Economic burden of pertussis in children: A single-center analysis in Hangzhou, China.

The "reemergence of pertussis" has elicited international concerns, occurring paradoxically amidst the expansion of immunization programs. This study was aimed to evaluate quantitatively the economic burden and identify the determinants that influence the cost associated with treating pertussis in Chinese children. We evaluated the economic burden by Chinese children diagnosed with pertussis at the Children's Hospital, Zhejiang University School of Medicine in 2022. Direct medical expenses and the utilization of medical resources attributed to pertussis were calculated. A generalized linear regression model was applied to analyze the determinants that were associated with the direct medical expenses among patients. Among the 1110 pertussis patients included in the study, 1060 were outpatients and 50 were inpatients. The average direct medical cost was ¥1878.70(i.e. $279.33). Living in urban areas (OR:1.27, p = .04), complications (OR:1.40, p < .001), hospitalization (OR:10.04, p < .001), and ≥ 3 medical visits (OR:3.71, p < .001) were associated with increased direct medical expenses. Having received four doses of the pertussis vaccine was associated with reduced direct medical expenses (OR:0.81, p = .04). This study underscores a substantial economic burden of pertussis in Hangzhou, with pronounced implications for patients residing in urban areas, experiencing complications, requiring hospitalization, having multiple medical consultations, or lacking comprehensive pertussis vaccination.

Estimation of vaccination coverage from electronic healthcare records; methods performance evaluation - A contribution of the ADVANCE-project.

INTRODUCTION: The Accelerated Development of VAccine beNefit-risk Collaboration in Europe (ADVANCE) is a public private collaboration aiming to develop and test a system for rapid benefit-risk (B/R) monitoring of vaccines, using existing electronic healthcare record (eHR) databases in Europe. Part of the data in such sources is missing due to incomplete follow-up hampering the accurate estimation of vaccination coverage. We compared different methods for coverage estimation from eHR databases; naïve period prevalence, complete case period prevalence, period prevalence adjusted for follow-up time, Kaplan-Meier (KM) analysis and (adjusted) inverse probability weighing (IPW). METHODS: We created simulation scenarios with different proportions of completeness of follow-up. Both completeness independent and dependent from vaccination date and status were considered. The root mean squared error (RMSE) and relative difference between the estimated and true coverage were used to assess the performance of the different methods for each of the scenarios. We included data examples on the vaccination coverage of human papilloma virus and pertussis component containing vaccines from the Spanish BIFAP database. RESULTS: Under completeness independent from vaccination date or status, several methods provided estimates with bias close to zero. However, when dependence between completeness of follow-up and vaccination date or status was present, all methods generated biased estimates. The IPW/CDF methods were generally the least biased. Preference for a specific method should be based on the type of censoring and type of dependence between completeness of follow-up and vaccination. Additional insights into these aspects, might be gained by applying several methods.

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.

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.

Cost-effectiveness of increasing vaccination in high-risk adults aged 18-64 Years: a model-based decision analysis.

BACKGROUND: Adults aged 18-64 years with comorbid conditions are at high risk for complications of certain vaccine-preventable diseases, including influenza and pneumococcal disease. The 4 Pillars™ Practice Transformation Program (4 Pillars Program) increases uptake of pneumococcal polysaccharide vaccine, influenza vaccine and tetanus-diphtheria-acellular pertussis vaccine by 5-10% among adults with high-risk medical conditions, but its cost-effectiveness is unknown. METHODS: A decision tree model estimated the cost-effectiveness of implementing the 4 Pillars Program in primary care practices compared to no program for a population of adults 18-64 years of age at high risk of illness complications over a 10 year time horizon. Vaccination rates and intervention costs were derived from a randomized controlled cluster trial in diverse practices in 2 U.S. cities. One-way and probabilistic sensitivity analyses were conducted. RESULTS: From a third-party payer perspective, which considers direct medical costs, the 4 Pillars Program cost $28,301 per quality-adjusted life year gained; from a societal perspective, which adds direct nonmedical and indirect costs, the program was cost saving and more effective than no intervention. Cost effectiveness results favoring the program were robust in sensitivity analyses. From a public health standpoint, the model predicted that the intervention reduced influenza cases by 1.4%, with smaller decreases in pertussis and pneumococcal disease cases. CONCLUSION: The 4 Pillars Practice Transformation Program is an economically reasonable, and perhaps cost saving, strategy for protecting the health of adults aged < 65 years with high-risk medical conditions.

Cost-effectiveness and programmatic benefits of maternal vaccination against pertussis in England.

BACKGROUND: Maternal pertussis immunisation was introduced during the pertussis resurgence in England in 2012 as a temporary measure to protect infants too young to be vaccinated. The programme was shown to be safe and highly effective. However, continuation of maternal vaccination as a routine programme requires a cost-effectiveness analysis. METHOD: The estimated prevented disease burden among mothers and their infants was obtained assuming 89% (95% CI: 19%-99%) vaccine efficacy for mothers and 91% (95% CI: 84%-95%) for infants. Future incidence was projected based on the disease rates in 2010-2012, including the four-year cycle of low and high incidence years. Full probabilistic sensitivity analysis was performed for different scenarios. RESULTS: Assuming a vaccine coverage of 60%, there were 1650 prevented hospitalisations in infants (3.5% discounting, the first 10 years), including 55-60 deaths and ∼20,500 cases among mothers, of which around 1800 would be severe. The annual costs of the programme are £7.3 million assuming a price of £10 per dose and £9.4 million assuming £15 per dose. Using discounting of 3.5%, a 200 year time horizon and a price of £10 per dose (+£7.5 administration costs) only 25% of the iterations were below £30,000 per QALY. Using a 35% higher incidence resulted in 88% of the scenarios below this threshold. Assuming that the incidence remains at the level at the height of 2012, then the programme would be highly cost effective, with an ICER of £16,865 (£12,209-£25,976; price of £10 and 3.5%/3.5% discounting). CONCLUSION: Maternal vaccination is effective in preventing severe illness and deaths in infants but the cost-effectiveness of the programme is highly dependent on future incidence which is necessarily uncertain. However, the duration and magnitude of protection against transmission afforded by the current acellular vaccines is also uncertain as are the associated effects on future herd immunity. The direct protection offered by the maternal dose provides the only certain way of protecting vulnerable infants from birth.

Cost-effectiveness of next-generation vaccines: The case of pertussis.

Despite steady vaccination coverage rates, pertussis incidence in the United States has continued to rise. This public health challenge has motivated calls for the development of a new vaccine with greater efficacy and duration of protection. Any next-generation vaccine would likely come at a higher cost, and must provide sufficient health benefits beyond those provided by the current vaccine in order to be deemed cost-effective. Using an age-structured transmission model of pertussis, we quantified the health and economic benefits of a next-generation vaccine that would enhance either the efficacy or duration of protection of the childhood series, the duration of the adult booster, or a combination. We developed a metric, the maximum cost-effective price increase (MCPI), to compare the potential value of such improvements. The MCPI estimates the per-dose price increase that would maintain the cost-effectiveness of pertussis vaccination. We evaluated the MCPI across a range of potential single and combined improvements to the pertussis vaccine. As an upper bound, we found that a next-generation vaccine which could achieve perfect efficacy for the childhood series would permit an MCPI of $18 per dose (95% CI: $12-$31). Pertussis vaccine improvements that extend the duration of protection to an average of 75 years would allow for an MCPI of $22 per dose for the childhood series (CI: $10-$33) or $12 for the adult booster (CI: $4-$18). Despite the short duration of the adult booster, improvements to the childhood series could be more valuable than improvements to the adult booster. Combining improvements in both efficacy and duration, a childhood series with perfect efficacy and average duration of 75 years would permit an MCPI of $39 per dose, the highest of any scenario evaluated. Our results highlight the utility of the MCPI metric in evaluating potential vaccines or other interventions when prices are unknown.

Vaccine Timeliness: A Cost Analysis of the Potential Implications of Delayed Pertussis Vaccination in the US.

BACKGROUND: Pertussis infection remains an important public health problem, particularly in infants. Despite high coverage, pertussis vaccination delays can leave infants at a vulnerable age with less protection than anticipated. METHODS: Current diphtheria-tetanus-pertussis (DTaP) vaccination timeliness for the first 3 doses in the US was estimated using National Immunization Survey data. A Markov model estimated the potential impact on outcomes and costs of a hypothetical situation of vaccination at exactly 60, 120 and 180 days, compared with current timeliness. Incidence and unit cost data came from published sources. Age-specific incidence (for month of life) of pertussis and the associated probabilities of hospitalization and death for the US, during 2000-2007, were taken from a recently published US DTaP vaccination cost-effectiveness study. The cost analysis was conducted from the healthcare system's perspective over a 1-year time horizon. A regression analysis was conducted to explore the factors associated with vaccination delay. RESULTS: Current DTaP vaccination was estimated to be delayed by 16, 27 and 44 days, for the first, second and third doses, respectively, relative to vaccination at exactly 60, 120 and 180 days. The model estimated that vaccination at exactly age 60, 120 and 180 days could prevent approximately 278 pertussis cases, 103 hospitalizations and 1 death in infants aged <1 year in the US, gaining approximately 38 quality-adjusted life years and saving approximately $1.03 million in healthcare costs. CONCLUSIONS: Timely administration of infant pertussis vaccine doses could potentially reduce subsequent pertussis cases, hospitalizations, deaths and medical costs in infants aged <1 year in the US.

Estimated Human and Economic Burden of Four Major Adult Vaccine-Preventable Diseases in the United States, 2013.

Low uptake of routinely recommended adult immunizations is a public health concern. Using data from the peer-reviewed literature, government disease-surveillance programs, and the US Census, we developed a customizable model to estimate human and economic burden caused by four major adult vaccine-preventable diseases (VPD) in 2013 in the United States, and for each US state individually. To estimate the number of cases for each adult VPD for a given population, we multiplied age-specific incidence rates obtained from the literature by age-specific 2013 Census population data. We then multiplied the estimated number of cases for a given population by age-specific, estimated medical and indirect (non-medical) costs per case. Adult VPDs examined were: (1) influenza, (2) pneumococcal disease (both invasive disease and pneumonia), (3) herpes zoster (shingles), and (4) pertussis (whooping cough). Sensitivity analyses simulated the impact of various epidemiological scenarios on the total estimated economic burden. Estimated US annual cost for the four adult VPDs was $26.5 billion (B) among adults aged 50 years and older, $15.3B (58 %) of which was attributable to those 65 and older. Among adults 50 and older, influenza, pneumococcal disease, herpes zoster, and pertussis made up $16.0B (60 %), $5.1B (19 %), $5.0B (19 %), and $0.4B (2 %) of the cost, respectively. Among those 65 and older, they made up $8.3B (54 %), $3.8B (25 %), $3.0B (20 %), and 0.2B (1 %) of the cost, respectively. Most (80-85 %) pneumococcal costs stemmed from nonbacteremic pneumococcal pneumonia (NPP). Cost attributable to adult VPD in the United States is substantial. Broadening adult immunization efforts beyond influenza only may help reduce the economic burden of adult VPD, and a pneumococcal vaccination effort, primarily focused on reducing NPP, may constitute a logical starting place. Sensitivity analyses revealed that a pandemic influenza season or change in size of the US elderly population could increase these costs dramatically.

Modelling the return on investment of preventively vaccinating healthcare workers against pertussis.

BACKGROUND: Healthcare workers (HCWs) are at particular risk of acquiring pertussis and transmitting the infection to high-risk susceptible patients and colleagues. In this paper, the return on investment (ROI) of preventively vaccinating HCWs against pertussis to prevent nosocomial pertussis outbreaks is estimated using a hospital ward perspective, presuming an outbreak occurs once in 10 years. METHODS: Data on the pertussis outbreak on the neonatology ward in 2004 in the Academic Medical Center Amsterdam (The Netherlands) was used to calculate control costs and other outbreak related costs. The study population was: neonatology ward staff members (n = 133), parents (n = 40), neonates (n = 20), and newborns transferred to other hospitals (n = 23). ROI is presented as the amount of Euros saved in averting outbreaks by investing one Euro in preventively vaccinating HCWs. Sensitivity analysis was performed to study the robustness of the ROI. Results are presented at 2012 price level. RESULTS: Total nosocomial pertussis outbreak costs were €48,682. Direct control costs (i.e. antibiotic therapy, laboratory investigation and outbreak management control) were €11,464. Other outbreak related costs (i.e. sick leave of HCWs; restrictions on the neonatology ward, savings due to reduced working force required) accounted for €37,218. Vaccination costs were estimated at €12,208. The ROI of preventively vaccinating HCWs against pertussis was 1:4, meaning 4 Euros could be saved by every Euro invested in vaccinating HCWs to avert outbreaks. ROI was sensitive to a lower vaccine price, considering direct control costs only, average length of stay of neonates on the neonatology ward, length of patient uptake restrictions, assuming no reduced work force due to ward closer and presuming more than one outbreak to occur in 10 years' time. CONCLUSION: From a hospital ward perspective, preventive vaccination of HCWs against pertussis to prevent nosocomial pertussis outbreaks results in a positive ROI, presuming an outbreak occurs once in 10 years.

Cost-benefit of the introduction of new strategies for vaccination against pertussis in Spain: cocooning and pregnant vaccination strategies.

BACKGROUND: Pertussis remains a public health problem in countries with high vaccination coverage. Classic vaccination approaches have failed to effectively control the infection. The incidence of pertussis hospitalizations in infants is high, especially in those younger than 3 months who are in high risk of a severe disease and death. Additional strategies are recommended for short-term protection of this vulnerable population. In this study, we estimated the impact of 2 strategies for pertussis prevention in infants younger than 1 year of age-a cocoon vaccination strategy and the vaccination of pregnant women (VPW)-and the cost-benefit of these approaches relative to the current vaccination policy in Spain. METHODS: A cost-benefit analysis was conducted from the perspective of the publically-funded Spanish healthcare system, based on the yearly number of hospitalizations during the period of 2009 to 2011. We calculated the absolute risk reduction, the number of parents that would need to be vaccinated to prevent 1 hospitalization or death in infants <1 year, and the net benefit-to-cost ratio of each strategy. RESULTS: From 2009 to 2011, the incidence of pertussis in Spain was 153.44 hospitalizations per 100,000 infants <1 year. The absolute risk reduction for hospitalization would be 42.1/100,000 with cocooning and 75.2/100,000 with VPW. The number of parents needed to vaccinate with the cocoon strategy to prevent 1 pertussis hospitalization would be 4752 and to prevent 1 death, more than 900,000. With VPW, 1331 pregnant women would have to be vaccinated to prevent 1 hospitalization and 200,000 to prevent 1 death. The benefit-to-cost ratio was 0.04 for cocooning and 0.15 for VPW.

Estimation of the serial interval of pertussis in Dutch households.

Increasing incidence has led to the re-appearance of pertussis as a public health problem in developed countries. Pertussis infection is usually mild in vaccinated children and adults, but it can be fatal in infants who are too young for effective vaccination (≤3 months). Tailoring of control strategies to prevent infection of the infant hinges on the availability of estimates of key epidemiological quantities. Here we estimate the serial interval of pertussis, i.e., the time between symptoms onset in a case and its infector, using data from a household-based study carried out in the Netherlands in 2007-2009. We use statistical methodology to tie infected persons to probable infector persons, and obtain statistically supported stratifications of the data by person-type (infant, mother, father, sibling). The analyses show that the mean serial interval is 20 days (95% CI: 16-23 days) when the mother is the infector of the infant, and 28 days (95% CI: 23-33 days) when the infector is the father or a sibling. These time frames offer opportunities for early mitigation of the consequences of infection of an infant once a case has been detected in a household. If preventive measures such as social distancing or antimicrobial treatment are taken promptly they could decrease the probability of infection of the infant.

A cocooning project to protect newborns from pertussis.

The Pertussis Cocooning Project was created through a collaborative effort by a health care organization and a State Department for Public Health to decrease community pertussis rates and protect infants from the deadly effects of pertussis. Free pertussis immunizations are provided to all mothers who give birth at the health care organization and to all infants' family members and caregivers older than 18 years.

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 of targeted vaccination to protect new-borns against pertussis: comparing neonatal, maternal, and cocooning vaccination strategies.

Pertussis (whooping cough) is a severe infectious disease in infants less than 6 months old. Mass vaccination programmes have been unable to halt transmission effectively. Strategies to protect new-borns against infection include vaccination of the neonate or the mother directly after birth (cocooning), or the mother during pregnancy (maternal). Here we investigate the cost-effectiveness of these three strategies in the Netherlands. Costs for health care utilization and productivity losses, as well as impact on quality of life were calculated for a 10-year vaccination programme, assuming that vaccine-induced immunity lasts 5 years. Cocooning was the most attractive option from a cost-effectiveness viewpoint (€89,000/QALY). However, both cocooning and maternal vaccination would reduce the disease burden in infants and mothers vaccinated (about 17-20 QALY/year). Specifically, with a persistent epidemic as seen in 2012, there is need for reconsidering the vaccination schedules against pertussis in order to increase protection of the vulnerable new-borns.

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.

Parent "cocoon" immunization to prevent pertussis-related hospitalization in infants: the case of Piemonte in Italy.

Pertussis incidence in Piemonte (Italy) is now at the lowest level ever reached (0.85 per 100,000 in 2010) but the disease is still endemic in infants (54 per 100,000 in 2005-2010). Parental "cocoon" immunization has been proposed in some countries (i.e. United States, France) as a measure to protect newborns from serious pertussis outcomes. We assessed the number needed to vaccinate (NNV) to prevent hospital admissions in infants (<12 months) and the potential cost-effectiveness of this strategy in Piemonte. The NNV for parental immunization was at least 5000 to prevent one infant hospitalization in the latest epidemic cycle (2005-2010) at the cost of >€100,000. The "cocoon" programme leads to net costs from a National Health Service (NHS) perspective (ROI<1). In contexts of low incidence and without reliable data on a high parent-attributable infant risk, the parental "cocoon" programme is poorly efficient and very resource intensive in preventing pertussis in infants.

Dynamic models for health economic assessments of pertussis vaccines: what goes around comes around....

Despite childhood vaccination programs, pertussis remains endemic. To reduce the burden of pertussis, various extended pertussis vaccination strategies have been suggested. The aim of this article is to evaluate dynamic models used to assess the cost-effectiveness of vaccination. In total, 16 studies using a dynamic model were included, of which four also studied the cost-effectiveness of extended pertussis vaccination strategies. Generally, adolescent vaccination was found to be cost effective, but not highly effective in protecting infants too young to be vaccinated. The models also predicted that owing to age shifts, reduced pertussis disease in adolescents and young adults comes with an increase in later stages of life. This underpins the use of dynamic transmission models for interventions directed against pertussis. In future, dynamic transmission models for pertussis should be used widely to further enhance understanding of pertussis epidemiology and of extended pertussis vaccination programs that are currently considered in various countries.