title: Coverage of the 2011 Q fever vaccination campaign in the Netherlands, using retrospective population-based prevalence estimation of cardiovascular risk-conditions for chronic Q fever.
abstract: BACKGROUND
  In 2011, a unique Q fever vaccination campaign targeted people at risk for chronic Q fever in the southeast of the Netherlands. General practitioners referred patients with defined cardiovascular risk-conditions (age >15 years). Prevalence rates of those risk-conditions were lacking, standing in the way of adequate planning and coverage estimation. We aimed to obtain prevalence rates retrospectively in order to estimate coverage of the Q fever vaccination campaign.
  
  
  METHODS
  With broad search terms for these predefined risk-conditions, we extracted patient-records from a large longitudinal general-practice research-database in the Netherlands (IPCI-database). After validation of these records, obtained prevalence rates (stratified for age and sex) extrapolated to the Q fever high-incidence area population, gave an approximation of the size of the targeted patient-group. Coverage calculation addressed people actually screened by a pre-vaccination Q fever skin test and serology (coverage) and patients referred by their general practitioners (adjusted-coverage) in the 2011 campaign.
  
  
  RESULTS
  Our prevalence estimate of any risk-condition was 3.1% (lower-upper limits 2.9-3.3%). For heart valve defects, aorta aneurysm/prosthesis, congenital anomalies and endocarditis, prevalence was 2.4%, 0.6%, 0.4% and 0.1%, respectively. Estimated number of eligible people in the Q fever high-incidence area was 11,724 (10,965-12,532). With 1330 people screened for vaccination, coverage of the vaccination campaign was 11%. For referred people, the adjusted coverage was 18%. Coverage was lowest among the very-old and highest for people aged 50-70 years.
  
  
  CONCLUSIONS
  The estimated coverage of the vaccination campaign was limited. This should be interpreted in the light of the complexity of this target-group with much co-morbidity, and of the vaccine that required invasive pre-vaccination screening. Calculation of prevalence rates of risk-conditions based on the IPCI-database was feasible. This procedure proved an efficient tool for future use, when prevalence estimates for policy, implementation or surveillance of subgroup-vaccination or other health-care interventions are needed.
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and Environment, Bilthoven, the Netherlands.
authors.forename: Patricia E
authors.initials: PE
authors.lastname: Vermeer-de Bondt
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Teske
authors.initials: T
authors.lastname: Schoffelen
authors.affiliation: Department of Medical Informatics, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Vanrolleghem
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and Environment, Bilthoven, the Netherlands.
authors.forename: Leslie D
authors.initials: LD
authors.lastname: Isken
authors.affiliation: Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands.
authors.forename: Marcel
authors.initials: M
authors.lastname: van Deuren
authors.affiliation: Department of Medical Informatics, Erasmus University Medical Center, Rotterdam, the Netherlands.
authors.forename: Miriam C J M
authors.initials: MC
authors.lastname: Sturkenboom
authors.affiliation: Centre for Infectious Disease Control, National Institute for Public Health and Environment, Bilthoven, the Netherlands.
authors.forename: Aura
authors.initials: A
authors.lastname: Timen
mesh_terms: D000328:Adult; D016208:Databases, Factual; D005260:Female; D005843:Geography; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011159:Population Surveillance; D015995:Prevalence; D011778:Q Fever / Q000453:epidemiology* / Q000517:prevention & control*; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D014611:Vaccination; D055815:Young Adult