Cost-effectiveness of adult pertussis vaccination in Germany

How the Timing of Annual COVID-19 Vaccination of Nursing Home Residents and Staff Affects Its Value

OBJECTIVES

To evaluate the epidemiologic, clinical, and economic value of an annual nursing home (NH) COVID-19 vaccine campaign and the impact of when vaccination starts.

DESIGN

Agent-based model representing a typical NH.

SETTING AND PARTICIPANTS

NH residents and staff.

METHODS

We used the model representing an NH with 100 residents, its staff, their interactions, COVID-19 spread, and its health and economic outcomes to evaluate the epidemiologic, clinical, and economic value of varying schedules of annual COVID-19 vaccine campaigns.

RESULTS

Across a range of scenarios with a 60% vaccine efficacy that wanes starting 4 months after protection onset, vaccination was cost saving or cost-effective when initiated in the late summer or early fall. Annual vaccination averted 102 to 105 COVID-19 cases when 30-day vaccination campaigns began between July and October (varying with vaccination start), decreasing to 97 and 85 cases when starting in November and December, respectively. Starting vaccination between July and December saved $3340 to $4363 and $64,375 to $77,548 from the Centers for Medicare & Medicaid Services and societal perspectives, respectively (varying with vaccination start). Vaccination's value did not change when varying the COVID-19 peak between December and February. The ideal vaccine campaign timing was not affected by reducing COVID-19 levels in the community, or varying transmission probability, preexisting immunity, or COVID-19 severity. However, if vaccine efficacy wanes more quickly (over 1 month), earlier vaccination in July resulted in more cases compared with vaccinating later in October.

CONCLUSIONS AND IMPLICATIONS

Annual vaccination of NH staff and residents averted the most cases when initiated in the late summer through early fall, at least 2 months before the COVID-19 winter peak but remained cost saving or cost-effective when it starts in the same month as the peak. This supports tethering COVID vaccination to seasonal influenza campaigns (typically in September-October) for providing protection against SARS-CoV-2 winter surges in NHs.

Burden of Pertussis in COPD: A Retrospective Database Study in England

Chronic obstructive pulmonary disease (COPD) may increase the risk and severity of pertussis infection. Health care resource utilization (HCRU) and direct medical costs (DMC) of treating pertussis among patients with COPD are unknown. Reported incidence of pertussis among individuals aged ≥ 50 years with COPD was assessed in Clinical Practice Research Datalink and Hospital Episode Statistics databases during 2009-2018 using a retrospective cohort design. HCRU and DMC from the National Health Service perspective were compared between patients with COPD and pertussis and propensity score-matched patients with COPD without pertussis. Seventy-eight new pertussis events were identified among 387 086 patients with COPD aged ≥ 50 years (incidence rate: 4.73; 95% confidence interval 3.74-5.91 per 100 000 person-years). HCRU and DMC were assessed among 67 patients with COPD and pertussis and 267 matched controls. During the month before the pertussis diagnosis, the rates of general practitioner (GP)/nurse visits (4289 vs. 1774 per 100 patient-years) and accident and emergency visits (182 vs. 18 per 100 patient-years) were higher in the pertussis cohort; GP/nurse visits (2935 vs. 1705 per 100 patient-years) were also higher during the following 2 months (all p < 0.001). During the month before the pertussis diagnosis, annualized per-patient total DMC were £2012 higher in the pertussis cohort (£3729 vs. £1717; p < 0.001); during the following 2 months, they were £2407 higher (£5498 vs. £3091; p < 0.001). In conclusion, a pertussis episode among individuals with COPD resulted in significant increases in HCRU and DMC around the pertussis event.

Tetanus, diphtheria and acellular pertussis (Tdap) vaccine for prevention of pertussis among adults aged 19 years and older in the United States: A cost-effectiveness analysis

Currently, the Advisory Committee on Immunization Practices recommends one-time tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccination for all adults 19 years and older. This study is designed to evaluate the cost-effectiveness of Tdap vaccination for Tdap-eligible adults aged 19 through 85 in the United States. A cost-effectiveness model was developed to compute costs and health outcomes associated with pertussis among 100,000 Tdap-eligible persons of each age cohort. From the societal perspective, the cost per quality-adjusted life-year (QALY) saved was evaluated under the vaccination scenarios. Sensitivity analyses were also conducted to evaluate the impacts of changes in key variables. All costs were adjusted to 2018 US$ with an annual discount rate of 3% applied to costs and outcomes. The incremental cost-effectiveness ratios (ICERs) for vaccinating US adults aged 19 to 85 with Tdap ranged from $248,000/QALY to $900,000/QALY. The lowest cost per QALY was found to be $248,000 for the age 65 cohort, followed by $332,000 for the cohort of age 19, and followed by $477,000 for the age 50 cohort. Sensitivity analysis showed the most dramatic changes in ICER occurred when changing the underreporting factor, vaccine effectiveness and vaccination costs. While Tdap vaccination may not be as cost effective as predicted earlier, it remains the best available preventive measure against pertussis. Further investigation of the true burden of pertussis disease among adults and the effectiveness of Tdap vaccination in this population is needed to better estimate the impact of Tdap vaccination.

Towards adult vaccination in India: a narrative literature review

Despite vast improvements in childhood vaccination coverage in India, adult vaccination coverage is negligible. Our aim was, therefore, to create awareness about the importance of adult immunization. Although the true burden of vaccine-preventable diseases (VPDs) among Indian adults is unknown, adults are particularly vulnerable during outbreaks, due to a lack of immunization, waning immunity, age-related factors (e.g. chronic conditions and immunosenescence), and epidemiological shift. There are no national adult immunization guidelines in India, and although several medical societies have published adult immunization guidelines, these vary, making it unclear who should receive which vaccines (based on age, underlying conditions, etc.). Other barriers to adult immunization include vaccine hesitancy, missed opportunities, and cost. Steps to improve adult vaccination could include: adoption of national guidelines, education of healthcare providers and the public, and promotion of life-course immunization. Improving adult vaccine coverage could help reduce the burden of VPDs, particularly among older adults.

Cost-effectiveness analysis of universal adult immunization with tetanus-diphtheria-acellular pertussis vaccine (Tdap) versus current practice in Brazil

BACKGROUND

A pertussis outbreak occurred in Brazil from 2011 to 2014, despite high coverage of whole-cell pertussis containing vaccines in early childhood. Infants were the most affected. This study aimed to evaluate the cost-effectiveness of introducing universal adult vaccination with Tdap into the National Immunization Program in Brazil.

METHODS

Economic evaluation using a dynamic model to compare two strategies: (1) universal vaccination with single dose of Tdap at 20 years of age and (2) current practice (only pregnant women pertussis vaccination). The health system perspective was adopted. Temporal horizon was 10 years. Discount rate of 5% was applied to costs and benefits. Vaccine effectiveness (VE) was obtained from a population-based observational study. Epidemiological, resource utilization and cost estimates were obtained from the Brazilian Health Information Systems. The primary outcome was cost per life year saved (LYS), based on life expectancy at birth in Brazil in 2015. Univariate and multivariate sensitivity analysis were performed.

RESULTS

Adult vaccination with VE of 82.6% and coverage of 40%, at price of US$7.01 per dose, and assuming herd protection would avoid 167 infant deaths by pertussis, saving 12,325 years of life and costing a total of US$105495891.61, from the health system perspective. The universal immunization would result in ICER of US$8459.13. The results were highly sensitive to disease incidence.

CONCLUSIONS

The results suggest that universal adult vaccination with Tdap would not be a cost-effective intervention for preventing pertussis cases and deaths in infants in Brazil.

Economic evaluation of adolescents and adults' pertussis vaccination: A systematic review of current strategies

The reemergence of pertussis in the last two decades led to the introduction of adolescents and adults immunization strategies of tetanus–diphtheria–acellular pertussis vaccines (Tdap) in several countries. The health authorities must consider economic aspects when deciding to recommend and fund new programs. Here we present a systematic review of worldwide full economic evaluations of pertussis vaccination targeting adolescents or adults published from 2000. Studies were identified by searching MEDLINE, Excerpta Medica, CRD, and Lilacs databases. Twenty-seven economic evaluations of different strategies with Tdap were identified. Booster vaccination for adolescents and adults were the most frequent, followed by cocooning and pregnant women vaccination. Strategies performance varied considerably among different studies. Assumptions regarding underreporting correction, herd protection and vaccine coverage were crucial to cost-effectiveness results. Understanding the model and the parameters used is essential to understand the results, and identify the major issues important to public health decisions.

Is adding maternal vaccination to prevent whooping cough cost-effective in Australia?

Pertussis or whooping cough, a highly infectious respiratory infection, causes significant morbidity and mortality in infants. In adolescents and adults, pertussis presents with atypical symptoms often resulting in under-diagnosis and under-reporting, increasing the risk of transmission to more vulnerable groups. Maternal vaccination against pertussis protects mothers and newborns. This evaluation assessed the cost-effectiveness of adding maternal dTpa (reduced antigen diphtheria, Tetanus, acellular pertussis) vaccination to the 2016 nationally-funded pertussis program (DTPa [Diphtheria, Tetanus, acellular Pertussis] at 2, 4, 6, 18 months, 4 years and dTpa at 12–13 years) in Australia.

A static cross-sectional population model was developed using a one-year period at steady-state. The model considered the total Australian population, stratified by age. Vaccine effectiveness against pertussis infection was assumed to be 92% in mothers and 91% in newborns, based on observational and case-control studies. The model included conservative assumptions around unreported cases.

With 70% coverage, adding maternal vaccination to the existing pertussis program would prevent 8,847 pertussis cases, 422 outpatient cases, 146 hospitalizations and 0.54 deaths per year at the population level. With a 5% discount rate, 138.5 quality-adjusted life-years (QALYs) would be gained at an extra cost of AUS$ 4.44 million and an incremental cost-effectiveness ratio of AUS$ 32,065 per QALY gained. Sensitivity and scenario analyses demonstrated that outcomes were most sensitive to assumptions around vaccine effectiveness, duration of protection in mothers, and disutility of unreported cases.

In conclusion, dTpa vaccination in the third trimester of pregnancy is likely to be cost-effective from a healthcare payer perspective in Australia.

Inclusion of the value of herd immunity in economic evaluations of vaccines. A systematic review of methods used

OBJECTIVE

The objectives of this review were to identify vaccine economic evaluations that include herd immunity and describe the methodological approaches used.

METHODS

We used Kim and Goldie's search strategy from a systematic review (1976-2007) of modelling approaches used in vaccine economic evaluations and additionally searched PubMed/MEDLINE and Embase for 2007-2015. Studies were classified according to modelling approach used. Methods for estimating herd immunity effects were described, in particular for the static models.

RESULTS

We identified 625 economic evaluations of vaccines against human-transmissible diseases from 1976 to 2015. Of these, 172 (28%) included herd immunity. While 4% of studies included herd immunity in 2001, 53% of those published in 2015 did this. Pneumococcal, human papilloma and rotavirus vaccines represented the majority of studies (63%) considering herd immunity. Ninety-five of the 172 studies utilised a static model, 59 applied a dynamic model, eight a hybrid model and ten did not clearly state which method was used. Relatively crude methods and assumptions were used in the majority of the static model studies.

CONCLUSION

The proportion of economic evaluations using a dynamic model has increased in recent years. However, 55% of the included studies used a static model for estimating herd immunity. Values from a static model can only be considered reliable if high quality surveillance data are incorporated into the analysis. Without this, the results are questionable and they should only be included in sensitivity analysis.

Economic impact of thermostable vaccines

BACKGROUND

While our previous work has shown that replacing existing vaccines with thermostable vaccines can relieve bottlenecks in vaccine supply chains and thus increase vaccine availability, the question remains whether this benefit would outweigh the additional cost of thermostable formulations.

METHODS

Using HERMES simulation models of the vaccine supply chains for the Republic of Benin, the state of Bihar (India), and Niger, we simulated replacing different existing vaccines with thermostable formulations and determined the resulting clinical and economic impact. Costs measured included the costs of vaccines, logistics, and disease outcomes averted.

RESULTS

Replacing a particular vaccine with a thermostable version yielded cost savings in many cases even when charging a price premium (two or three times the current vaccine price). For example, replacing the current pentavalent vaccine with a thermostable version without increasing the vaccine price saved from $366 to $10,945 per 100 members of the vaccine's target population. Doubling the vaccine price still resulted in cost savings that ranged from $300 to $10,706, and tripling the vaccine price resulted in cost savings from $234 to $10,468. As another example, a thermostable rotavirus vaccine (RV) at its current (year) price saved between $131 and $1065. Doubling and tripling the thermostable rotavirus price resulted in cost savings ranging from $102 to $936 and $73 to $808, respectively. Switching to thermostable formulations was highly cost-effective or cost-effective in most scenarios explored.

CONCLUSION

Medical cost and productivity savings could outweigh even significant price premiums charged for thermostable formulations of vaccines, providing support for their use.

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

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

Pertussis post-exposure prophylaxis among household contacts: a cost-utility analysis

Background

Recent pertussis outbreaks have prompted re-examination of post-exposure prophylaxis (PEP) strategies, when immunization is not immediately protective. Chemoprophylaxis is recommended to household contacts; however there are concerns of clinical failure and significant adverse events, especially with erythromycin among infants who have the highest disease burden. Newer macrolides offer fewer side effects at higher drug costs. We sought to determine the cost-effectiveness of PEP strategies from the health care payer perspective.

Methods

A Markov model was constructed to examine 4 mutually exclusive strategies: erythromycin, azithromycin, clarithromycin, or no intervention, stratified by age group of contacts (“infant”, “child”, and “adult”). Transition probabilities, costs and quality-adjusted life years (QALYs) were derived from the literature. Chronic neurologic sequelae were modeled over a lifetime, with costs and QALYs discounted at 5%. Associated health outcomes and costs were compared, and incremental cost-effectiveness ratios (ICER) were calculated in 2012 Canadian dollars. Deterministic and probabilistic sensitivity analyses were performed to evaluate the degree of uncertainty in the results.

Findings

Azithromycin offered the highest QALYs in all scenarios. While this was the dominant strategy among infants, it produced an ICER of $16,963 per QALY among children and $2,415 per QALY among adults. Total QALYs with azithromycin were 19.7 for a 5-kg infant, 19.4 for a 10-year-old child, and 18.8 for a 30-year-old adult. The costs of azithromycin PEP among infants, children and adults were $1,976, $132 and $90, respectively. While results were sensitive to changes in PEP effectiveness (11% to 87%), disease transmission (variable among age groups) and hospitalization costs ($379 to $59,644), the choice of strategy remained unchanged.

Interpretation

Pertussis PEP is a cost-effective strategy compared with no intervention and plays an important role in contact management, potentially in outbreak situations. From a healthcare payer perspective, azithromycin is the optimal strategy among all contact groups.

Duration of pertussis immunity after DTaP immunization: a meta-analysis

BACKGROUND AND OBJECTIVES

Pertussis incidence is increasing, possibly due to the introduction of acellular vaccines, which may have decreased the durability of immune response. We sought to evaluate and compare the duration of protective immunity conferred by a childhood immunization series with 3 or 5 doses of diphtheria-tetanus-acellular pertussis (DTaP).

METHODS

We searched Medline and Embase for articles published before October 10, 2013. Included studies contained a measure of long-term immunity to pertussis after 3 or 5 doses of DTaP. Twelve articles were eligible for inclusion; 11 of these were included in the meta-analysis. We assessed study quality and used meta-regression models to evaluate the relationship between the odds of pertussis and time since last dose of DTaP and to estimate the probability of vaccine failure through time.

RESULTS

We found no significant difference between the annual odds of pertussis for the 3- versus 5-dose DTaP regimens. For every additional year after the last dose of DTaP, the odds of pertussis increased by 1.33 times (95% confidence interval: 1.23-1.43). Assuming 85% vaccine efficacy, we estimated that 10% of children vaccinated with DTaP would be immune to pertussis 8.5 years after the last dose. Limitations included the statistical model extrapolated from data and the different study designs included, most of which were observational study designs.

CONCLUSIONS

Although acellular pertussis vaccines are considered safer, the adoption of these vaccines may necessitate earlier booster vaccination and repeated boosting strategies to achieve necessary "herd effects" to control the spread of pertussis.

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.

Cost-effectiveness analysis of a pertussis vaccination programme for Japan considering intergenerational infection

OBJECTIVE

The incidence of pertussis in adolescence and adulthood has been increasing, and pertussis outbreaks have occurred sporadically in Japan. The risk of intergenerational infection of pertussis is of concern. The aim of this study is to assess the cost-effectiveness of alternative vaccination programmes for replacing the conventional diphtheria-tetanus (DT) vaccine programme administered in adolescence, considering the risk of intergenerational infection.

METHODS

We examined the cost-effectiveness of 4 pertussis vaccination programmes: (1) one-time adolescent DT vaccination (DT); (2) one-time adolescent DT-acellular pertussis (DTaP) vaccination; (3) one-time adolescent DTaP with decennial booster (DTaP+booster); and (4) one-time adolescent DTaP with additional vaccination targeted at parents with infants (additional DTaP for parents). We adapted a state-transition Markov model to estimate the costs and effectiveness of vaccination in the adolescent and adult cohorts and then considered intergenerational infection from adolescents/adults to infants. We assumed a societal perspective to estimate results and expressed these in terms of cost, life expectancy, quality-adjusted life expectancy, benefit-cost ratio (BCR), and incremental cost-effectiveness ratio (ICER).

RESULTS

At an incidence of 25 per 100,000, the ICERs of the DTaP and additional DTaP for parents strategies were 3,576,072 JPY and 240,055,273 JPY, respectively, when intergenerational transmission of infection was considered. The ICER for the DTaP+booster strategy was dominated.

MAJOR CONCLUSION

Alternative vaccination programmes are not currently cost-effective. If intergenerational infection considered, one-time adolescent DTaP vaccination is cost-effective. More accurate reports of pertussis incidence are required as the results of cost-effectiveness analyses of vaccination vary greatly depending on incidence.

Improving adherence rates to a cocooning program: a pilot experience in Italy

Cocoon is defined as a strategy to reduce the risk for transmission of pertussis to newborn infants by vaccinating household members including parents and siblings. Programmatic challenges make implementation of cocooning program complex. At the local health care unit “ASL Napoli 1 Centro,” a one-year pilot project to evaluate the newborn contacts adherence to a cocoon strategy was started on May, 1st 2011. Healthcare providers (HCPs) offered for free a dTpa booster dose to newborns parents (mothers were immunized after delivery) and household contacts. Until June 30th, overall only 7 dTpa booster doses out of 261 newborns (2.6%) were administered for cocooning. Then, an improvement in communication strategy to the families was introduced by preparing specific information leaflets, increasing the HCPs devoted to the cocoon, and focusing the interaction with families during the visiting time at the maternity ward. Overall, 601 out of 762 (78,8%) contacted new mothers received dTpa booster. Cocoon high acceptance rates could be reached providing that proper communication tools and enough skilled HCPs were engaged in the interaction with the families. This report is, to our knowledge, the first to document successful implementation of pertussis cocooning in an Italian setting.

Use of models to identify cost-effective interventions: pertussis vaccination for pediatric health care workers

OBJECTIVE

Acellular pertussis vaccine is safe and effective in adults. An explicit recommendation for pertussis booster vaccination in pediatric health care workers is based on the importance of health care workers as a potential source of infection for patients. However, limited information is available on the economic attractiveness of this intervention. We sought to evaluate the health-economic attractiveness of a diphtheria-tetanus-acellular pertussis booster vaccination program for health care workers in a pediatric intensive care setting.

METHODS

We developed a Markov model to calculate the cost-effectiveness of vaccinating NICU health care workers in different proportions ranging from the current strategy of no pertussis booster vaccination program to a vaccination program that achieves between 25% and 95% vaccine coverage.

RESULTS

Implementation of a vaccination program that achieves 25% coverage was projected to be cost-saving compared with no vaccine program. At all coverage levels the intervention reduced costs, increased life expectancy, and was cost-effective. Projections were most sensitive to the risk of a pertussis introduction via an infected health care worker. Once the monthly risk of an introduction exceeded ∼0.3%, implementation of an immunization program with at least 25% coverage provided both greater health and greater economic benefits than having no vaccine program.

CONCLUSIONS

The implementation of a hospital-based and funded diphtheria-tetanus-acellular pertussis vaccine program administered through an occupational health program is cost-effective or cost-saving in the context of pediatric health care facilities in which many of the patients are at risk of serious morbidity and mortality should they acquire pertussis while hospitalized.

[Pertussis vaccination for parents: proposal and evaluation of two professional practices in a maternity hospital]

BACKGROUND

Despite good rates of immunization among children, an apparent increase in the incidence of pertussis disease in infants in France has been observed, mainly because of low vaccination coverage among adults. Guidelines drawn up in 2004 recommend a vaccination strategy called cocooning for parents, but those guidelines are rarely followed by the medical community. Raising the vaccination rate among parents to 65% and the extension of pertussis vaccine booster for people between 26 and 28 years old could help control the disease.

OBJECTIVE AND METHODS

In a primary healthcare setting in 2009, we studied 2 groups of 188 and 190 parents of newborns in a maternity unit. We proposed 2 strategies: information and vaccine prescription for both parents (if eligible) at the time of discharge from the maternity unit (group 1) or vaccination proposed to both parents during hospitalization in the maternity unit (group 2). After 6 weeks, the vaccination rates of both groups were compared.

RESULTS

Analysis shows that parents had insufficient knowledge of the disease. Parents were often unaware of their vaccination status. Hence, objective data concerning the vaccination status was quickly available for only 42% of the population, making determination of eligibility unreliable. Only 8% of the parents were up to date for pertussis vaccination in the last 10 years, whereas 90% of the parents had the opportunity for vaccination and 37% of them had been eligible before the pregnancy. At the end of the study, 53% of the parents in group 1 were vaccinated, showing the positive impact of the medical encounter and vaccine prescription. During the study, 40% of the parents in group 2 who were proposed immediate vaccination in the maternity unit accepted it. This increased to 43% of group 2 parents being immunized by the time they had left the maternity unit. Proposing the vaccination at the maternity hospital was the more effective of the 2 strategies (P=0.03): at the end of the study, the objective was nearly reached with 64% of the parents being vaccinated.

CONCLUSIONS

The promotion of parental vaccination by the pediatrician in the maternity ward is simple and effective. Medical encounters resulting from prescriptions made during hospitalization could raise awareness in general practitioners and enable them to identify eligible adults for pertussis vaccination and vaccinate themselves. There is a need to discuss the complementarity and interactions between perinatal teams and general practitioners within the community healthcare network.

Tdap5 vaccine (Covaxis): a review of its use as a single-booster immunization for the prevention of tetanus, diphtheria, and pertussis in children (aged 4 years), adolescents, and adults

Covaxis (also licensed as Triaxis or Adacel in individual countries) is a combined tetanus toxoid, reduced diphtheria toxoid, five component acellular pertussis (namely detoxified pertussis toxin, filamentous hemagglutinin, pertactin, and fimbriae types 2 and 3) vaccine for the prevention of diphtheria, tetanus, and pertussis. It is approved for use in Europe as a single intramuscular booster dose in children (aged ≥ 4 years), adolescents, and adults, and in the US it is approved for use in individuals aged 11-64 years. In large, randomized, controlled clinical trials conducted in the UK and North America, a single intramuscular booster dose of Covaxis induced robust immune responses for all of its component antigens when given to children (aged ≥ 4 years), adolescents, and adults. In addition, Covaxis vaccine was safe and generally well tolerated in terms of solicited and unsolicited local injection-site and systemic adverse events, most of which were of mild intensity and resolved without sequelae. Furthermore, the immunogenicity of each individual component and the reactogenicity of Covaxis vaccine in children, adolescents, and adults was generally similar to that of comparator vaccines. Despite being a vaccine-preventable disease and having >90% primary vaccination coverage worldwide, pertussis remains uncontrolled, particularly amongst adolescents and adults. Given the changing epidemiology of pertussis and the requirement to reduce infection in adolescents and adults (including healthcare workers) and thereby prevent transmission of the disease from these individuals to very young infants, the new 'cocoon strategy' recommended in current vaccination guidelines has become a key strategy in the management of morbidity and mortality associated with pertussis. This strategy focuses on the immunization of healthcare workers, and the parents and family members of infants who are too young to have undergone primary immunization, so as to prevent the transmission of pertussis to these young at-risk infants. The implementation of the 'cocoon strategy' may finally give countries the ability to control pertussis infections in these at-risk infants and ultimately provide the desired herd immunity against pertussis. In line with this strategy, a booster dose of Covaxis vaccine provides a valuable option to reduce pertussis morbidity and mortality, and to maintain seroprotection against diphtheria and tetanus in children (aged ≥ 4 years), adolescents, and adults.

Cost-effectiveness analysis of various pertussis vaccination strategies primarily aimed at protecting infants in the Netherlands

BACKGROUND

Pertussis is a highly contagious respiratory disease. Despite a high rate of vaccine coverage through the Dutch national immunization program, the incidence of pertussis remains high in the Netherlands and the risk of infection continues. Because pertussis is most severe in unimmunized infants and infants who have only received some of the recommended doses, new pertussis immunization strategies should be considered to protect this vulnerable population.

OBJECTIVE

This study was designed to estimate the cost-effectiveness of 3 new immunization strategies for possible addition to the current Dutch national immunization program: immunization of the infant at birth, immunization of the parents immediately after birth of the child (cocooning), and maternal immunization during the third trimester of pregnancy.

METHODS

A literature search was performed in the PubMed database for articles published in English, German, and Dutch using the following terms: pertussis, whooping cough, vaccination strategies, maternal immunization, cocooning, at birth, vaccine efficacy, mortality, underreporting, prevalence, incidence, and cost-effectiveness. A decision-tree model was developed for this analysis, and data on pertussis morbidity and costs were collected consistently for different age groups (infants <1 year of age and adults 25 to 34 years of age). The size of the infant cohort was set at 200,000 to approximate previous Dutch birth cohorts. The size of the adult cohort was set at 401,380 parents for the cocooning strategy and 201,380 mothers for the maternal immunization strategy. Health benefits (quality-adjusted life-years [QALYs]) and costs were estimated in both cohorts for each of the 3 immunization strate- gies. Incremental cost-effectiveness ratios were calculated from both a payer's and a societal perspective. The robustness of the results was determined through sensitivity analysis.

RESULTS

In the base-case analysis, cocooning and maternal immunization were found to be effective in reducing the incidence of pertussis among infants (123 and 174 infant cases were expected to be prevented, respectively). Furthermore, cocooning and maternal immunization were estimated to be cost-effective from a payer's perspective (euro4600 [US $6400]/QALY and euro3500 [$4900]/QALY, respectively) and even cost-saving from a societal perspective (savings of up to euro7200 [$10,100] and euro5000 [$7000], respectively). Sensitivity analyses revealed that favorable cost-effectiveness was generally robust. In the sensitivity analysis, the cost-effectiveness of cocooning and maternal immunization was mostly sensitive for changes in assumptions on underreporting (200-fold increase in reported number of symptomatic cases) of pertussis disease and infection. With no underreporting, the ICER was estimated at euro211,900 ($296,700)/QALY for cocooning and euro81,600 ($114,200)/QALY for maternal immunization from a payer's perspective. However, even at much lower levels of underreporting (20- to 30-fold increase in incidence), cost-effectiveness remained favorable. The cost-effectiveness of the third strategy, at-birth immunization, was highly unfavorable (euro329,900 [$461,900]/QALY from a payer's perspective and euro330,100 [$462,100]/ QALY from a societal perspective).

CONCLUSIONS

This study estimated that the addition of cocooning or maternal immunization to the current Dutch national immunization program likely would be cost-effective or even cost-saving. These estimates were mainly due to reduction in the number of cases among parents, which are likely to be mild and therefore would largely remain unreported. Immunization at birth was not a cost-effective strategy. Cocooning was the most expensive intervention to implement; however, it resulted in the highest number of QALYs gained (mainly in adults). Maternal immunization would offer better protection of infants, due to maternally acquired antibodies.

Cost-effectiveness of adolescent pertussis vaccination for the Netherlands: using an individual-based dynamic model

BACKGROUND

Despite widespread immunization programs, a clear increase in pertussis incidence is apparent in many developed countries during the last decades. Consequently, additional immunization strategies are considered to reduce the burden of disease. The aim of this study is to design an individual-based stochastic dynamic framework to model pertussis transmission in the population in order to predict the epidemiologic and economic consequences of the implementation of universal booster vaccination programs. Using this framework, we estimate the cost-effectiveness of universal adolescent pertussis booster vaccination at the age of 12 years in the Netherlands.

METHODS/PRINCIPAL FINDINGS

We designed a discrete event simulation (DES) model to predict the epidemiological and economic consequences of implementing universal adolescent booster vaccination. We used national age-specific notification data over the period 1996-2000--corrected for underreporting--to calibrate the model assuming a steady state situation. Subsequently, booster vaccination was introduced. Input parameters of the model were derived from literature, national data sources (e.g. costing data, incidence and hospitalization data) and expert opinions. As there is no consensus on the duration of immunity acquired by natural infection, we considered two scenarios for this duration of protection (i.e. 8 and 15 years). In both scenarios, total pertussis incidence decreased as a result of adolescent vaccination. From a societal perspective, the cost-effectiveness was estimated at €4418/QALY (range: 3205-6364 € per QALY) and €6371/QALY (range: 4139-9549 € per QALY) for the 8- and 15-year protection scenarios, respectively. Sensitivity analyses revealed that the outcomes are most sensitive to the quality of life weights used for pertussis disease.

CONCLUSIONS/SIGNIFICANCE

To our knowledge we designed the first individual-based dynamic framework to model pertussis transmission in the population. This study indicates that adolescent pertussis vaccination is likely to be a cost-effective intervention for The Netherlands. The model is suited to investigate further pertussis booster vaccination strategies.

Boostrix: a reduced-dose acellular pertussis vaccine for use in adolescents and adults

Pertussis remains a serious problem in many countries. Even in countries with high vaccine coverage and a long vaccination history, pertussis outbreaks occur periodically. Rather than being a disease of young children, pertussis has shifted to affect adolescents and adults. Increased pertussis burden in adolescents and adults is the major source of severe infection for young infants. An effective vaccine is needed to control the spread of pertussis beyond preschool children. Boostrix is a reduced-dose acellular pertussis vaccine with diphtheria and tetanus toxoids, and is designed for use in adolescents and adults. Current evidence suggests that Boostrix is immunogenic and well tolerated. The pertussis component of Boostrix has been shown to be efficacious in a large-scale Phase III trial. More than 50 countries have given permit to the use of Boostrix, and many of them formally recommend the use of Boostrix in adolescents and adults. Designed as a vaccine for adolescence and adults, Boostrix has a long way to go to achieve large-scale use in those target groups. Nevertheless, we expect that the advent of Boostrix will lead to a much better control of pertussis in the general population.

Conclusions on (cost-)effectiveness of pertussis booster vaccination strategies highly dependent on selections made in evidence review

This letter reacts on a paper recently published in this journal, reviewing the effectiveness and (cost-)effectiveness of pertussis booster vaccination strategies. We argue that a different selection of (cost-)effectiveness data could validly be made than the one presented in the review as being considered most robust. In particular, we explicitly present an alternative set of (cost-)effectiveness data.

Coalition of advocates to vaccinate of Western European citizens aged 60 years and older

The high burden of infectious diseases in adults aged 60 years and older is disproportionate, considering that many of these diseases are vaccine-preventable. Based on careful analysis of the reasons for vaccination barriers/failures in the European population, the two European geriatric and gerontological societies (the European Union Geriatric Medicine Society [EUGMS] and the International Association of Gerontology and Geriatrics - European Region [IAGG-ER]) propose careful adaptation of current vaccine guidelines to promote preventive aspects, concerning both life threatening-diseases (influenza, pneumococcal pneumonia and tetanus/diphtheria) and diseases which adversely impact patients' quality of life (pertussis and herpes zoster). This consensus statement is designed to support official recommendations and improve the willingness to vaccinate the most rapidly growing segment of the population. The following guidelines are based on the importance of the sustainability of vaccine programs from midlife till extreme old age: - Promote healthy aging by optimizing health determinants of daily functions, active participation in society and individual quality of life; - Provide useful information to contribute toward harmonizing vaccine strategies at European level; - Support the public health, social and economic values of vaccination. Both healthcare professionals and consumers associations have a critical role to play in the implementation of such consensus clinical guidelines.

Pertussis: not only a disease of childhood

INTRODUCTION

Pertussis is not just a childhood disease, but a respiratory infection that causes persistent cough in all age groups, from newborns to the elderly.

METHODS

The authors performed a selective literature search and reviewed national and international recommendations for treatment and vaccination.

RESULTS

Pertussis is found principally in young unvaccinated infants, but school-age children, adolescents, and adults are also affected. Up to 1% of infants contract pertussis, and their respiratory symptoms are often accompanied by apnea. School-age children occasionally display the coughing spasms typical of the disease. Annually, 0.2% to 0.5% of all adolescents and adults are infected and suffer from prolonged, frequently non-paroxysmal coughing. Severe and fatal cases of pertussis occur mainly in newborns and infants, and 25% of affected adults experience complications. Bordetella DNA may be detected by polymerase chain reaction (PCR) for four weeks after symptom onset; except in infants, the sensitivity of this diagnostic technique is low. Although the diagnosis can be confirmed by serological tests, the methods are not well standardized. Treatment with a macrolide prevents the spread of infection, but generally does not alleviate the symptoms. Combination vaccines are the most effective means of prophylaxis.

DISCUSSION

Pertussis is usually not included in the differential diagnosis of persistent respiratory symptoms. The considerable burden of disease could be reduced in adults and young infants by vaccinating adults with acellular combination vaccines.