Potential strategies to reduce the burden of pertussis

Attack Rate, Case Fatality Rate and Predictors of Pertussis Outbreak During Pertussis Outbreak Investigation in Ethiopia: Systematic Review and Meta-Analysis

BACKGROUND

Pertussis, a highly contagious, vaccine-preventable respiratory infection caused by Bordetella pertussis, is a leading global public health issue. Ethiopia is currently conducting multiple pertussis outbreak investigations, but there is a lack of comprehensive information on attack rate, case fatality rate, and infection predictors. This study aimed to measure attack rates, case fatality rates, and factors associated with pertussis outbreak.

METHODS

This study conducted a systematic review and meta-analysis of published and unpublished studies on pertussis outbreaks in Ethiopia from 2009 to 2023, using observational study designs, using the guideline Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The study utilized databases like Science Direct, MEDLINE/PubMed, African Journals Online, Google Scholar and registers. The data were collected using an Excel Spreadsheet and then exported to STATA version 17 for analysis. Subgroup analysis was conducted to identify potential disparities. A random effects model was used to consider heterogeneity among studies. I2-squared test statistics were used to assess heterogeneity. The attack rate, case fatality rate, and odds ratio (OR) were presented using forest plots with a 95% confidence interval. Egger's and Begg's tests were used to evaluate the publication bias.

RESULTS

Seven pertussis outbreak investigations with a total of 2824 cases and 18 deaths were incorporated. The pooled attack and case fatality rates were 10.78 (95% CI: 8.1-13.5) per 1000 population and 0.8% (95% CI: 0.01-1.58%), respectively. The highest and lowest attack rates were in Oromia (5.57 per 1000 population and in the Amhara region (2.61 per 1000 population), respectively. Predictor of pertussis outbreak were being unvaccinated [odds ratio (OR) = 3.05, 95% CI: 1.83-4.27] and contact history [OR = 3.44, 95% CI: 1.69-5.19].

CONCLUSION

Higher and notable variations in attack and case fatality rates were reported. Being unvaccinated and having contact history were the predictors of contracting pertussis disease in Ethiopia. Enhancing routine vaccination and contact tracing efforts should be strengthened.

Improving Tdap maternal immunization rate in Saudi Arabia

Pertussis is a serious and potentially fatal disease in infants too young for vaccination. Despite a high vaccine coverage in children, pertussis continues to occur in unvaccinated infants in the Kingdom of Saudi Arabia (KSA). Available data supports the use of maternal pertussis immunization for preventing pertussis in young infants. In June 2019, the Saudi Ministry of Health recommended maternal pertussis immunization with combined tetanus-diphtheria-acellular pertussis vaccine (Tdap) during every pregnancy. To understand barriers to maternal immunization and identify strategies to improve maternal immunization, we conducted an online survey in November and December 2020, asking 60 obstetricians/gynecologists about their attitudes to maternal pertussis immunization. Fewer than 50% survey respondents considered maternal immunization as part of their role, and only 47% were aware of the national recommendation. Consequently, the uptake of maternal vaccination in KSA may be sub-optimal. The key barriers that hinder obstetricians/gynecologists from recommending maternal Tdap immunization were the anticipation of patient refusal, and their own need for more information/experience about the disease and the national recommendation. Vaccine availability and supply were important barriers, whereas cost/reimbursement and resource issues were of lesser concern. Disseminating evidence based information to physicians, educating pregnant women and addressing public misconceptions.

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

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

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

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

Vaccination information fathers receive during pregnancy and determinants of infant vaccination timeliness

The information fathers receive about infant vaccination may influence their decision to vaccinate. We describe fathers' sources of vaccination information and paternal determinants of timely infant vaccinations. Participants were from a child cohort study in New Zealand. The child cohort was established by enrolling pregnant women and their partners. During pregnancy, fathers (n = 4017) of the cohort children born 2009-2010 described information sources that encouraged or discouraged infant vaccination. The National Immunization Register provided infant vaccination data. Independent associations of the vaccination information received by fathers with the timeliness of their infant's vaccination were determined using multivariable logistic regression. Associations were described using adjusted odds ratios and 95% confidence intervals. One-third of fathers (1430/4017 [36%]) recalled receiving vaccination information, 64% of which encouraged vaccination. Most infants (2900/4017 [72%]) received all their vaccinations on time, however only 58% of Māori infants were vaccinated on time. Paternal determinants of vaccination timeliness were the father receiving discouraging or conflicting information about vaccination, father's ethnicity, father's vaccination hesitancy, and whether the mother received vaccination information. To improve vaccination uptake and timeliness, a vaccination conversation with mothers, fathers and whānau could be included in routine antenatal care, informing and supporting decision-making, and addressing concerns. Vaccination education should address present and historic distrust of the health system. Framing vaccination within a Māori model of health and including fathers and whānau in decision-making will address vaccination inequities in New Zealand.

The problem of pertussis in some regions of the world

Pertussis infection remains a high-priority issue both for Russian health care and abroad. A rise of pertussis incidence in various human age groups instigates a search for new ways to fight this infection and improve methods for its laboratory diagnostics. By taking into consideration a short-term effect induced by acellular and whole-cell vaccines, a feasibility of introducing the second or even the third pertussis revaccination is vigorously debated. Objective of the study was to analyze the experience and effectiveness of acellular pertussis vaccines in countries, which use the second and third pertussis revaccination in the National Immunization Schedule in order to have an insight into adjusting strategy and tactics of pertussis immunization In Russia. Analyzing pertussis prevalence demonstrated that despite a wide immunization coverage pertussis incidence in the last years (2008–2015) was increased in a large number of countries in the European region, as well as inAustralia,CanadaandUSA. However, the reasons for elevated pertussis incidence have not been clarified yet. On one hand, it may be accounted for by low vaccination coverage in adolescents and adults; weakened immune protection after vaccination; genetic changes in Bordetella pertussis; shortened durability of protective immunity in children vaccinated with acellular vs. whole-cell vaccine; improved monitoring and morbidity reporting, as well as improved laboratory diagnostics due to shifting from serological and bacteriological to molecular genetic assays. In an attempt to solve this issue, researchers from several countries collaborate to discuss and develop a strategy to reduce pertussis incidence. ForRussia, the most important is to empower and/or improve existing infant immunization strategy in order to provide wide coverage with the four dose pertussis vaccine for decreasing the risk of pertussis morbidity and mortality. It is worth noting the “cocoon” strategy given the high risk of pertussis infection in children of the first months of life. We believe that forRussiait is worth investigating an opportunity of using children 2–3 months of life an acellular vaccine as the first vaccination, which is expected to increase the coverage of this cohort and allow to increase proportion of children who might complete vaccination by 5 months of age. At the same time, more reasonable might be to preserve a number of age groups for pertussis vaccination in the current National Immunization Schedule, as expanding age limits for vaccination might put a risk at increasing pertussis morbidity in older individuals, which could be hard to diagnose. 

Reduction of Direct Health Costs Associated with Pertussis Vaccination with Acellular Vaccines in Children Aged 0-9 Years with Pertussis in Catalonia (Spain)

OBJECTIVES

The aim of this study was to assess direct health costs in children with pertussis aged 0-9 years who were vaccinated, partially vaccinated, and unvaccinated during childhood, and to assess the association between pertussis costs and pertussis vaccination in Catalonia (Spain) in 2012-2013.

METHODS

Direct healthcare costs included pertussis treatment, pertussis detection, and preventive chemotherapy of contacts. Pertussis patients were considered vaccinated when they had received 4-5 doses, and unvaccinated or partially vaccinated when they had received 0-3 doses of vaccine. The Chi square test and the odds ratios were used to compare percentages and the t test was used to compare mean pertussis costs in different groups, considering a p < 0.05 as statistically significant. The correlation between pertussis costs and study variables was assessed using the Spearman's ρ, with a p < 0.05 as statistically significant. Multiple linear regression analysis (IBM-SPSS program) was used to quantify the association of pertussis vaccination and other study variables with pertussis costs.

RESULTS

Vaccinated children with pertussis aged 0-9 years had significantly lower odds ratios of hospitalizations (OR 0.02, p < 0.001), laboratory confirmation (OR 0.21, p < 0.001), and severe disease (OR 0.02, p < 0.001) than unvaccinated or partially vaccinated children with pertussis of the same age. Mean direct healthcare costs were significantly lower (p < 0.001) in vaccinated patients (€190.6) than in unvaccinated patients (€3550.8), partially vaccinated patients (€1116.9), and unvaccinated/partially vaccinated patients (€2330). Multivariable linear regression analysis showed that pertussis vaccination with 4-5 doses was associated with a non-significant reduction of pertussis costs of €107.9 per case after taking into account the effect of other study variables, and €200 per case after taking into account pertussis severity.

CONCLUSIONS

Direct healthcare costs were lower in children with pertussis aged 0-9 years vaccinated with 4-5 doses of acellular vaccines than in unvaccinated or partially vaccinated children with pertussis of the same age.

Vaccine Education During Pregnancy and Timeliness of Infant Immunization

OBJECTIVES

Pregnant women routinely receive information in support of or opposing infant immunization. We aimed to describe immunization information sources of future mothers' and determine if receiving immunization information is associated with infant immunization timeliness.

METHODS

We analyzed data from a child cohort born 2009-2010 in New Zealand. Pregnant women (N = 6822) at a median gestation of 39 weeks described sources of information encouraging or discouraging infant immunization. Immunizations received by cohort infants were determined through linkage with the National Immunization Register (n = 6682 of 6853 [98%]). Independent associations of immunization information received with immunization timeliness were described by using adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Immunization information sources were described by 6182 of 6822 (91%) women. Of these, 2416 (39%) received information encouraging immunization, 846 (14%) received discouraging information, and 565 (9%) received both encouraging and discouraging information. Compared with infants of women who received no immunization information (71% immunized on-time), infants of women who received discouraging information only (57% immunized on time, OR = 0.49, 95% CI 0.38-0.64) or encouraging and discouraging information (61% immunized on time, OR = 0.51, 95% CI 0.42-0.63) were at decreased odds of receiving all immunizations on time. Receipt of encouraging information only was not associated with infant immunization timeliness (73% immunized on time, OR = 1.00, 95% CI 0.87-1.15).

CONCLUSIONS

Receipt, during pregnancy, of information against immunization was associated with delayed infant immunization regardless of receipt of information supporting immunization. In contrast, receipt of encouraging information is not associated with infant immunization timeliness.

Pertussis: Microbiology, Disease, Treatment, and Prevention

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

Immunization against pertussis in adolescents and adults

Pertussis is a highly contagious infectious disease caused by Bordetella pertussis that can be extremely serious, particularly in young infants. For many years the efforts of health authorities throughout the world to prevent pertussis had the main goals of reducing the morbidity of infants and children under 5 years of age, maintaining protection for several years during the school-age period and developing a significant herd immunity to directly and indirectly reduce the risk of the spread of the disease among young infants and the risk of transmission of the infection from preschool children to infants. However, the increased risk of B. pertussis infection among adolescents and adults due to the waning immunity to this bacterium induced by vaccines and natural infection seems to be the main reason for the resurgence of pertussis. We discuss the reasons for the administration of pertussis vaccines to individuals for whom they were previously not recommended, the expected results of the administration of additional pertussis vaccine doses and the differences in the administration of pertussis vaccines in different countries. An analysis of the literature revealed several reports indicating the need for the modification of immunization schedules against pertussis, with booster doses among adolescents and the need for the vaccination of pregnant women. However, to monitor the true epidemiology of pertussis, effective programmes to collect pertussis cases, adequate reporting systems and vaccination coverage monitoring should be urgently implemented.

Antenatal immunisation intentions of expectant parents: Relationship to immunisation timeliness during infancy

BACKGROUND

Most women decide about infant immunisation during pregnancy. However, we have limited knowledge of the immunisation intentions of their partners. We aimed to describe what pregnant women and their partners intended for their future child's immunisations, and to identify associations between parental intentions and the subsequent timeliness of infant immunisation.

METHODS

We recruited a cohort of pregnant New Zealand (NZ) women expecting to deliver between April 2009 and March 2010. The cohort included 11% of births in NZ during the recruitment period and was generalisable to the national birth cohort. We completed antenatal interviews independently with mothers and partners. We determined immunisation receipt from the National Immunisation Register and defined timely immunisation as receiving all vaccines (scheduled at 6-weeks, 3- and 5-months) within 30 days of their due date. We described independent associations of immunisation intentions with timeliness using adjusted odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Of 6172 women, 5014 (81%) intended full immunisation, 245 (4%) partial immunisation, 140 (2%) no immunisation and 773 (13%) were undecided. Of 4152 partners, 2942 (71%) intended full immunisation, 208 (5%) partial immunisation, 83 (2%) no immunisation and 921 (22%) were undecided. Agreement between mothers and partners was moderate (Kappa=0.42). Timely immunisation occurred in 70% of infants. Independent of their partner's intentions, infants of pregnant women who decided upon full immunisation were more likely to be immunised on time (OR=7.65, 95% CI: 4.87-12.18). Independent of the future mother's intentions, infants of partners who had decided upon full immunisations were more likely to be immunised on time (OR=3.33, 95% CI: 2.29-4.84).

CONCLUSIONS

During pregnancy, most future parents intend to fully immunise their child; however, more partners than mothers remain undecided about immunisation. Both future mothers' and future fathers' intentions are independently associated with the timeliness of their infant's immunisations.

Predicting future trends in the burden of pertussis in the 21st century: implications for infant pertussis and the success of maternal immunization

Support is growing for maternal immunization using acellular pertussis (aP) vaccines to prevent severe pertussis disease and deaths among very young, unvaccinated infants. Vaccine effectiveness of maternal immunization is 91% in preventing laboratory-confirmed pertussis in infants aged <3 months. To date, most mothers were primed in childhood with whole-cell pertussis vaccines. Soon, the generation of aP-primed individuals will become the new mothers-to-be. The shorter duration of protection afforded by aP vaccines, which is more pronounced with repeated aP boosters, may lead to increased pertussis circulation among aP-primed parents. Maternal Tdap immunization in aP-primed mothers-to-be may become less effective. Additional measures to protect young infants may eventually be needed, along with new vaccines that induce higher quality and more durable responses.

Immunogenicity and reactogenicity of a decennial booster dose of a combined reduced-antigen-content diphtheria-tetanus-acellular pertussis and inactivated poliovirus booster vaccine (dTpa-IPV) in healthy adults

BACKGROUND

Pertussis in adults and adolescents could be reduced by replacing traditional tetanus and diphtheria (Td) boosters with reduced-antigen-content diphtheria-tetanus-acellular pertussis (dTpa) vaccines. This study evaluated the administration of dTpa-IPV (dTpa-inactivated poliovirus) in adults ten years after they received a booster dose of either dTpa-IPV, dTpa+IPV or Td-IPV in trial NCT01277705.

METHODS

Open multicentre, phase IV study (www.clinicaltrials.govNCT01323959) in which healthy adults, who had received a previous dose of dTpa-IPV, dTpa+IPV or Td-IPV ten years earlier, received a single decennial booster dose of dTpa-IPV (Boostrix-polio, GlaxoSmithKline Vaccines). Blood samples were collected before and one month after booster vaccination. Antibody concentrations against all vaccine antigens were measured and reactogenicity and safety were assessed.

RESULTS

A total of 211 subjects (mean age 50.3 years) received vaccination of whom 201 were included in the according-to-protocol cohort for immunogenicity. Before the decennial dTpa-IPV booster, ≥71.0% subjects were seroprotected/seropositive against all vaccine antigens. One month after the booster dose, all subjects were seroprotected against tetanus and poliovirus types 2 and 3; ≥95.7% subjects were seroprotected against diphtheria and ≥98.3% against poliovirus type 1. Anti-pertussis booster responses for the various antigens were observed in ≥76.5% (pertussis toxoid; PT), ≥85.1% (filamentous haemagglutinin; FHA) and ≥63.2% (pertactin; PRN) of subjects. During the 4-day follow-up, the overall incidence of local AEs was 71.6%, 75.0% and 72.2% in dTpa-IPV, dTpa+IPV and Td-IPV groups, respectively. Pain was the most frequent solicited local adverse event (AE; ≥62.7% subjects) and fatigue the most frequent solicited general AE (≥18.5%). No serious AEs were reported during the study.

CONCLUSION

A booster dose of dTpa-IPV was immunogenic and well tolerated in adults who had received a booster dose of either dTpa-IPV, dTpa+IPV or Td-IPV, ten years previously and supports the repeated administration of dTpa-IPV.

Evaluation of reported cases of pertussis: epidemiological study in a large city in Spain

We retrospectively analysed the incidence rate of reported cases of pertussis in Barcelona during 2009–2012 according to age, sex, type of medical centre and vaccination status. We included 748 confirmed or suspected cases, 613 (82.0 %) of which were confirmed by laboratory testing and the remaining 135 (18.0 %) by epidemiological evidence. The highest reported incidence of pertussis was amongst <1 year olds [96.1 per 100 000 person-years, 95 % confidence interval (CI): 84.3–109.1]. The majority of confirmed and suspected cases were reported in 2011 and 2012, and the total incidence (confirmed or suspected) was 6.3 (95 % CI: 5.6–6.9) and 4.2 (95 % CI: 3.6–4.7) per 100 000 person-years, respectively. Incidence increased significantly (P = 0.001) in 2011–2012 compared with 2009. Most confirmed cases occurred in children <1 year old (87.9 %). Cases were confirmed by real-time (RT)-PCR (87.5 %; 95 % CI: 81.3–87.6) and bacterial culture (13.7 %; 95 % CI: 11.0–17.1). We recommend performing RT-PCR in suspected cases with no epidemiological link to a confirmed case.

Symptomatic treatment of the cough in whooping cough

BACKGROUND

Around 16 million cases of whooping cough (pertussis) occur worldwide each year, mostly in low-income countries. Much of the morbidity of whooping cough in children and adults is due to the effects of the paroxysmal cough. Cough treatments proposed include corticosteroids, beta2-adrenergic agonists, pertussis-specific immunoglobulin, antihistamines and possibly leukotriene receptor antagonists (LTRAs).

OBJECTIVES

To assess the effectiveness and safety of interventions to reduce the severity of paroxysmal cough in whooping cough in children and adults.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL, 2014, Issue 1), which contains the Cochrane Acute Respiratory Infections Group's Specialised Register, the Database of Abstracts of Reviews of Effects (DARE 2014, Issue 2), accessed from The Cochrane Library, MEDLINE (1950 to 30 January 2014), EMBASE (1980 to 30 January 2014), AMED (1985 to 30 January 2014), CINAHL (1980 to 30 January 2014) and LILACS (30 January 2014). We searched Current Controlled Trials to identify trials in progress.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) and quasi-RCTs of any intervention (excluding antibiotics and vaccines) to suppress the cough in whooping cough.

DATA COLLECTION AND ANALYSIS

Two review authors (SB, MT) independently selected trials, extracted data and assessed the quality of each trial for this review in 2009. Two review authors (SB, KW) independently reviewed additional studies identified by the updated searches in 2012 and 2014. The primary outcome was frequency of paroxysms of coughing. Secondary outcomes were frequency of vomiting, frequency of whoop, frequency of cyanosis (turning blue), development of serious complications, mortality from any cause, side effects due to medication, admission to hospital and duration of hospital stay. 

MAIN RESULTS

We included 12 trials of varying sample sizes (N = 9 to 135), mainly from high-income countries, including a total of 578 participants. Ten trials recruited children (N = 448 participants). Two trials recruited adolescents and adults (N = 130 participants). We considered only three trials to be of high methodological quality (one trial each of diphenhydramine, pertussis immunoglobulin and montelukast). Included studies did not show a statistically significant benefit for any of the interventions. Only six trials, including a total of 196 participants, reported data in sufficient detail for analysis. Diphenhydramine did not change coughing episodes; the mean difference (MD) of coughing spells per 24 hours was 1.9; 95% confidence interval (CI) -4.7 to 8.5 (N = 49 participants from one trial). One trial on pertussis immunoglobulin reported a possible mean reduction of -3.1 whoops per 24 hours (95% CI -6.2 to 0.02, N = 47 participants) but no change in hospital stay (MD -0.7 days; 95% CI -3.8 to 2.4, N = 46 participants). Dexamethasone did not show a clear decrease in length of hospital stay (MD -3.5 days; 95% CI -15.3 to 8.4, N = 11 participants from one trial) and salbutamol showed no change in coughing paroxysms per day (MD -0.2; 95% CI -4.1 to 3.7, N = 42 participants from two trials). Only one trial comparing pertussis immunoglobulin versus placebo (N = 47 participants) reported data on adverse events: 4.3% in the treatment group (rash) versus 5.3% in the placebo group (loose stools, pain and swelling at injection site).

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw conclusions about the effectiveness of interventions for the cough in whooping cough. More high-quality trials are needed to assess the effectiveness of potential antitussive treatments in patients with whooping cough.

Pertussis seroprevalence in korean adolescents and adults using anti-pertussis toxin immunoglobulin G

This study was conducted to evaluate age-specific seroprevalence of pertussis in Korea and to formulate a strategy to prevent and reduce the incidence of pertussis. Residual serum samples of healthy adolescents and adults 11 yr of age or older were collected between July 2012 and December 2012, and anti-pertussis toxin (PT) IgG titers were measured using a commercial ELISA kit. We compared the mean anti-PT IgG titers and seroprevalence of pertussis of the six age groups: 11-20, 21-30, 31-40, 41-50, 51-60, and ≥ 61 yr. A total of 1,192 subjects were enrolled. The mean anti-PT IgG titer and pertussis seroprevalence were 35.53 ± 62.91 EU/mL and 41.4%, respectively. The mean anti-PT IgG titers and seroprevalence were not significantly different between the age groups. However, the seroprevalence in individuals 51 yr of age or older was significantly higher than in individuals younger than 51 yr (46.5% vs 39.1%, P = 0.017). Based on these results, a new pertussis prevention strategy is necessary for older adults.

A cross sectional survey of attitudes, awareness and uptake of the parental pertussis booster vaccine as part of a cocooning strategy, Victoria, Australia

Background

The Victorian Government Department of Health funded a diphtheria, tetanus and acellular pertussis vaccine for parents of infants from June 2009 to June 2012 as part of a cocooning strategy for the control of pertussis. The aim of this study was to assess parents’ attitudes and awareness of the vaccination program, and to estimate vaccine uptake.

Methods

A cross-sectional survey of 253 families with a child born in the first quarter of 2010 residing within five metropolitan and four rural local government areas in Victoria was conducted. Univariate analyses were performed to describe the relationship between demographic variables, knowledge and awareness of the disease, the vaccine program and vaccine uptake. Multivariate analyses examining predictors for awareness of the vaccine program and for the uptake of vaccination were also conducted.

Results

One hundred and five families were surveyed (response rate 43%). Of these, 93% indicated that they had heard of ‘pertussis’ or ‘whooping cough’ and 75% of mothers and 69% of fathers were aware the pertussis vaccine was available and funded for new parents. Overall, 70% of mothers and 53% of fathers were vaccinated following their child’s birth, with metropolitan fathers less likely to be vaccinated as rural fathers (RR = 0.6, p = 0.002). Being a younger mother (p = 0.02) or father (p = 0.047), and being an Australian-born father (RR = 1.9, p = 0.03) were found to predict uptake of the vaccine in parents.

Conclusion

Parents indicated a reasonable level of knowledge of pertussis and a willingness to be vaccinated to protect their child. However, vaccine uptake estimates indicated further opportunity for program improvement. Future cocooning strategies would benefit from specifically targeting fathers and metropolitan maternity hospitals to increase vaccine uptake. Wider promotion of the availability of vaccine providers may increase uptake to maximise the success of cocooning programs. Further investigation of the effectiveness of the cocooning strategy in decreasing infant morbidity and mortality is required.

Epidemiological and immunological reasons for pertussis vaccination in adolescents and adults

The resurgence of pertussis has been the subject of considerable debate. Hypotheses to explain increased reporting in developed countries have focused mainly on three aspects: (1) increased recognition of the disease in adolescents and adults; (2) waning of vaccine-induced immunity and (3) loss of vaccine efficacy due to an antigenic shift of Bordetella pertussis. Waning immunity after vaccination or natural infection combined with the absence of regular boosters either in the form of vaccine boosters or natural exposure to B. pertussis - due to the low circulation of the bacterium in well-immunized populations - has been suggested to explain this shift in the age distribution of pertussis. The highest incidence of the disease is currently reported among adolescents and adults who may additionally serve as the source of infection for susceptible infants. Immunological and epidemiological data indicates the need for a universal booster vaccination against pertussis for adolescents and adults.

The seroepidemiology of immunoglobulin G antibodies against pertussis toxin in China: a cross sectional study

Background

Pertussis is a reported vaccine-preventable respiratory disease in China. Because the routine laboratory methods for diagnosis are not in use, the reported cases are mainly in infants with classical paroxysmal cough and the true incidence related to pertussis is most likely under estimated. In China, however, few studies have attempted to address this issue. The purpose of this cross sectional study was to estimate the incidence rates using the method of sero-epidemiology of immunoglobulin (Ig) G antibodies against pertussis toxin (PT) among healthy populations in China.

Methods

Blood samples were obtained from 1313 healthy individuals aged 0 to 95 years in Guangdong province of China throughout September 2010. Serum IgG antibodies against PT were determined by commercial ELISA kits. Subjects with concentration of anti-PT IgG higher than 30 IU/mL were indicated to have recent Bordetella pertussis infection, if they have not received a booster dose of pertussis vaccine within one year.

Results

Of the 1313 study subjects, 117 (8.91%) were found to have anti-PT antibodies higher than 30 IU/mL. The estimated incidence of recent infection was thus 9395 per 100,000 for individuals older than 7 years. Peaks of the estimated incidence rate of recent infection were found to be 11561 per 100,000 in age group of 41–50 years and 11428 per 100,000 in the group aged 13–19 years.

Conclusions

Our study indicated that B.pertussis infections are considerablely common, particularly in adolescents and adults in China. The study also stresses the importance of laboratory diagnosis for pertussis and employment of booster dose of pertussis vaccine in adolescents and adults in this country.

Seroprevalence of pertussis in The Netherlands: evidence for increased circulation of Bordetella pertussis

BACKGROUND

In many countries, the reported pertussis has increased despite high vaccination coverage. However, accurate determination of the burden of disease is hampered by reporting artifacts. The infection frequency is more reliably estimated on the basis of the prevalence of high IgG concentrations against pertussis toxin (IgG-Ptx). We determined whether the increase in reported pertussis in the last decade is associated with an increase in the number of infections.

METHODOLOGY/PRINCIPAL FINDINGS

In a cross-sectional population-based serosurveillance study conducted in 2006-07, from a randomly selected age-stratified sample of 7,903 persons, serum IgG-Ptx concentrations were analyzed using a fluorescent bead-based multiplex immuno assay. In 2006-07, 9.3% (95%CI 8.5-10.1) of the population above 9 years of age had an IgG-Ptx concentration above 62.5 EU/ml (suggestive for pertussis infection in the past year), which was more than double compared to 1995-96 (4.0%; 95%CI 3.3-4.7). The reported incidence showed a similar increase as the seroprevalence between both periods.

CONCLUSIONS

Although changes in the vaccination program have reduced pertussis morbidity in childhood, they have not affected the increased infection rate in adolescent and adult pertussis. Indeed, the high circulation of B. pertussis in the latter age-categories may limit the effectiveness of pediatric vaccination.

Pertussis-the case for universal vaccination

PURPOSE

Does the literature support universal vaccination of adolescents and adults, reducing disease incidence in infants and young children?

DESIGN & METHODS

An extensive literature review and a meta-analysis of four case-control studies, evaluating effects of missed or late vaccine doses, was conducted.

RESULTS

The literature confirms (a) increasing pertussis rates; (b) adults and adolescents are the primary carriers; (c) vaccine effectiveness wanes over time; and (d) pertussis persists despite disease control efforts.

PRACTICE IMPLICATIONS

Missed or late doses mean an increase in likelihood of contracting pertussis, supporting full vaccination for children and boosters for adolescents/adults.

Dose response of attenuated Bordetella pertussis BPZE1-induced protection in mice

Despite the availability of efficacious vaccines, the incidence of whooping cough is still high in many countries and is even increasing in countries with high vaccine coverage. Most severe and life-threatening pertussis cases occur in infants who are too young to be sufficiently protected by current vaccine regimens. As a potential solution to this problem, we have developed an attenuated live Bordetella pertussis vaccine strain, named BPZE1. Here, we show that after a single administration, BPZE1 induces dose-dependent protection against challenge with virulent B. pertussis in low-dose and in high-dose intranasal mouse lung colonization models. In addition, we observed BPZE1 dose-dependent antibody titers to B. pertussis antigens, as well as cell-mediated immunity, evidenced by the amounts of gamma interferon (IFN-gamma) released from spleen cells upon stimulation with B. pertussis antigens. These two parameters may perhaps be used as readouts in clinical trials in humans that are currently being planned.

Seasonal patterns in time series of pertussis

To gain insight into pertussis disease dynamics, we studied age-specific long-term periodicity and seasonality of pertussis in The Netherlands. Hierarchical time-series models were used to analyse the monthly reported pertussis incidence in January 1996-June 2006 by age group. The incidence of pertussis showed a slightly increasing long-term trend with highest incidence rates seen in 1996, 1999, 2001 and 2004. For all age groups the annual peak incidence was found in August, except for the 13-18 years age group where the peak occurred in November. Monthly trends in adults showed high correlation with trends in age groups 0-4 years (0.94) and 5-12 years (0.92). We found no evidence for a relationship between annual rises in pertussis and the opening of schools. Concurrent annual fluctuations of pertussis incidence in adults and infants suggest frequent transmission within and between these age groups. Studying trends offers insight into transmission dynamics and may facilitate decisions on future vaccination strategies.

Poor immune responses to a birth dose of diphtheria, tetanus, and acellular pertussis vaccine

OBJECTIVES

To evaluate the safety and immunogenicity of an additional birth dose of diphtheria, tetanus, and acellular pertussis vaccine (DTaP).

STUDY DESIGN

Fifty infants between 2 to 14 days of age were randomly assigned to receive either DTaP and hepatitis B vaccines (experimental) or hepatitis B alone (control) at birth. At 2, 4, 6, and 17 months of age, DTaP and routine vaccines were administered to both groups. Safety data were collected after each dose, and sera were obtained at birth, 6, 7, 17, and 18 months. Immune responses to pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae were measured by enzyme-linked immunosorbent assay; responses to other vaccines were assessed.

RESULTS

No differences were seen between the 2 groups in either local or systemic reactions; all vaccines were well tolerated. Compared with the control group, infants in the experimental group demonstrated significantly lower geometric mean antibody concentrations for pertussis toxin and pertactin 6, 7, and 18 months, for fimbrae at 6, 7, 17, and 18 months, and for FHA at 18 months, and lower geometric mean antibody concentrations for diphtheria at 7 months. Immune responses to all other vaccine antigens were comparable.

CONCLUSION

Administration of an additional dose of DTaP at birth was safe but was associated with a significantly lower response to diphtheria and 3 of 4 pertussis antigens compared with controls.

Pertussis: review of epidemiology, diagnosis, management and prevention

Bordetella pertussis--the cause of pertussis or whooping cough--is an exclusively human pathogen. Disease elimination by vaccination should, therefore, be possible, but has proved elusive. Many industrialised countries with long established immunisation programs are currently seeing a resurgence of pertussis, despite universal vaccination with high uptake, with the highest burden in the least immunised age groups (infants under 6 months of age and persons over 10 years old). However, low recognition and reporting and insensitive diagnostic tests mean that the true burden of pertussis is still underestimated. Recently, efforts to improve diagnostic yield include the expanded use of polymerase chain reaction and serological tests but both have significant limitations. The range of antibiotics available for treatment and prophylaxis has expanded to include the newer macrolides, azithromycin and clarithromycin, and a range of universal and targeted vaccination strategies have been implemented or proposed. This paper reviews the current epidemiology of pertussis in developed countries, including modes of clinical presentation, diagnosis, management and potential vaccination strategies.

Neonatal vaccination with an acellular pertussis vaccine accelerates the acquisition of pertussis antibodies in infants

OBJECTIVES

Because young infants are at highest risk of pertussis complications, this study assessed whether neonatal acellular pertussis (aP) vaccination could provide earlier immunity.

STUDY DESIGN

Neonates (n = 121) were randomly assigned (1:1) to receive either aP or hepatitis B vaccine (HBV) (controls) vaccine at birth, followed by vaccination with DTaP-HBV-IPV/Hib at 2, 4 and 6 months. Immune responses were measured. Reactogenicity was assessed for 7 days after each dose.

RESULTS

The aP birth dose was followed by few adverse events. Reactogenicity of subsequent vaccine doses did not differ between groups. Seven serious adverse events were reported from each group; none were related to the study vaccines. At 3 months of age, vaccination with aP at birth had induced significantly higher antibody responses to the 3 pertussis antigens compared with controls. At 7 months, geometric mean/concentrations of antibodies against pertussis antigens were similar in both groups, and all subjects had reached "seroprotective" antibody concentrations against diphtheria, tetanus, and poliovirus types 1, 2, and 3. Geometric mean/concentrations of antibodies to haemophilus influenzae type b (Hib) and HBV were significantly lower in the aP group.

CONCLUSIONS

Early neonatal immunization with aP was safe, well tolerated, and resulted in earlier antibody responses, seen after the first dose of a DTaP combination vaccine. Birth dose of aP did not induce immunologic tolerance to pertussis antigens but appear to dampen responses to Hib and HBV vaccines.

Pertussis in infants: preventing deaths and hospitalisations in the very young

Pertussis is a particular concern in infants under 6 months of age. They have the highest rates and severity of disease resulting in hospitalisation or death but are too young to be protected by current vaccination schedules. We outline the current epidemiology of pertussis in Australia and four potential strategies to prevent pertussis in the very young. First, universal adult and or adolescent vaccination; second, indirect protection of infants by immunisation of parents and possibly others in close contact with the newborn, such as grandparents and health-care workers; third, newborn and early infant vaccination (from birth to 1 month of age) and fourth maternal vaccination.

Impact of acellular pertussis preschool booster vaccination on disease burden of pertussis in The Netherlands

BACKGROUND

An acellular preschool booster vaccination against pertussis has been included in the National Immunization Programme in The Netherlands, since November 2001. We studied the impact of this preschool booster on the epidemiology of pertussis.

METHODS

We analyzed and compared pertussis cases registered in the national notification system, hospital registry, and death registry between the periods 1998-2001 (without preschool booster) and 2002-2005 (with preschool booster).

RESULTS

In 2002-2005, the incidence of hospitalizations and notifications in 1-4 year olds were 48% and 44%, lower respectively, than in 1998-2001. Similarly, in 5-9 year olds the incidence of hospitalizations and notifications had decreased 32% and 15%, respectively. In 2005, vaccine effectiveness for preschool booster among children born between January 1, 1998 and January 1, 2001--all of whom had been eligible for the booster--was estimated at 79% (95% CI: 71-85). In infants aged 0-6 months, the incidence of hospitalizations per 100,000 population decreased 40%, from 222.5 to 133.6. In contrast, among cohorts aged 10-19, 20-59, and >60 years, the incidence of notifications increased 60%, 44%, and 68%, respectively.

CONCLUSIONS

The preschool booster strongly decreased the disease burden in the targeted cohorts. Importantly, the incidence in infants 0-6 months also showed a decline after introduction of the preschool booster, suggesting reduced transmission from siblings to young infants. Meanwhile, the number of pertussis cases in adolescents and adults increased. With prevention of severe pertussis among infants as focus, this effect should not be ignored in the discussion on future vaccination strategies for pertussis.

Re-emergence of pertussis in Slovenia: time to change immunization policy

The introduction of childhood vaccination has dramatically reduced morbidity and mortality of pertussis in Slovenia. However, despite high vaccination coverage for many decades, reported incidence has increased recently, to the highest incidence of 27.5/100,000 in 2006, a 6.5-times increase in comparison to the previous year. Marked shift in age distribution among reported cases was observed in recent years. In 2006, reported age-specific incidence was relatively high in children 8-12 years old, the highest among 9 years old. Similar to other countries, where children are given pre-school boosters, we also have to consider the revision of the national vaccination policy. A booster dose at school entrance or latest at 8 years of age should be introduced to decrease the transmission of disease among school children and to further reduce the burden of disease among infants.

What is new in pertussis?

Despite high vaccination coverage, over the last fifteen years there has been a worldwide resurgence of B. pertussis infection. While classical pertussis in the prevaccine era was primarily a childhood disease, today with widespread vaccination, there has been a shift in the incidence of disease to adolescents and adults. Centers of Disease Control and Prevention (CDC) data from 2004 reveal a nearly 19-fold increase in the number of cases in individuals 10-19 years and a 16-fold increase in persons over 20 years. Indeed adolescent and adults play a significant role in the transmission of pertussis to neonates and infants who are vulnerable to substantial morbidity and mortality from pertussis infection. Several explanations have been proposed to explain the increasing incidence of disease, with waning immunity after natural infection or immunization being widely cited as a significant factor. Improving molecular biology diagnostic techniques, namely PCR assays, also accounts for the increasing laboratory diagnosis of pertussis. Expanding vaccination strategies including universal immunization of adolescents, targeted immunization of adults, and in particular, healthcare workers, childcare providers and parents of newborns, will likely improve pertussis control. With pertussis continuing to pose a serious threat to infants, and greatly affecting adolescents and adults, there remains a need to: (a) increase the awareness of physicians as to the growing pertussis problem, (b) standardize diagnostic techniques, and (c) implement various new vaccine strategies to enhance its control.

Clinical outcome of pertussis in Sweden: association with pulsed-field gel electrophoresis profiles and serotype

In Sweden, acellular pertussis vaccines were introduced at 3, 5 and 12 months of age in 1996, after a 17-year hiatus without pertussis vaccination. An intensified surveillance of pertussis was initiated in October 1997, including collection of clinical data as well as Bordetella pertussis isolates in culture or PCR-confirmed cases of pertussis among children born from January 1996 to September 2004. We analysed the association of pulsed-field gel electrophoresis (PFGE) profile and serotype with severity of disease for all children followed during the first 7 years of the project. There were in all 927 children for whom both clinical information and strain characterisation data were available. 260 of these children were hospitalised during the pertussis episode. When duration of hospital stay was compared between children with different groups of strains, characterised by PFGE profile or serotype, there was a significantly higher proportion of children with long duration of hospital stay in the most frequent PFGE profile group (BpSR11) compared to the PFGE group of all other profiles (p=0.041). There was no statistically significant association between serotype and hospitalisation rate or duration of hospital stay, neither was there any statistically significant association between serotype or PFGE profile and duration of spasmodic cough or presence of complications.

Pertussis in Argentina and France

We have studied the epidemiology of pertussis in two countries, Argentina and France, which have similar histories of long-term mass vaccination with a whole-cell vaccine. Both countries display a comparable epidemiology, with an increase of the incidence of the disease in non-vaccinated newborns. We used pulsed-field gel electrophoresis (PFGE) analysis and genotyping to compare Bordetella pertussis clinical isolates recovered in Argentina and France in 2001-2004. The majority of the isolates harbors prn2 allele and belongs to PFGE IVbeta group. Isolates were found to be very similar genetically suggesting a common evolution of the disease in these two countries using the same vaccine.

Pertussis: severe clinical presentation in pediatric intensive care and its relation to outcome

OBJECTIVE

To describe our institutional experience in the management of infants and children with pertussis admitted during a 20-yr period (January 1985 through December 2004) and also to study the relation between method of presentation and outcome.

SETTING

Pediatric intensive care unit in a university-affiliated tertiary pediatric hospital in Melbourne, Australia.

DESIGN/METHODS

Retrospective review of medical records and radiology reports of patients with a diagnosis of pertussis identified from the pediatric intensive care unit database.

RESULTS

A total of 49 patients (median age, 6 wks; interquartile range, 4-8 wks) required 55 admission episodes to the pediatric intensive care unit. Main reasons for admission were apnea with or without cough paroxysms (63%), pneumonia (18%), and seizures (10%). None of the infants had completed the primary course of immunization, and 94% had not received a single dose of pertussis vaccine. Infants presenting with pneumonia presented earlier (p = .001), had longer intensive care stay (p = .007), higher white cell count (p < or = .001), lower Pao2 at admission (p = .020), and higher mortality. Six infants out of seven needing circulatory support died (including all four treated with extracorporeal membrane oxygenation), and all deaths (n = 7) occurred in infants who had pneumonia at presentation.

CONCLUSION

Patients with pertussis, presenting as apnea (with or without cough paroxysms), treated in the pediatric intensive care unit had 100% survival. However, pneumonia as the main reason for admission and the need for circulatory support is associated with a very poor outcome. A deeper understanding of the molecular basis of Bordetella pertussis and its relation to the human host might offer means for future therapies.

Pertussis resurgence: diagnosis, treatment, prevention, and beyond

The introduction of routine vaccination against Bordetella pertussis more than a half century ago led to a drastic decline in the number of reported cases of pertussis. It was originally believed that lifelong immunity was afforded after vaccination. Unfortunately, this belief is flawed, as the highest number of pertussis cases since 1959 was reported in 2004. This significant increase has led to additional research on immunity, vaccination, and treatment of B. pertussis in all age groups. We performed a MEDLINE search of literature from 1966-2006 to evaluate and review the existing data on immunity to and prevention or treatment of B. pertussis infections. Additional articles were identified from the bibliographies of reviewed literature. Numerous articles pertaining to these topics have been published recently. The most significant changes in the management of this infectious disease surround the new recommendations by the Advisory Committee on Immunization Practices for adult and adolescent immunizations to assist in preventing outbreaks of B. pertussis. The Centers for Disease Control and Prevention recently published guidelines updating the recommended pharmacologic agents for treatment or prevention of B. pertussis. Despite decades of successful vaccination programs, pertussis continues to be a problematic disease. Fortunately, data and vaccines are now available that make development of a pertussis booster vaccination campaign reasonable. However, until widespread compliance with such programs is achieved, clinicians need to maintain vigilance against pertussis.