title: Influenza vaccine effectiveness estimates in Croatia in 2010-2011: a season with predominant circulation of A(H1N1)pdm09 influenza virus.
abstract: This is a retrospective study using the test-negative case-control method to estimate seasonal 2010-2011 influenza vaccine effectiveness (VE) in Croatia. Of patients consulting a physician for influenza-like illness (ILI) and for whom a swab was taken, we compared RT-PCR influenza-positive and RT-PCR influenza-negative patients. We used a structured questionnaire and physicians' records to obtain information on vaccination status and potential confounders. We conducted a complete case analysis using logistic regression to measure adjusted VE overall, against A(H1N1)pdm09 and in age groups. Out of 785 interviewed patients, 495 eligible patients were included in the study, after applying exclusion criteria [217 cases, of which 92·6% were A(H1N1)pdm09 positive, 278 controls]. Crude VE was 31·9% [95% confidence interval (CI) -40·9 to 67·1] and adjusted VE was 20·7% (95% CI -71·4 to 63·3), with higher VE in youngest and oldest age groups. Results from this first VE study in Croatia suggest a low to moderate VE for the 2010-2011 season. Studies year on year are needed with a greater sample size to provide more precise estimates, and also by age group and risk groups for vaccination.
authors.affiliation: Epidemiology Department,Croatian National Institute of Public Health,Zagreb,Croatia.
authors.forename: S
authors.initials: S
authors.lastname: Kurečić Filipović
authors.affiliation: University of Applied Health Studies,Zagreb,Croatia.
authors.forename: I
authors.initials: I
authors.lastname: Gjenero-Margan
authors.affiliation: EpiConcept,Paris,France.
authors.forename: E
authors.initials: E
authors.lastname: Kissling
authors.affiliation: Epidemiology Department,Croatian National Institute of Public Health,Zagreb,Croatia.
authors.forename: B
authors.initials: B
authors.lastname: Kaić
authors.affiliation: Public Health Institute,Brodsko-Posavska County,Slavonski Brod,Croatia.
authors.forename: A
authors.initials: A
authors.lastname: Cvitković
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D017523:Croatia / Q000453:epidemiology; D018563:Disease Notification / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines; D007251:Influenza, Human / Q000175:diagnosis / Q000453:epidemiology / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D012367:RNA, Viral / Q000032:analysis; D012189:Retrospective Studies; D014611:Vaccination / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines; D012367:RNA, Viral
keywords: Influenza; influenza vaccines; vaccination (immunization)