title: Effectiveness of MF59™ adjuvanted influenza A(H1N1)pdm09 vaccine in risk groups in the Netherlands.
abstract: BACKGROUND
  The aim of the present study was to estimate the effectiveness of the MF59™-adjuvanted influenza A(H1N1)pdm09 vaccine against medically attended influenza-like illness and RT-PCR confirmed influenza in the at-risk population and persons over 60 in the Netherlands.
  
  
  METHODS
  We conducted a retrospective cohort study in a Dutch based GP medical record database between 30 November 2009 and 1 March 2010 to estimate the vaccine effectiveness against influenza-like illness. Within the cohort we nested a test negative case-control study to estimate the effectiveness against laboratory confirmed influenza.
  
  
  RESULTS
  The crude effectiveness in preventing diagnosed or possible influenza-like illness was 17.3% (95%CI: -8.5%-36.9%). Of the measured covariates, age, the severity of disease and health seeking behaviour through devised proxies confounded the association between vaccination and influenza-like illness. The adjusted vaccine effectiveness was 20.8% (95%CI: -5.4%, 40.5%) and varied significantly by age, being highest in adults up to 50 years (59%, 95%CI: 23%, 78%), and non-detectable in adults over 50 years. The number of cases in the nested case control study was too limited to validly estimate the VE against confirmed influenza.
  
  
  CONCLUSIONS
  With our study we demonstrated that the approach of combining a cohort study in a primary health care database with field sampling is a feasible and useful option to monitor VE of influenza vaccines in the future.
authors: Erasmus Medical Center, Rotterdam, The Netherlands ; Medicines Evaluation Board, Utrecht, The Netherlands. e.wijnans@erasmusmc.nl
authors: Leonoor
authors: L
authors: Wijnans
authors: Jeanne
authors: J
authors: Dieleman
authors: Bettie
authors: B
authors: Voordouw
authors: Miriam
authors: M
authors: Sturkenboom
mesh_terms: D000276:Adjuvants, Immunologic; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011136:Polysorbates; D012189:Retrospective Studies; D013185:Squalene; D014611:Vaccination; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D007252:Influenza Vaccines; C089950:MF59 oil emulsion; D011136:Polysorbates; D013185:Squalene
references: Vaccine. 2011 Aug 11;29(35):5919-24
references: 21723358
references: Euro Surveill. 2011 Jan 13;16(2):
references: 21251487
references: PLoS One. 2011 May 10;6(5):e19621
references: 21573005
references: J Infect Dis. 2011 Jan 1;203(1):32-9
references: 21148494
references: Methods Inf Med. 1999 Dec;38(4-5):339-44
references: 10805025
references: N Engl J Med. 2009 Nov 12;361(20):1945-52
references: 19745214
references: BMC Public Health. 2011 Nov 30;11:899
references: 22129083
references: BMC Infect Dis. 2011 Jul 18;11:196
references: 21767348
references: Nature. 2006 Jul 27;442(7101):448-52
references: 16642006
references: Vaccine. 2011 Feb 4;29(7):1395-8
references: 21199701
references: Vaccine. 2009 Aug 13;27(37):5043-53
references: 19559118
references: PLoS One. 2011;6(7):e19932
references: 21789163
references: Clin Infect Dis. 2011 May;52(10):1203-11
references: 21507917
references: PLoS Med. 2011 Jan;8(1):e1000388
references: 21379316
references: Vaccine. 2010 Nov 3;28(47):7460-7
references: 20875486
references: BMJ. 2011 Feb 03;342:c7297
references: 21292718
references: Arch Intern Med. 2006 Oct 9;166(18):1980-5
references: 17030831
references: Health Technol Assess. 2010 Jul;14(34):313-46
references: 20630126
references: Ann Intern Med. 1993 Nov 15;119(10):1036-41
references: 8214981
references: Euro Surveill. 2010 May 06;15(18):
references: 20460094
references: Euro Surveill. 2009 Oct 15;14(41):19361
references: 19883538