J M Bos

University of Groningen, Groningen, Groningen, Netherlands

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Publications (40)96.91 Total impact

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    J. Bos, M. Postma
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    ABSTRACT: Infectious diseases are an important cause of mortality and morbidity, causing approximately 27% of the total disease burden in DALY. A large part of DALY lost due to infectious diseases could be prevented by improving existing vaccination programs for the population. Diseases such as childhood cluster diseases, hepatitis A and B, respiratory infections caused by influenza, pneumococcal and meningococcal infections, and Hemophilus influenzae type B, are for a large part preventable by current vaccines. The implementation of new vaccine programs or/and strategies is often a costly process with long term consequences. Vaccination programs often concern a large part of the population, and have a large budget impact. Once a vaccination program has started, it is (due to equity reasons) extremely difficult to cease the program. To gain a better understanding of the potential impact on health benefits and costs of a vaccine intervention, health-economic evaluations are frequently used, which estimate the future impact on health gains and costs. Health-economic evaluations are mostly presented as one of the following four types of analysis: cost-minimization, cost-benefit, cost-effectiveness and cost-utility analysis. In this chapter, we provide an overview of the main techniques and challenges associated with health economic evaluations of vaccination programs, such as the choice of the model. Additionally, an overview of health economic evaluations that have been performed on currently implemented vaccination strategies is presented. From our analysis it follows that vaccine programs, and especially those against childhood cluster diseases, and vaccination of elderly against influenza are amongst the world’s most cost-effective interventions.
    12/2009: pages 1335-1352;
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    ABSTRACT: This study aims to measure the direct and indirect costs of HIV/AIDS care and quality of life (QoL) of HIV-infected patients in Northern Italy. We conducted a prospective cohort study over 12 months, enrolling a sample of 121 patients with HIV infection from two cities in Northern Italy. Patients were surveyed at baseline and were followed-up at 6 and 12 months. To assess the relationship between costs and stage of disease, patients were categorized into three groups at baseline: "No HAART" (asymptomatic and never before on highly active antiretroviral therapy (HAART)), "Stable HAART" (HAART with mild HIV infection and no prior opportunistic infections) and "HAART failure" (primary HAART regimen was altered because of severe side effects or immunological failure). Direct medical costs were based on utilization of (day) hospital admissions, diagnostic procedures, laboratory tests, clinic visits, consultations and antiretroviral drug use. Indirect costs included production losses due to absence from work, reduced productivity at work and reduced unpaid labour participation. QoL was assessed by visual analogue scale. Parametric regression was used to estimate the expected value and the standard deviation of annual costs per patient. The expected value of total annual costs was 1818 euros and 9820 euros and 12,332 euros, for groups "No HAART", "Stable HAART" and "HAART failure" respectively. We estimated annual expected earnings as 14,994 euros and 10,811 euros and 9820 euros for the same respective groups. The expected value of QoL on a scale of 0-1 in these same patient groups was 0.80, 0.78 and 0.64. We conclude that indirect costs contribute substantially to total costs and are comparable in magnitude to the direct costs excluding antiretroviral drugs. The costs of inpatient care in our cohort were almost negligible compared to total costs. Despite being in treatment, many patients were still gainfully employed and generated substantial expected annual earnings.
    AIDS Care 05/2008; 20(4):449-55. · 1.60 Impact Factor
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    ABSTRACT: Health-economic modelling is useful for assessing the clinical requirements and impact of new vaccines. In this study, we estimate the impact of potential vaccination for respiratory syncytial virus (RSV) of infants in the Netherlands. A decision analysis model was employed using seasonal data from a cohort of children (1996-1997 through 1999-2000) to assess hospitalisation, costs and impact of vaccination. Yearly, an estimated 3670 infants are hospitalised with RSV-infection in the Netherlands, vaccination protecting infants from 3 months of life onwards could prevent approximately 1000-3000 hospitalisations, depending on the effectiveness of the potential vaccine. Additionally, vaccination could prevent a major share of RSV-related costs. Comparison of the calculated break-even prices with the average price of recently introduced vaccines indicates that pricing for a potential RSV-vaccine most likely allows for only a single dose vaccination or several doses at a relatively low price per dose in order to achieve cost savings. However, if evidence on relevant RSV-related mortality would become available, higher pricing would be justified, while still remaining below accepted thresholds for cost-effectiveness.
    Vaccine 10/2007; 25(39-40):6922-9. · 3.49 Impact Factor
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    ABSTRACT: We have developed a web-based user-interface (web interface) to enhance the usefulness of health-economic evaluations to support decision making (http://pcv.healtheconomics.nl). It allows the user to interact with a health-economic model to evaluate predefined and customized scenarios and perform sensitivity analysis. To explore its usefulness, it was applied to an evaluation of cost-effectiveness of nation-wide infant vaccination with the 7-valent pneumococcal conjugate vaccine (PCV7), that was used to support a policy decision on the inclusion of PCV7 in the national vaccination program (NVP) of the Netherlands. We used a decision-tree analytic model to project the impact of infant vaccination with four doses of PCV7 on an annual cohort of infants born in the Netherlands. The base-case analysis includes the beneficial effects on unvaccinated individuals (herd protection). Additional scenarios varying the number of doses, discount rate for effects and the number of serotypes in the vaccine were evaluated and can be analysed on the web. Our model projects a base-case incremental cost-effectiveness ratio (iCER) of euro14,000 (95% uncertainty interval (UI): 9,800-20,200) per quality adjusted life year (QALY) or euro15,600 (95% UI: 11,100-23,900) per life year gained (LYG).
    Vaccine 06/2007; 25(18):3669-78. · 3.49 Impact Factor
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    ABSTRACT: This study compares the costs and effects of a regimen with ritonavir-boosted tipranavir (TPV/r) to a physician-selected genotypically-defined standard-of-care comparator protease inhibitor regimen boosted with ritonavir (CPI/r) in HIV infected patients that were previously exposed to antiretroviral therapy in the Netherlands. We compared the projected lifetime costs and effects of two theoretical groups of 1000 patients, one receiving a standard of care regimen with TPV/r as a component and the other receiving a standard of care regimen with CPI/r. A 3-stage Markov model was formulated to represent three different consecutive HAART regimens. The model uses 12 health states based on viral load and CD4+ count to simulate disease progression. The transition probabilities for the Markov model were derived from a United States cohort of treatment experienced HIV patients. Furthermore, the study design was based on 48-week data from the RESIST-2 clinical trial and local Dutch costing data. Cost and health effects were discounted at 4% and 1.5% respectively according to the Dutch guideline. The analysis was conducted from the Dutch healthcare perspective using 2006 unit cost prices. Our model projects an accumulated discounted cost to the Dutch healthcare system per patient receiving the TPV/r regimen of euro167,200 compared to euro145,400 for the CPI/r regimen. This results in an incremental cost of euro21,800 per patient. The accumulated discounted effect is 7.43 life years or 6.31 quality adjusted life years (QALYs) per patient receiving TPV/r, compared to 6.91 life years or 5.80 QALYs per patient receiving CPI/r. This translates into an incremental effect of TPV/r over CPI/r of 0.52 life years gained (LYG) or 0.51 QALYs gained. The corresponding incremental cost effectiveness ratios (iCERs) are euro41,600 per LYG and euro42,500 per QALY. We estimated the iCER for TPV/r compared to CPI/r at approximately euro40,000 in treatment experienced HIV-1 infected patients in the Netherlands. This ratio may well be in range of what is acceptable and warrants reimbursement for new drug treatments in the Netherlands, in particular in therapeutic areas as end-stage oncology and HIV and other last-resort health-care interventions.
    Cost Effectiveness and Resource Allocation 02/2007; 5:15. · 0.87 Impact Factor
  • PharmacoEconomics 12/2006; 24(12). · 2.86 Impact Factor
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    ABSTRACT: Streptococcus pneumoniae and Neisseria meningitidis group B are among the main causes of invasive bacterial meningitis infections in infants. Worldwide, these diseases lead to significant mortality, morbidity and costs. The societal impact is especially severe since the majority of cases occur in very young infants. A combination vaccine consisting of 9-valent conjugated pneumococcal and meningococcal B components is currently being developed. The aim of this study was to estimate the potential impact and cost effectiveness from the societal perspective of vaccinating infants in The Netherlands with this combination pneumococcal and meningococcal B vaccine versus no vaccination. A Markov cycle model was developed using epidemiological and healthcare resource use data from 1996 to 2001. This model was used to project the annual costs, benefits and health gains associated with vaccinating all newborns. The base year for the costing was 2003 and all costs and health effects were discounted at 4%. The results of the analysis are expressed in costs per QALY and both probabilistic and univariate sensitivity analyses were used to identify the robustness of the results. Annually, an average of 755 cases of invasive pneumococcal and meningococcal B infection occurred in infants aged 0-10 years in The Netherlands. Introduction of the combination vaccine would prevent 201 cases of meningococcal B meningitis and 165 cases of invasive pneumococcal disease per year. Additionally, 3410 cases of pneumococcal pneumonia and 46,350 cases of otitis media would be prevented. Vaccination would save 35 lives per year and prevent 71 cases of severe sequelae. This translates into 860 life-years gained, or 1128 QALYs gained. Alongside these health gains, vaccination would prevent euro 17,681,370 of direct medical and indirect costs attributable to meningococcal and pneumococcal infections in The Netherlands. Depending on vaccine price, cost effectiveness varied from euro 3160 (vaccine price per dose euro 20) to euro 32,170 (vaccine price euro 60 per dose) per QALY. Base-case cost effectiveness (vaccine price euro 40) was euro 17,700 per QALY. The model was most sensitive to changes in incidence, vaccine price and duration of protective efficacy. Our results suggest that the introduction of a combination meningococcal B and pneumococcal vaccine into the Dutch infant vaccination programme is potentially cost effective compared with no vaccination.
    PharmacoEconomics 02/2006; 24(2):141-53. · 2.86 Impact Factor
  • PharmacoEconomics 02/2006; 24(12):1275-1276. · 2.86 Impact Factor
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    ABSTRACT: Background: Streptococcus pneumoniae and Neisseria meningitidis group B are among the main causes of invasive bacterial meningitis infections in infants. Worldwide, these diseases lead to significant mortality, morbidity and costs. The societal impact is especially severe since the majority of cases occur in very young infants. A combination vaccine consisting of 9-valent conjugated pneumococcal and meningococcal B components is currently being developed. The aim of this study was to estimate the potential impact and cost effectiveness from the societal perspective of vaccinating infants in The Netherlands with this combination pneumococcal and meningococcal B vaccine versus no vaccination. Methods: A Markov cycle model was developed using epidemiological and healthcare resource use data from 1996 to 2001. This model was used to project the annual costs, benefits and health gains associated with vaccinating all newborns. The base year for the costing was 2003 and all costs and health effects were discounted at 4%. The results of the analysis are expressed in costs per QALY and both probabilistic and univariate sensitivity analyses were used to identify the robustness of the results. Results: Annually, an average of 755 cases of invasive pneumococcal and meningococcal B infection occurred in infants aged 0-10 years in The Netherlands. Introduction of the combination vaccine would prevent 201 cases of meningococcal B meningitis and 165 cases of invasive pneumococcal disease per year. Additionally, 3410 cases of pneumococcal pneumonia and 46_350 cases of otitis media would be prevented. Vaccination would save 35 lives per year and prevent 71 cases of severe sequelae. This translates into 860 life-years gained, or 1128 QALYs gained. Alongside these health gains, vaccination would prevent _17_681_370 of direct medical and indirect costs attributable to meningococcal and pneumococcal infections in The Netherlands. Depending on vaccine price, cost effectiveness varied from _3160 (vaccine price per dose _20) to _32_170 (vaccine price _60 per dose) per QALY. Base-case cost effectiveness (vaccine price _40) was _17_700 per QALY. The model was most sensitive to changes in incidence, vaccine price and duration of protective efficacy. Conclusion: Our results suggest that the introduction of a combination meningococcal B and pneumococcal vaccine into the Dutch infant vaccination programme is potentially cost effective compared with no vaccination.
    PharmacoEconomics 01/2006; 24(2):141-153. · 2.86 Impact Factor
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    ABSTRACT: This study examines the adherence of Dutch pharmacoeconomic studies to the national guidelines of conducting a pharmacoeconomic evaluation.Methods: Dutch guidelines for pharmacoeconomic research were issued in 1999. All Dutch pharmacoeconomic studies that were published in English during 2000-2002 were selected for our review. Two reviewers examined each study for relevance and compared each study with the nine methodological guidelines selected. It was found that 29 studies satisfied the inclusion criteria. The societal perspective was taken in 13 out of the 29 studies (45%), an adequate time period of analysis was chosen in 21 (72%), effectiveness was explicitly differentiated from efficacy in 17 (59%), an incremental analysis was performed in 23 (79%), costs, benefits and health gains were discounted in 24 (83%), effectiveness was expressed in LYGs or QALYs in 16 (55%), reference prices were used in 8 (28%), subgroup analysis was presented in 13 (45%) and sensitivity analysis was included in 26 (90%). In this review we found that the adherence of studies to some of the Dutch guidelines for pharmacoeconomic studies is fair. However, major improvements are required with respect to the adoption of the societal perspective, presentation of adequate subgroup analyses and application of reference prices.
    International Journal of Clinical Pharmacy 11/2005; 27(5):364-70. · 1.27 Impact Factor
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    ABSTRACT: Most national guidelines for pharmacoeconomic research prescribe discounting, mostly of money and health against the same rate. There is much debate on whether this is adequate. Two theoretical arguments, the consistency argument of Weinstein and Stason, and the paralyzing paradox of Keeler and Cretin, are mostly responsible for the current standards. However, more recently, several authors have indicated that the basis to claim the necessity of using similar discount rates is rather weak, both practically and theoretically. In terms of finding a new theoretical basis on which to base discount rates for money and, in particular, health, Van Hout has made an important suggestion arguing that the discount rate for health could be based on the expected growth in life expectancy and the diminishing marginal utility related to such additional health. Similarly, Gravelle and Smith argue that if the value of health grows over time, discount rates that are used for costs cannot directly be applied to effects, but should be adjusted downwards.
    Expert Review of Pharmacoeconomics & Outcomes Research 02/2005; 5(1):59-63. · 1.67 Impact Factor
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    ABSTRACT: In order to increase price competition, government regulations focus on controlling drug costs. Drug costs after patent expiry are an area of particular interest because the substitution of branded medication with generics represents an opportunity for lowering drug costs. However, drug costs may not decrease after patent expiry, because of a lack of price competition and different national pricing systems. The aim of this study was to investigate the trends in the use of generics after patent expiry for enalapril, fluoxetine and ranitidine and the subsequent changes, if any, in the costs of these medications. A drug-utilisation study was performed using data from a large sample of Dutch pharmacies. Both volumes (measured as defined daily doses [DDD] per 1000 population) as well as drug costs (calculated per DDD) prior to and after patent expiry were calculated. Costs per DDD were compared using trend-line analysis. In addition, the relative market shares of the different trade channels (branded, parallel imported and generic) were compared before and after patent expiry. The costs per DDD decreased for all three drugs and, as expected, these costs decrease more rapidly after patent expiry. Significant differences in the trend lines were found for enalapril and fluoxetine. Despite relatively high reimbursement prices for generics in the Netherlands, this example from the Dutch pharmaceutical market demonstrates the benefit of generic substitution for containing pharmaceutical costs, which contrasts with concerns raised by the Dutch government.
    Applied Health Economics and Health Policy 02/2005; 4(3):191-6.
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    ABSTRACT: Currently, much debate still surrounds the discounting of health effects. Most general consensus statements have argued for the same discount rate for health and money; however, this practice has been questioned by several authors. The choice of discount rate can have varying effects on interventions, depending on the disease area. In this paper, we review two major current controversies around discounting: the use of similar or differential discount rates for health and money; and the validity of the underlying discounting model (time preference, constant discounting and the use of aggregated utilities for health effects). Various arguments justify a different rate of discounting for health effects than for money. Empirical evidence questions the validity of the constant discounting model, pointing out that time preference is not constant and should not be applied as such. Also, the validity of the aggregated utility model for health might be questioned, implying that a life cannot simply be cut into life years as single entities that are discounted back to the net present value. Such debates have led to varying methodologies being employed in economic evaluations, causing difficulties in their interpretation. Although there is sufficient evidence to question the use of similar discount rates for health and money, currently there is not enough information on the nature of the different processes that constitute discounting to reach a solid conclusion on the use of a different method. The lack of consensus on one of the most important topics in pharmacoeconomics makes the case for a more restricted use of cost-effectiveness or cost-utility ratios than as the most important singular outcome of pharmacoeconomic studies. Instead, results should be presented in a non-aggregated manner that enables policy makers to value health gains according to timing and to which subpopulation they are accrued in.
    PharmacoEconomics 02/2005; 23(7):639-49. · 2.86 Impact Factor
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    ABSTRACT: The cost-effectiveness of one time vaccination of all persons aged 14 months to 18 years (catch-up programme) and of routine childhood immunisation at either ages 2 + 3 + 4 months, 5 + 6 months, or 14 months with a meningococcal C conjugate vaccine was estimated for The Netherlands, from a societal and a health care payer perspective. A decision analysis cohort model was employed (time horizon 77 years), direct and indirect costs (friction cost method) were considered and future costs and effects were discounted at 4%. The results showed that all vaccination options yield a substantial health gain and that the catch-up programme and routine vaccination at 14 months render favourable cost-effectiveness ratios: between about 13,200 and 17,700 per life year gained for the catch-up programme and between about 2200 and 2400 per life year gained for routine childhood vaccination at 14 months, depending on the perspective. In comparison to vaccination at 14 months, routine childhood vaccination during the first year of life is much less cost-effective: each additional life year gained costs approximately 147,000 (2 + 3 + 4 months) or 102,000 (5 + 6 months), from both perspectives. Additionally, inclusion of the likely herd immunity effect of the catch-up programme increases these incremental cost-effectiveness ratios. These results played a major role in the decision to add meningococcal C vaccination to the routine childhood immunisation schedule at 14 months and to implement a catch-up vaccination programme in The Netherlands in 2002.
    Vaccine 01/2005; 23(4):470-9. · 3.49 Impact Factor
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    ABSTRACT: Background: In order to increase price competition, government regulations focus on controlling drug costs. Drug costs after patent expiry are an area of particular interest because the substitution of branded medication with generics represents an opportunity for lowering drug costs. However, drug costs may not decrease after patent expiry, because of a lack of price competition and different national pricing systems.Aim: The aim of this study was to investigate the trends in the use of generics after patent expiry for enalapril, fluoxetine and ranitidine and the subsequent changes, if any, in the costs of these medications.Methods: A drug-utilisation study was performed using data from a large sample of Dutch pharmacies. Both volumes (measured as defined daily doses [DDD] per 1000 population) as well as drug costs (calculated per DDD) prior to and after patent expiry were calculated. Costs per DDD were compared using trend-line analysis. In addition, the relative market shares of the different trade channels (branded, parallel imported and generic) were compared before and after patent expiry.Results: The costs per DDD decreased for all three drugs and, as expected, these costs decrease more rapidly after patent expiry. Significant differences in the trend lines were found for enalapril and fluoxetine.Conclusions: Despite relatively high reimbursement prices for generics in the Netherlands, this example from the Dutch pharmaceutical market demonstrates the benefit of generic substitution for containing pharmaceutical costs, which contrasts with concerns raised by the Dutch government.
    Applied Health Economics and Health Policy 12/2004; 4(3):191-196.
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    ABSTRACT: Estimate cost-effectiveness of vaccination against hepatitis A virus (HAV) for children of ethnic minorities in Amsterdam. Pharmaco-economic analysis is relevant for motivating reimbursement of vaccination costs in the framework of a programmatic approach to vaccination of ethnic minorities. Pharmaco-economic modeling. In cost-effectiveness analysis, costs, benefits and health gains were estimated for a large-scale HAV-vaccination for children of Turkish and Maroccan origin. Analysis was performed from the societal perspective, as recommended in the Dutch guidelines for pharmaco-economic research. This implies that indirect costs of production losses are included in the analysis. Cost-effectiveness was expressed in net costs per adult HAV-infection averted in incremental and aggregate analysis. Incremental analysis compares targeted vaccination with the current limited-scale HAV-vaccination that exists, whereas aggregate analysis compares targeted vaccination with the sheer absence of vaccination. Net aggregate costs of targeted HAV-vaccination for Turkish and Maroccan children in Amsterdam amounts to 61.000. Cost-effectiveness was estimated, in aggregate and incremental analysis, at 13.500 and 11.100 respectively per adult HAV-infection averted. Uni- and multivariate sensitivity analyses show that major impact on cost-effectiveness may be expected from reductions in the vaccine price through economies of scale. Probabilistic sensitivity analysis indicates possible large fluctuations in cost-effectiveness from 1 year to another, related to varying incidence of disease. HAV-vaccination for children from ethnic minorities in Amsterdam is not cost saving, but may have a favourable cost-effectiveness. Such a vaccination program fits into the recent Dutch policy of specific vaccinations directed at groups of ethnic minorities, such as for hepatitis B.
    Vaccine 06/2004; 22(15-16):1862-7. · 3.49 Impact Factor
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    Jasper M Bos, Maarten J Postma
    Expert Review of Pharmacoeconomics & Outcomes Research 06/2004; 4(3):247-50. · 1.67 Impact Factor
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    The European Journal of Health Economics 03/2004; 5(1):54-7. · 2.10 Impact Factor
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    ABSTRACT: In cost-effectiveness analysis, the valuing of costs and health effects over time remains a controversial issue. The debate mostly focuses on whether the discount rates for health and money should be equal and which discounting model and time preferences are most appropriate. In this paper we add to the debate by arguing that the assessment of effectiveness of a preventive intervention may influence the choice of the discounting procedure for health. Health effects in cost-effectiveness analysis are commonly expressed in life-years gained, QALYs gained or lives saved. These denominators are only indirect and partial measures of the effects of a preventive intervention. The actual effect of the intervention is a reduction of the risk of mortality and morbidity in a given period of time. This risk reduction will not always coincide with the moment at which the impact on (quality-adjusted) life-years gained is made (i.e. at risk exposure), for example when preventing chronic disease with an asymptomatic stage. In this paper we show that truly acknowledging the origin of health benefits could have implications for the discounting procedure. We present a discounting model that adequately focuses on the reduction of risk. This model recognises the potential interpretation of risk reduction for infection as an economic good to be acquired with associated mortality reductions as later indirect effects. This implies that our suggested discounting model focuses on the moment(s) of risk reduction. A numerical example illustrates our approach. We discuss the associated potential implications for public health policy and discuss how the effects of the intervention can be additionally corrected for societal preferences.
    PharmacoEconomics 02/2004; 22(18):1171-9. · 2.86 Impact Factor
  • Value in Health 01/2004; 7(6):761-761. · 2.19 Impact Factor

Publication Stats

391 Citations
96.91 Total Impact Points

Institutions

  • 2001–2007
    • University of Groningen
      • • PharmacoEpidemiology and PharmacoEconomics (PE²) Unit
      • • Groningen Research Institute of Pharmacy (GRIP)
      Groningen, Groningen, Netherlands
    • National Institute for Public Health and the Environment (RIVM)
      Utrecht, Utrecht, Netherlands
  • 2006
    • Ghent University
      • Department of Public Health
      Gand, Flanders, Belgium
  • 2004–2005
    • Netherlands Vaccine Institute (NVI)
      Utrecht, Utrecht, Netherlands