title: Effectiveness of the monovalent influenza A(H1N1)2009 vaccine in Navarre, Spain, 2009-2010: cohort and case-control study.
abstract: We defined a population-based cohort (596,755 subjects) in Navarre, Spain, using electronic records from physicians, to evaluate the effectiveness of the monovalent A(H1N1)2009 vaccine in preventing influenza in the 2009-2010 pandemic season. During the 9-week period of vaccine availability and circulation of the A(H1N1)2009 virus, 4608 cases of medically attended influenza-like illness (MA-ILI) were registered (46 per 1000 person-years). After adjustment for sociodemographic covariables, outpatient visits and major chronic conditions, vaccination was associated with a 32% (95% CI: 8-50%) reduction in the overall incidence of MA-ILI. In a test negative case-control analysis nested in the cohort, swabs from 633 patients were included, and 123 were confirmed for A(H1N1)2009 influenza. No confirmed case had received A(H1N1)2009 vaccine versus 9.6% of controls (p<0.001). The vaccine effectiveness in preventing laboratory-confirmed influenza was 89% (95% CI: 36-100%) after adjusting for age, health care setting, major chronic conditions and period. Pandemic vaccine was effective in preventing MA-ILI and confirmed cases of influenza A(H1N1)2009 in the 2009-2010 season.
authors: Instituto de Salud Pública de Navarra, Pamplona, Spain. jcastilc@navarra.es
authors: Jesús
authors: J
authors: Castilla
authors: Julio
authors: J
authors: Morán
authors: Víctor
authors: V
authors: Martínez-Artola
authors: Mirian
authors: M
authors: Fernández-Alonso
authors: Marcela
authors: M
authors: Guevara
authors: Manuel García
authors: MG
authors: Cenoz
authors: Gabriel
authors: G
authors: Reina
authors: Nerea
authors: N
authors: Alvarez
authors: Maite
authors: M
authors: Arriazu
authors: Fernando
authors: F
authors: Elía
authors: Esther
authors: E
authors: Salcedo
authors: Aurelio
authors: A
authors: Barricarte
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D011446:Prospective Studies; D012621:Seasons; D013030:Spain / Q000453:epidemiology; D016896:Treatment Outcome; D014611:Vaccination / Q000706:statistics & numerical data; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines