Prevention of pertussis: Recommendations derived from the second Global Pertussis Initiative roundtable meeting

Country-Specific Data and Priorities for Pertussis in Latin America: Recent Findings From the Global Pertussis Initiative

In 2023, the Global Pertussis Initiative met to assess the burden of and vaccination policies against pertussis in 10 Latin American countries. Although pertussis is a notifiable disease in the represented countries, poor disease awareness, underrecognition in older individuals, and limited laboratory capacity and supplies challenge the collection of robust epidemiological data. Infants in all 10 countries receive a 3-dose primary series followed by ≥2 boosters. Except for Paraguay and Venezuela, governments of the represented countries advise or mandate vaccination in pregnancy; however, coverage rates remain suboptimal. Healthcare providers and the public should be educated on how mothers and other contacts can serve as asymptomatic carriers of Bordetella pertussis (transmitting disease to vulnerable infants) and of the potentially unique presentation of pertussis in adolescents and adults. The burden of pertussis in Latin America can be reduced by improving vaccination coverage of the primary series, increasing vaccination in pregnancy, and instituting universal vaccination of adults.

Pertussis vaccination campaign among health care workers and validity of recall of previous adverse events following immunization

BACKGROUND

To minimize Bordetella pertussis transmission, health care workers (HCW) should be regularly vaccinated against pertussis, e.g. every 10 years. Therefore, the previous 2012/2013 vaccination campaign in our hospital was repeated in 2023. Here we describe our findings of the campaign and a nested study on the reliability of recall of adverse events (AE) after 10 years.

METHODS

This was a prospective observational study including all HCW with patient contact. Those who had their last pertussis vaccination ≥10 years ago or with unknown date were offered a booster dose of Tdap (Adacel®) or Tdap-IPV (Adacel-Polio®) vaccine and were asked to report reactogenicity for seven days following vaccination. Those HCW who had participated in the 2012/2013 campaign were asked to report recall of vaccine tolerability back then.

RESULTS

Of 916 eligible HCW, 705 (77.0 %) responded and 191 (27.1 %) of them were not up to date. Of these, 150 (78.5 %) plus 6 who were still up-to-date were vaccinated (Tdap-IPV: N = 91, 58.3 %, Tdap: N = 65; 41.7 %). After the vaccination campaign 684 (74.7 %) of all eligible HCW were up to date with their pertussis immunization status, including 63.4 % of nurses and 76.9 % of physicians. The most common adverse events in 133 (88.1 %) HCW were pain (66.7 %, day two), swelling (27.3 %, day two) and exhaustion (21.5 %, day two). Of 52 HCW who were vaccinated in both campaigns, 13 had ≥ 1 documented AE back in 2012/2013, of which only one remembered that the vaccination had not been well tolerated back then (Cohen's Kappa -0.04 for AE, -0.11 for swelling, -0.03 for redness and 0 for fever).

CONCLUSION

We achieved an up-to date pertussis vaccination status in the majority of HCW. However, vaccinating all eligible HCW remains challenging in the absence of mandatory immunization. The recall of previous AE following immunization was poor.

Pertussis in Southeast Asia: country-level burden and recommendations from the Global Pertussis Initiative

The Global Pertussis Initiative met in March 2024 to discuss the burden of pertussis and prevention efforts in six Southeast Asian countries: Cambodia, Indonesia, Malaysia, Singapore, Thailand, and Vietnam. Except for Cambodia, pertussis is a notifiable disease; data accuracy varies within and between countries. Most cases in the region are diagnosed based on clinical suspicion. Whole-cell and acellular pertussis combination vaccines are available, but the composition differs between countries. Immunization against pertussis is well-established, but policies regarding boosting vary. Vaccination in pregnancy represents a still-neglected opportunity to protect infants. The Global Pertussis Initiative recommends enacting vaccination in pregnancy in countries without and increasing coverage in countries with policies already in place. There is a need to correct the misperception that pertussis affects children exclusively and that childhood vaccines provide lifelong protection. Education is key to widespread understanding of the threat of pertussis and removing barriers to vaccination in Southeast Asia.

Pertussis Vaccination for Adults: An Updated Guide for Clinicians

Pertussis, or whooping cough, is a highly contagious respiratory infection caused by the Gram-negative bacterium Bordetella pertussis. Although traditionally associated with children, pertussis is increasingly prevalent among adults, particularly those with comorbidities or weakened immune systems, where it can lead to severe complications. Diagnosing pertussis in adults can be challenging due to its nonspecific symptoms, underreporting, and the limited sensitivity of available diagnostic tests. While treatment with macrolides is generally effective, it may not significantly alter the clinical course of the disease, and growing concerns about macrolide resistance are emerging. Vaccination remains the cornerstone of prevention, offering proven immunogenicity, efficacy, and safety. However, vaccination uptake remains low, partly due to limited patient awareness and insufficient prioritization by healthcare professionals. This review aims to provide clinicians with critical insights into pertussis epidemiology, vaccination strategies, and the latest guideline recommendations, empowering them to engage in meaningful discussions with adult patients and advocate for increased vaccination to combat this often-overlooked infection.

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.

Strategies to increase uptake of maternal pertussis vaccination

INTRODUCTION

Pertussis is a highly contagious respiratory disease that results in disproportionate morbidity and mortality in infants who have yet to receive the primary diphtheria-tetanus-pertussis vaccine series. In the preceding decades numerous countries began to pursue either prenatal vaccination of pregnant women or postpartum vaccination of caregivers to protect infants. Despite proven benefit, maternal uptake of pertussis vaccine continues to remain suboptimal.

AREAS COVERED

Many studies have been conducted to address the suboptimal uptake of maternal pertussis vaccination. This systematic review was undertaken to systematically identify those studies, highlight the most successful strategies and find the knowledge gaps that need to be filled over the coming years to improve vaccine uptake. Twenty-five studies were identified from six different databases.

EXPERT OPINION

Five different interventions were shown to be successful in promoting uptake of pertussis vaccination: (1) standing orders, (2) opt-in orders, (3) provider education, (4) on-site vaccination and (5) interactive patient education. Three major knowledge gaps were also identified that need to be filled over the coming years: (1) lack of studies in low- and middle-income countries, (2) lack of studies targeting midwives and/or home birth and (3) lack of studies on the process of vaccine communication.

[A comparative analysis of the Chinese and English descriptions of typical pertussis manifestations and recommendations for the diagnosis of pertussis-like or pertussis syndrome]

The Chinese and English names of pertussis or whooping cough show the important clinical features of the disease in terms of its course and cough characteristics respectively. In the clinical description of typical pertussis, the meanings of the Chinese and English words are not completely consistent, such as spastic cough versus paroxysmal cough, spasmodic stage/phase versus paroxysmal stage/phase, and "back-hook" versus whoop, and some descriptions in English are not seen in Chinese. This article aims to provide more comprehensive information for the understanding of pertussis by comparing the descriptions of typical clinical manifestations of pertussis in Chinese and English literatures and to put forward suggestions for the diagnosis of pertussis syndrome based on typical clinical manifestations.

Therapeutic effect of vitamin K1 combined with meropenem on the treatment of pertussis syndrome

Clinical efficacy of vitamin K1 combined with meropenem on the treatment of pertussis syndrome was evaluated. Clinical data of 170 children with pertussis syndrome treated in the Second People's Hospital of Liaocheng from March 2015 to March 2017 were collected. Of these, 87 patients who were treated with vitamin K1 combined with meropenem were regarded as the experiment group. A total of 83 patients who were treated with meropenem alone were regarded as the control group. Both groups were treated with anti-infective, respiratory support, antispasmodic, expectorant and other basic treatments. The therapeutic effects, duration of spasmodic cough, length of hospitalization, antipyretic time, duration of voice disappearance and healing time were observed between the two groups. The duration of spasmodic cough and length of hospitalization in the experiment were lower than the control group, and the difference was statistically significant between the groups (P<0.05). The explicit efficiency (51.72%) and total effective efficiency (99.55%) in the experiment group were significantly higher than the explicit efficiency (36.14%) and total effective efficiency (78.31%) in the control group. There was a statistically significant difference between the groups (P<0.05). The voice disappearance time and healing time in the experiment group were significantly shorter than the control group, and there was a statistically significant difference between the groups (P<0.05). The antipyretic time in the experiment group was lower than that of the control group, the difference between the groups was not statistically significant (P>0.05). The treatment with vitamin K1 and meropenem has a significant effect in relieving pediatric pertussis syndrome, it can shorten the duration of spasmodic cough, antipyretic time, duration of voice disappearance and length of hospitalization in children with pertussis syndrome, and improve the efficacy clinically.

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.

Recommendations to control pertussis prioritized relative to economies: A Global Pertussis Initiative update

Pertussis is a vaccine-preventable disease that causes morbidity and mortality, particularly in infants and children <5 years of age. The Global Pertussis Initiative (GPI) recommendations represent a systematic evaluation and prioritization of strategies to prevent pertussis-related infant and child deaths, reduce global disease burden and prevent resurgence through vaccination strategies and public health policies at national, regional and local levels. The GPI recommendations are based on clinical trials and observational and surveillance data, which are essential in the planning, implementation and evaluation of vaccination practices and best use of available resources. Many low- and middle-income countries (LMIC) continue to use whole-cell pertussis (wP) vaccines for primary vaccination, while most high-income countries have replaced wP with the less-reactogenic acellular pertussis (aP) vaccines. This present manuscript pertains to discussions held during the GPI's meeting on November 11-13, 2016, in Cape Town, Republic of South Africa. The GPI recommends that LMIC aim for high coverage of infant series pertussis vaccines as a priority. In LMIC and countries with constrained vaccine funding, if wP vaccines are currently used, wP should continue to be used. Furthermore, given that protection against disease and death due to pertussis in neonates is a key priority of the GPI, it recommends that ap immunization in pregnancy should be implemented as a priority in all countries if resources allow. Given that surveillance and epidemiology data on which to base vaccine decisions are important, the GPI also suggests that, in areas where wP vaccines are implemented, standardization and calibration of wP vaccines are checked, considering the many different manufacturers and variable standards of production and quality control. In addition, as immunity to pertussis wanes following the primary infant series of vaccination, the GPI further recommends that toddlers, adolescents, healthcare and childcare workers receive booster vaccine doses, where resources allow.

Adult Caregiver Influenza Vaccination Through Administration in Pediatric Outpatient Clinics: A Cocooning Healthcare Improvement Project

BACKGROUND

Pediatric exposure to influenza-infected adult caregivers (AC) is a significant risk factor for developing influenza. Poor access to vaccines contributes to low adult vaccination rates. We offered adult vaccination at regularly scheduled pediatric office visits and examined barriers to improve future vaccination rates.

METHODS

Via a retrospective chart review, we identified ACs who received an influenza vaccination at 1 of 3 pediatric clinics within an academic center from August 2015 to May 2016. We screened for demographics of ACs and their children. Rates of AC vaccination and AC refusal were not measured.

RESULTS

A total of 297 ACs representing 518 children received their influenza vaccine at their child's pediatric office. The mean age of ACs was 35.9 years (range, 22-70 years) and 68.5% were mothers. Most ACs (n = 294, 99%) receiving the vaccine had private insurance. Almost all ACs received their vaccination on the day of the child's visit (n = 250, 84%). A total of 49.6% of AC's children had high-risk illnesses. Parents of children with Medicaid were under-represented because of high parental copays (n = 3, 1%). The highest clinic vaccine participation was noted at the clinics with lowest Medicaid populations.

CONCLUSIONS

ACs readily accepted influenza vaccination at their child's pediatric primary care office. Increased vaccination acceptance occurred when ACs were female, had private insurance, if their child had a chronic illness and if the vaccination was offered the same day as their child's appointment. Likely reason for low acceptance in ACs with Medicaid insurance is high cost; thus, staff, well-aware of Medicaid's nonreimbursement, likely offered the vaccine less to these parents.

Prospective multinational serosurveillance study of Bordetella pertussis infection among 10- to 18-year-old Asian children and adolescents

OBJECTIVES

Bordetella pertussis continues to cause outbreaks worldwide. To assess the role of children and adolescent in transmission of pertussis in Asia, we performed a multinational serosurveillance study.

METHODS

From July 2013 to June 2016, individuals aged 10 to 18 years who had not received any pertussis-containing vaccine within the prior year were recruited in 10 centres in Asia. Serum anti-pertussis toxin (PT) IgG was measured by ELISA. Demographic data and medical histories were obtained. In the absence of pertussis immunization, anti-PT IgG ≥62.5 IU/mL was interpreted as B. pertussis infection within 12 months prior, among them levels ≥125 IU/mL were further identified as infection within 6 months.

RESULTS

A total of 1802 individuals were enrolled. Anti-PT IgG geometric mean concentration was 4.5, and 87 (4.8%) individuals had levels ≥62.5 IU/mL; among them, 73 (83.9%) had received three or more doses of pertussis vaccine before age 6 years. Of 30 participants with persistent cough during the past 6 months, one (3.3%) had level ≥125 IU/mL. There was no significant difference in proportions with anti-PT IgG ≥62.5 IU/mL among age groups (13-15 vs. 10-12 years, 16-18 vs. 10-12 years), between types of diphtheria, pertussis and tetanus (DTP; whole cell vs. acellular), number of doses before age 6 years within the DTP whole-cell pertussis vaccine (five vs. four doses) or acellular pertussis vaccine (five vs. four doses) and history of persistent cough during the past 6 months (yes vs. no).

CONCLUSIONS

There is significant circulation of B. pertussis amongst Asian children and adolescents, with one in 20 having serologic evidence of recent infection regardless of vaccination background.

Pertussis epidemiology in Argentina: TRENDS after the introduction of maternal immunisation

Data on the impact of the recently recommended maternal pertussis vaccination are promising, but still insufficient to universalise this approach. We thus compared the epidemiological data prior to the implementation of this vaccination strategy in Argentina (2012) with the figures reported after 2012. During that 2010–2016 period, two outbreaks occurred, one in 2011 and another in 2016. In the former, the incidence was 6.9/100 000 inhabitants and the case-fatality rate 2.6%. Thereafter, a decline in incidence was detected until 2014. During 2015 and 2016 an increase in the incidence transpired, but this rise was fortunately not accompanied by one in the case fatality ratio. Indeed, in 2016 the case fatality ratio was the lowest (0.6%). Moreover, during the 2016 outbreak, the incidence (3.9/100 000 inhabitants) and the case severity detected in the most vulnerable population (infants 0–2 months) were both lower than those in 2011. Consistent with this pattern, in 2016, in the most populated province of Argentina (Buenos Aires), the case percentage with laboratory-positive results indicating a high number of symptoms (59.1% of the total cases) diminished compared with that detected in the 2011 outbreak without maternal immunisation (71.9%). Using the mathematical model of pertussis transmission we previously designed, we assessed the effect of vaccination during pregnancy on infant incidence. From comparisons between the epidemiological data made through calculations, emerged the possibility that vaccinating women during pregnancy would benefit the infants beyond age 2 months, specifically in the 2–12-month cohort.

Will we have new pertussis vaccines?

Despite wide vaccination coverage with efficacious vaccines, pertussis is still not under control in any country. Two types of vaccines are available for the primary vaccination series, diphtheria/tetanus/whole-cell pertussis and diphtheria/tetanus/acellular pertussis vaccines, in addition to reduced antigen content vaccines recommended for booster vaccination. Using these vaccines, several strategies are being explored to counter the current pertussis problems, including repeated vaccination, cocoon vaccination and maternal immunization. With the exception of the latter, none have proven their effectiveness, and even maternal vaccination is not expected to ultimately control pertussis. Therefore, new pertussis vaccines are needed, and several candidates are in early pre-clinical development. They include whole-cell vaccines with low endotoxin content, outer membrane vesicles, new formulations, acellular vaccines with new adjuvants or additional antigens and live attenuated vaccines. The most advanced is the live attenuated nasal vaccine BPZE1. It provides strong protection in mice and non-human primates, is safe, even in immune compromised animals, and genetically stable after in vitro and in vivo passages. It also has interesting immunoregulatory properties without being immunosuppressive. It has successfully completed a first-in-man clinical trial, where it was found to be safe, able to transiently colonize the human respiratory tract and to induce immune responses in the colonized subjects. It is now undergoing further clinical development. As it is designed to reduce carriage and transmission of Bordetella pertussis, it may hopefully contribute to the ultimate control of pertussis.

Decreased incidence of pertussis in young adults after the introduction of booster vaccine in military conscripts: Epidemiological analyses of pertussis in Finland, 1995-2015

INTRODUCTION

In 2005, in Finland, the whole-cell pertussis vaccine was replaced by acellular given at 3-5-12months, and boosters at 4 and 11-15years of age. From July 2012, military conscripts have been offered a pertussis booster dose. Conscription is mandatory for Finnish men, and >95% were 19-21years old when enrolled during 2012-2015. We describe the epidemiology of pertussis in Finland during 1995-2015, and show the indirect effect of the booster in conscripts on pertussis incidence in the Finnish population.

MATERIALS AND METHODS

We extracted data on laboratory confirmed notified pertussis cases from the National Infectious Diseases Register. We calculated annual incidence using as denominator population data and incidence rate ratios (IRR) using Poisson regression.

RESULTS

The overall pertussis incidence peaked in 2004 (31/100,000) and was lowest in 2015 (3.0/100,000), with 66 reported cases in <3months infants in 2004 versus 6 in 2015. The majority of the cases were female (59%) with a male-to-female case ratio of 1:1.5. Cases were spread throughout the year with highest incidence during August-February. Among the 19- to 21-year-olds in the general population, incidence decreased from 49/100,000 in 2011 to 0.51/100,000 in 2015 (IRR=0.01; 95%CI, 0.00-0.16). Among the same age group, comparing the 3.5-year period before and after July 2012, incidence decreased from 33/100,000 to 5.3/100,000 (IRR=0.16; 95%CI, 0.06-0.40) in males and from 16/100,000 to 5.0/100,000 (IRR=0.31; 95%CI, 0.11-0.84) in females.

CONCLUSIONS

Implementation of the pertussis booster dose in Finnish military conscripts was followed by a significant decrease in pertussis incidence both among the 19- to 21-year-old males and females, possibly reflecting herd immunity effect. Together with booster doses in adolescents this has resulted in low incidence in the whole population including infants. Our results support the implementation of the booster dose for conscripts. We recommend continuing monitoring pertussis epidemiology to optimize pertussis vaccination strategies in Finland.

[Pertussis diagnosis: the limitation of the currently used criteria and the suggestion of Global Pertussis Initiative]

It has been recognized that pertussis is a disease that affects all age groups. There are obvious limitations in the currently used diagnostic criteria with "one-size-fits-all" definition, which is not advantageous to start individual treatment and perform strategies for preventing the transmission. Therefore, the expert group of Global Pertussis Initiative gives a suggestion for the diagnosis of pertussis. Based on the related published studies, the present article analyzes the limitations of the current criteria, and introduces the GPI's suggestion in detail.

Pertussis vaccination in pregnancy

Pertussis has had a resurgence with the highest incidence and complication rates in young infants, and deaths occurring mainly at < age 3 months. Infants are infected by older individuals whose immunity has waned. Strategies such as targeted immunization of infant caregivers have had limited success. Pertussis vaccination in pregnancy may protect infants through passive and active transfer of maternal antibodies that protect the infant until the primary immunization series. Studies show vaccinating pregnant women with acellular pertussis vaccine is safe for mother and infant, immunogenic with efficient transfer of antibodies to infants, and effective in preventing pertussis in young infants. Vaccine uptake in pregnant women is sub-optimal, but provider recommendation is the most important factor in improving vaccination rates. Studies are ongoing to determine the best timing of vaccination to protect infants, and into other strategies. Vaccinating pregnant women offers hope to prevent pertussis-related morbidity and mortality in infants worldwide.

A Bordetella pertussis proteoliposome induces protection in mice without affecting the immunogenicity of diphtheria and tetanus toxoids in a trivalent formulation

In this study, a formulation of Bordetella pertussis proteoliposome (PLBp), diphtheria, and tetanus toxoids and alum (DT-PLBp) was evaluated as a trivalent vaccine candidate in BALB/c mice. Vaccine-induced protection was estimated using the intranasal challenge for pertussis and enzyme-linked immunosorbent assay fvto assess serological responses for diphtheria or tetanus. Both, diphtheria-tetanus-whole cell pertussis (DTP) and diphtheria-tetanus vaccines (DT) were used as controls. Animals immunized with DT-PLBp, PLBp alone, and DTP showed total reduction of CFU in lungs 7 days after intranasal challenge. Likewise, formulations DT-PLBp, DTP, and DT elicited antibody levels ≥2 IU/mL against tetanus and diphtheria, considered protective when neutralization tests are used. Overall, results showed that combination of PLBp with tetanus and diphtheria toxoids did not affect the immunogenicity of each antigen alone.

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.

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.

Under-recognized pertussis in adults from Asian countries: a cross-sectional seroprevalence study in Malaysia, Taiwan and Thailand

Surveillance data on the burden of pertussis in Asian adults are limited. This cross-sectional study evaluated the prevalence of serologically confirmed pertussis in adults with prolonged cough in Malaysia, Taiwan and Thailand. Adults (⩾19 years) with cough lasting for ⩾14 days without other known underlying cause were enrolled from outpatient clinics of seven public and/or private hospitals. Single blood samples for anti-pertussis toxin antibodies (anti-PT IgG) were analysed and economic impact and health-related quality of life (EQ-5D) questionnaires assessed. Sixteen (5·13%) of the 312 chronically coughing adults had serological evidence of pertussis infection within the previous 12 months (anti-PT IgG titre ⩾62·5 IU/ml). Three of them were teachers. Longer duration of cough, paroxysms (75% seroconfirmed, 48% non-seroconfirmed) and breathlessness/chest pain (63% seroconfirmed, 36% non-seroconfirmed) were associated with pertussis (P < 0·04). Of the seroconfirmed patients, the median total direct medical cost per pertussis episode in public hospitals (including physician consultations and/or emergency room visits) was US$13 in Malaysia, US$83 in Taiwan (n = 1) and US$26 in Thailand. The overall median EQ-5D index score of cases was 0·72 (range 0·42–1·00). Pertussis should be considered in the aetiology of adults with a prolonged or paroxysmal cough, and vaccination programmes considered.

The impact of parental postpartum pertussis vaccination on infection in infants: A population-based study of cocooning in Western Australia

During a pertussis epidemic in 2011-2012 the Western Australian (WA) Department of Health implemented a 'cocooning' programme, offering free pertussis-containing vaccine (dTpa) to new parents. We assessed the impact of vaccinating parents with dTpa on the incidence of pertussis infection in newborns. Births in WA during 2011-2012 were linked to a register of parental pertussis vaccinations and to notified reports of laboratory-proven pertussis in children <6 months of age. Parents who received dTpa during the four weeks after their child's birth were defined as 'vaccinated postpartum.' Cox proportional-hazards methods were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the risk of pertussis infection among infants born to parents vaccinated postpartum vs. unvaccinated parents, adjusted for maternal age, geographic region, timing of birth, and number of siblings. Of 64,364 live-births, 43,480 (68%) infants had at least one vaccinated parent (60% of mothers and 36% of fathers). After excluding records where parent(s) were either vaccinated prior to the birth, vaccinated >28 days after the birth, the vaccination date was uncertain, or the child died at birth (n=42), the final cohort contained 53,149 children, 118 of whom developed pertussis. There was no difference in the incidence of pertussis among infants whose parents were both vaccinated postpartum compared to those with unvaccinated parents (1.9 vs 2.2 infections per 1000 infants; adjusted HR 0.91; 95%CI 0.55-1.53). Similarly, when assessed independently, maternal postpartum vaccination was not protective (adjusted HR 1.19; 95%CI 0.82-1.72). Supplemental sensitivity analyses which varied the time period for parental vaccination and accounted for under-reporting of vaccination status did not significantly alter these findings. In our setting, vaccinating parents with dTpa during the four weeks following delivery did not reduce pertussis diagnoses in infants. WA now provides dTpa vaccine to pregnant women during the third trimester.

[Is it ethically acceptable to invite a pregnant woman to enroll in a clinical trial with Tdap if it could entail not being vaccinated with Tdap before delivery?]

Pertussis incidence has increased in recent years, especially among infants aged <2months. A number of Spanish regions have started a vaccination program with Tdap vaccine to all pregnant women in the third trimester of pregnancy. An observational study has shown that this strategy reduces the number of cases of pertussis by 90% in infants aged <2months. Mathematical models showed that a cocooning strategy (i.e. vaccination of the mother at immediate postpartum, and other adults and adolescents who have close contact with the newborn and caregivers) will reduce the incidence of pertussis by 70% in infants aged <2months. It is intended to conduct a clinical trial in which 340 pregnant women will receive Tdap vaccine, whereas another 340 pregnant woman will be vaccinated soon after delivery. Vaccination with Tdap will be offered to all partners and caregivers of the newborn. After assessing both the ethical and scientific reasons supporting the trial, it is concluded that it is ethically and legally acceptable to invite pregnant women living in communities where Tdap vaccination has been implemented to participate in the trial.

Uptake of a government-funded pertussis-containing booster vaccination program for parents of new babies in Victoria, Australia

INTRODUCTION

An epidemic of Bordetella pertussis in Victoria, Australia, led to the implementation of a Government-funded vaccination program for parents of new babies. The rationale was to protect unimmunised infants from infection by vaccinating parents with a pertussis-containing vaccine. This is known as cocooning.

AIM

To estimate uptake of the vaccine among parents of new babies, two-and-a-half years after the program was implemented.

METHODS

A state-wide cross-sectional survey of parents was conducted to ascertain vaccine uptake, and to identify where and when the vaccination took place. Surveys were administered between 15 February and 14 March 2012, inclusive.

RESULTS

Of 6308 surveys distributed, 2510 completed surveys were returned (response rate 40%). Ninety-five surveys completed outside the study period were excluded, leaving 2415 available for analysis. Overall, 1937 (80%) mothers and 1385 (70%) fathers were vaccinated in relation to the birth of their most recent child. A majority of mothers were vaccinated in hospital (62%). Most fathers were vaccinated by a general practitioner (72%). The most common point at which mothers were vaccinated was before their child turned two weeks of age (65%). Fathers' vaccination time-point varied more widely: during pregnancy (25%); before their child turned two weeks of age (29%); and when their child was between two and eight weeks of age (28%).

CONCLUSION

Results of this survey indicated excellent uptake of the vaccine among both mothers and fathers under the Government-funded cocooning program. The findings are suggestive of an effective communications program designed to raise awareness of the risks of pertussis, and to promote availability of the funded vaccination program. The results may contribute to policy implementation of adult immunisation programs such as cocooning.

Bordetella parapertussis outbreak in Bisham, Pakistan in 2009–2010: fallout of the 9/11 syndrome

Pertussis or whooping cough is a highly contagious community disease mainly caused by Bordetella pertussis and B. parapertussis. We report a minor outbreak of whooping cough (2009–2010) in symptomatic subjects from Bisham, near Swat, Khyber Pukhtoonkhawa province, Pakistan. Interestingly, our results show that all the culture-positive isolates (n = 21) collected from children (average age 3·46 years), were identified as B. parapertussis after routine identification tests and PCR IS481, IS1001 and IS1002. Furthermore, in the affected patients, none had received immunization with diphtheria-pertussis-tetanus (DTPw) vaccine. Therefore, the possibility of the re-emergence of the disease due to limitation of basic health services as a result of the political unrest due to the 9/11 situation is also examined. Moreover, we discuss the importance of vaccinating both adults and children with DTPwPaw vaccine containing both organisms for better protection.

Clinical and laboratory features of pertussis in hospitalized infants with confirmed versus probable pertussis cases

BACKGROUND

The clinical presentations of pertussis infection have considerable variation. Many infections and illnesses can cause prolonged repetitive paroxysmal cough that could be confused with Bordetella pertussis infection.

AIM

This retrospective study was designed to compare the clinico-laboratory findings between two groups of hospitalized infants with confirmed, and those who have clinical pertussis disease; to identify the possible additional diagnostic clues "for the diagnosis of confirmed pertussis disease".

SUBJECTS AND METHODS

The study population consisted of infants ≤12 months of age with clinical diagnosis of pertussis that fulfilled the World Health Organization definition for pertussis or those diagnosed by physicians. Clinico-laboratory findings were compared between two groups of patients (confirmed vs. clinical cases).

RESULTS

From a total of 118 infants admitted with a clinical diagnosis of pertussis, 16% (19/118) were confirmed by laboratory to have confirmed pertussis. Twelve of 19 (63%) and 71.99% of confirmed and clinical cases were younger than 6 months of age, respectively. For most patients, the duration of symptoms before hospitalization was <14 days. There were no significant differences between two groups of patients for paroxysmal cough and facial discoloration. However, whoop and apnea were more common among confirmed pertussis cases: P = 0.01, and P = 0.02, respectively. Leukocytosis (≥16,000/ml) (P = 0.01) and lymphocytosis (≥11,000) (P = 0.02) were reported significantly more frequently in confirmed pertussis cases.

CONCLUSION

Given the unavailability of a highly sensitive diagnostic test, in every afebrile patient with paroxysmal cough lasting for ≥7 days associated with whoop and/or apnea, particularly if accompanied by leukocytosis/lymphocytosis, pertussis disease should be considered. In this situation, prompt administration of empiric treatment for cases, and providing control measures to prevent infection transmission to contacts are recommended.

Pertussis resurgence in a highly vaccinated population, Mazandaran, North of Iran 2008-2011: an epidemiological analysis

OBJECTIVE

To describe the epidemiological characteristics of pertussis cases reported to Mazandaran Center for Diseases Control and Prevention (P-CDC) during the years 2008-2011 in Mazandaran, North of Iran.

METHODS

The patients included were those who fulfilled the WHO definition for pertussis or those clinically diagnosed by physicians. The demographic features of cases, their vaccination status, the incidence rate per 100,000 population, the relative proportion of cases for each age group, and their relation to vaccination status of the patients were all determined.

RESULTS

During the study period, a total of 518 cases of pertussis were reported; of which 43 were confirmed. The highest incidence rate and the largest proportion were 135.5 cases/100,000 and 37.7 %, respectively, observed in infants <12 mo of age. Almost 35.7 % of the cases were under vaccinated, however 54.4 % of them were fully vaccinated.

CONCLUSIONS

Pertussis infection has re-emerged in Mazandaran. It has caused a significant health problem in the susceptible young infants, and also among completely vaccinated children. Implementing strategies to protect these vulnerable infants and studies to evaluate the immunogenicity and efficacy of pertussis vaccine in Iran is recommended. It was difficult to confirm pertussis in the majority of cases, therefore, providing and improving laboratory diagnostic methods seems to be an urgent requirement.

Characteristics of pertussis outbreaks in Catalonia, Spain, 1997 to 2010

In Catalonia, pertussis outbreaks must be reported to the Department of Health. This study analyzed pertussis outbreaks between 1997 and 2010 in general and according to the characteristics of the index cases. The outbreak rate, hospitalization rate and incidence of associated cases and their 95%CI were calculated. Index cases were classified in two groups according to age (&lt;15 years and ≥15 years) and the vaccine type received: whole cell vaccine (DTwP) or acellular vaccine (DTaP). During the study period, 230 outbreaks were reported. The outbreak rate was 2.43 × 10(-6) persons-year, and outbreaks ranged from 2 to 32 cases, with a median duration of 18 days. There were 771 associated cases, with an incidence rate of 0.8 × 10(-5) persons-year.   After classifying outbreaks according to the age of the index case, 126 outbreaks (1.3 × 10(-6) persons-year) had an index case aged &lt;15 y and 87 (0.87 × 10(-6) person-year) had an index case aged ≥15 y (RR = 1.44, 95%CI 1.10-1.90; P = 0.007). Between 2003 and 2010, after the introduction of the acellular vaccine, the index case was vaccinated with DTwP vaccine in 25 outbreaks (0.43 × 10(-6) persons-year) and with DTaP vaccine in 32 outbreaks (0.55 × 10(-6) person-year) (RR = 0.78, 95%CI 0.46-1.31; P = 0.35). Of cases, 37.2% were correctly vaccinated, suggesting waning immunity of pertussis vaccine protection and endogenous circulation of pertussis. A greater number of outbreaks had an index case aged &lt;15 y. No changes in the disease incidence, associated cases and hospitalization rate were observed after the introduction of DTaP.

Tdap: The Need to Educate and Immunize

The resurgence of pertussis is puzzling, especially given the requirement that children complete recommended immunizations prior to school entry. Are adult carriers unknowingly infecting children? What do adult caregivers know about pertussis and the tetanus, diphtheria, and acellular pertussis (Tdap) booster vaccine? How can the incidence of pertussis in children younger than 2 years, a group most at risk for complications of the disease, be reduced? This article examines the incidence of pertussis and strategies to reduce pertussis incidence in the United States. If the need for Tdap vaccine is identified and favorably received by adults, immunization programs can be arranged at worksites to better protect infants who are most at risk for pertussis.

When is acute persistent cough in school-age children and adults whooping cough? A prospective case series study

BACKGROUND

Pertussis is a vaccine modified disease in most age groups and hence subtle in its presentation. Current diagnostic approaches require relatively invasive sampling.

AIM

To determine the incidence of B. pertussis infection among people aged 5-49 years identified in primary care with acute persistent cough using an oral fluid based diagnostic test.

DESIGN AND SETTING

Active surveillance of acute persistent cough of 2 weeks duration or greater was established in Auckland, New Zealand from May to October 2011. The 15 participating primary care practices provided care for a socioeconomically diverse population.

METHOD

Recent B. pertussis infection was determined by measurement of IgG antibodies to pertussis toxin (PT) in an oral fluid sample. An IgG antibody titre to PT of ≥70 arbitrary units defined recent infection. Participants reported symptoms at presentation and kept a cough diary.

RESULTS

A total of 226 participants were enrolled: 70 (31%) were children (5-16 years) and 156 (69%) were adults (17-49 years). Oral fluid samples were obtained from 225 participants. Ten per cent (23/225) had recent B. pertussis infection including a larger proportion of children than adults (17% versus 7%, P = 0.003). Neither cough duration nor any individual symptom discriminated between those with and without recent B. pertussis infection.

CONCLUSION

Pertussis is a frequent cause of acute persistent cough presenting to primary care. Clinical differentiation of pertussis from other causes of acute persistent cough is difficult. An oral fluid based diagnostic test, which is less invasive than other diagnostic approaches, has high acceptability in primary care.

Geographical differences in whooping cough in Catalonia, Spain, from 1990 to 2010

Background

Whooping cough is a communicable disease whose incidence has increased in recent years in some countries with vaccination. Since 1981, in Catalonia (Spain), cases must be reported to the Public Health Department. In 1997, surveillance changed from aggregated counts to individual report and the surveillance system was improved after 2002. Catalan public health is universal with equal coverage geographically. The aim of this study was to determine whether there are differences in whooping cough incidence in rural and urban counties.

Methods

Cases in 1990–2010 were classified as rural or urban. Incidences and risk ratios (RR) between urban and rural counties and 95% CI were calculated. Associations between rural and urban counties and structural changes during the study period were analysed.

Results

Twelve years of the whole study period showed differences in incidence between rural and urban counties. The incidence was higher in urban counties in seven years and rural counties in five years. There was a positive association of whooping cough incidence in rural and urban counties in four-week periods. Structural changes were detected in the following four-week periods: 4^th in 1993, 7^th in 1996 and 3^rd 2005 in rural counties and 5^th 1993, 9^th in 1996 and 8^th in 2007 in urban counties.

Conclusions

Differences in whooping cough between rural and urban counties were found. In most years, the incidence was higher in urban than in rural counties. Rural and urban counties show similar cyclic behaviour when four-week periods were considered.

Booster vaccination: the role of reduced antigen content vaccines as a preschool booster

The need for boosters for tetanus, diphtheria, pertussis, and polio, starting from preschool age, is related to the waning immune protection conferred by vaccination, the elimination/reduction of natural boosters due to large-scale immunization programs, and the possibility of reintroduction of wild agents from endemic areas. Taking into account the relevance of safety/tolerability in the compliance with vaccination among the population, it have been assessed whether today enough scientific evidences are available to support the use of dTap-IPV booster in preschool age. The review of the literature was conducted using the PubMed search engine. A total of 41 works has been selected; besides, the documentation produced by the World Health Organization, the European Centre for Disease Control, and the Italian Ministry of Health has been consulted. Many recent papers confirm the opportunity to use a low antigenic dose vaccine starting from 4 to 6 years of age. There is also evidence that 10 years after immunization the rate of seroprotected subjects against diphtheria does not differ significantly between those vaccinated with paediatric dose (DTaP) or reduced dose (dTaP or dTap) product. The dTpa vaccine is highly immunogenic for diphtheria toxoids regardless of prior vaccination history (2 + 1 and 3 + 1 schedules).

Effectiveness and cost-effectiveness of different immunization strategies against whooping cough to reduce child morbidity and mortality

INTRODUCTION

In the last years there has been a significant increase in reported cases of pertussis in developed countries, in spite of high rates of childhood immunization. Health institutions have recommended different vaccination strategies to reduce child morbidity and mortality: vaccination of adolescents and adults, pregnant women, people in contact with the newborn (cocoon strategy) and health care workers. The aim of this paper is to review the scientific evidence supporting these recommendations.

METHODS

Systematic review on the effectiveness and cost-effectiveness of the above strategies for the reduction of morbidity and mortality from pertussis in infants under 12 months. The electronic databases Medline, PreMedline, Embase, CRD, Cochrane Central, and Trip Database were consulted from 1990 to October 2012. The evidence was assessed using the GRADE system.

RESULTS

There were eight studies on the efficacy or safety of the strategies analyzed, and 18 economic evaluations. Direct evidence on the efficacy of these strategies is scarce. Economic evaluations suggest that vaccination of adolescents and adults would be cost-effective, although there is major uncertainty over the parameters used.

CONCLUSIONS

From the perspective of health technology assessment, there is insufficient evidence to recommend the vaccination strategies evaluated.

Combined hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus-Haemophilus influenzae type B vaccine; Infanrix™ hexa: twelve years of experience in Italy

Infant vaccination using 2-dose priming at 3 and 5 mo of age with a booster at 11–12 mo of age was pioneered in Italy. The 3-5-11 schedule is now used in a growing number of European countries. Infanrix™ hexa (DTPa-HBV-IPV/Hib, GlaxoSmithKline Vaccines) was first licensed for use in 2000 and has been the only pediatric hexavalent vaccine available since 2005. We reviewed available clinical trial data describing the immunogenicity of DTPa-HBV-IPV/Hib when administered at 3, 5, and 11 mo of age, and conducted an analysis of safety using global and Italian post-marketing surveillance data. In Italy, DTPa-HBV-IPV/Hib has a demonstrated safety record extending over a decade of use, it has been associated with record levels of vaccine coverage, and with sustained disease control in vaccinated cohorts. Hexavalent vaccines will continue to contribute to high vaccine coverage in Italy and across Europe.

Pertussis: a review of disease epidemiology worldwide and in Italy

Pertussis continues to be a relevant public-health issue. The high coverage rates achieved have decreased the spread of the pathogen, but the waning of immunity implies a relevant role of adolescents and adults in the infective dynamics as they may represent a significant source of infection for unvaccinated or incompletely immunized newborns. The passive surveillance system is affected by many limitations. The underestimation of pertussis in adolescents, young adults and adults is mainly related to the atypical clinical characteristics of cases and the lack of lab confirmation. The real epidemiological impact of pertussis is not always perceived, anyway, the unavailability of comprehensive data should not hamper the adoption of active prophylactic interventions aimed at preventing the impact of waning immunity on pertussis. To avoid an increase of the mean age of acquisition of the infection, a booster dose of low-antigen content combined vaccine should be adopted in adolescents and adults. A decreased risk of infection in newborns can be achieved with the cocoon strategy, although the debate on this aspect is still open and enhanced surveillance and further studies are needed to fine-tune the pertussis prevention strategy.

Pertussis infections and vaccinations in Bolivia, Brazil and Mexico from 1980 to 2009

Global coverage with three doses of the diphtheria, tetanus and pertussis vaccine (DTP3) increased from less than 5% in 1974 to 82% in 2009 due to worldwide focus on universal vaccination. Nonetheless, pertussis remains the fifth-leading cause of vaccine-preventable deaths. This study examines DTP3 vaccination from 1980 through 2009 in three countries within Latin America, Bolivia, Brazil and Mexico, selected for their distinct health care systems and vaccination strategies. Similar to global trends, these nations have achieved dramatic improvements in pertussis immunization. In Bolivia, immunization rates increased from 11% to 85%; in Brazil, rates increased from 37% to 97%; and in Mexico, the immunization rates increased from 44% to 72%. Pertussis infections have concomitantly decreased from 1980 to 2009. In Bolivia, cases decreased from 44.4 per 100,000 people to zero reported cases. In Brazil, the incidence decreased from 37.6 to 0.5 cases per 100,000. The incidence in Mexico decreased from 8.2 to 0.5 cases per 100,000. In order to increase vaccination rates further, health systems must continue to raise awareness about disease prevention, expand health surveillance systems, and improve access to health services.