanes substantially after the fifth dose at ages 4 to 6 years, there is a growing cohort of adolescents who rely on tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) for protection against pertussis. Yet despite high Tdap vaccine coverage among adolescents, California experienced large pertussis outbreaks in 2010 and 2014. We investigated Tdap vaccine effectiveness (VE) and waning within Kaiser Permanente Northern California among adolescents exclusively vaccinated with DTaP vaccines.

METHODS

We modeled pertussis risk in relation to Tdap vaccination status among adolescents beginning on their 10th birthday. We estimated the hazard ratio (HR) for each subsequent year after Tdap compared with unvaccinated adolescents by using Cox regression, adjusting for calendar time, age, gender, race, and facility. We calculated VE as 1 - HR. We also treated time since Tdap vaccination as a continuous variable and estimated the change in the HR per 1-year increase since vaccination.

RESULTS

On the basis of 1207 pertussis cases, Tdap VE during the first year after vaccination was 68.8% (95% confidence interval [CI] 59.7% to 75.9%), decreasing to 8.9% (95% CI -30.6% to 36.4%) by ≥4 years after vaccination. Adolescents who were more remote from Tdap were significantly more likely to test positive for pertussis than were those vaccinated more recently (HR per year 1.35, 95% CI 1.22 to 1.50).

CONCLUSIONS

Routine Tdap did not prevent pertussis outbreaks. Among adolescents who have only received DTaP vaccines in childhood, Tdap provided moderate protection against pertussis during the first year and then waned rapidly so that litle protection remained 2-3 years after vaccination..

Bordetella pertussis epidemiology and evolution in the light of pertussis resurgence

Whooping cough, or pertussis, is resurgent in many countries world-wide. This is linked to switching from the use of whole cell vaccines to acellular vaccines in developed countries. Current evidence suggests that this has resulted in the earlier waning of vaccine-induced immunity, an increase in asymptomatic infection with concomitant increases in transmission and increased selection pressure for Bordetellapertussis variants that are better able to evade vaccine-mediated immunity than older isolates. This review discusses recent findings in B. pertussis epidemiology and evolution in the light of pertussis resurgence, and highlights the important role for genomics-based studies in monitoring B. pertussis adaptation.

What to do about pertussis vaccines? Linking what we know about pertussis vaccine effectiveness, immunology and disease transmission to create a better vaccine

Pertussis (whooping cough) is a respiratory disease caused by the bacterium Bordetella pertussis. Despite the implementation of immunization programs and high vaccine coverage in most jurisdictions, pertussis is still one of the most common vaccine-preventable diseases, suggesting that the current vaccines and immunization schedules have not been sufficiently effective. Several factors are thought to contribute to this. The acellular pertussis vaccine that has been used in many jurisdictions since the 1990s is less effective than the previously used whole-cell vaccine, with immunity waning over time. Both whole-cell and acellular pertussis vaccines are effective at reducing disease severity but not transmission, resulting in outbreaks in vaccinated cohorts. In this review, we discuss various limitations of the current approaches to protection from pertussis and outline various options for reducing the burden of pertussis on a population level.