Effectiveness of the trivalent influenza vaccine in Navarre, Spain, 2010–2011: a population-based test-negative case–control studyReport as inadecuate

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BMC Public Health

, 13:191

Health behavior, health promotion and society


BackgroundSome studies have evaluated vaccine effectiveness in preventing outpatient influenza while others have analysed its effectiveness in preventing hospitalizations. This study evaluates the effectiveness of the trivalent influenza vaccine in preventing outpatient illness and hospitalizations from laboratory-confirmed influenza in the 2010–2011 season.

MethodsWe conducted a nested case–control study in the population covered by the general practitioner sentinel network for influenza surveillance in Navarre, Spain. Patients with influenza-like illness in hospitals and primary health care were swabbed for influenza testing. Influenza vaccination status and other covariates were obtained from health care databases. Using logistic regression, the vaccination status of laboratory-confirmed influenza cases was compared with that of test-negative controls, adjusting for age, sex, comorbidity, outpatient visits in the previous 12 months, health care setting, time between symptom onset and swabbing, period and AH1N1pdm09 vaccination. Effectiveness was calculated as 1-odds ratiox100.

ResultsThe 303 confirmed influenza cases 88% for AH1N1pdm09 influenza were compared with the 286 influenza test-negative controls. The percentage of persons vaccinated against influenza was 4.3% and 15.7%, respectively p<0.001. The adjusted estimate of effectiveness was 67% 95% CI: 24%, 86% for all patients and 64% 95% CI: 8%, 86% in those with an indication for vaccination persons age 60 or older or with major chronic conditions. Having received both the 2010–2011 seasonal influenza vaccine and the 2009–2010 pandemic influenza vaccine provided 87% protection 95% CI: 30%, 98% as compared to those not vaccinated.

ConclusionThe 2010–2011 seasonal influenza vaccine had a moderate protective effect in preventing laboratory-confirmed influenza.

KeywordsInfluenza A virus H1N1 subtype Influenza vaccines Case–control studies Spain AbbreviationsILIInfluenza-like illness

CIConfidence interval

OROdds ratio.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2458-13-191 contains supplementary material, which is available to authorized users.

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Source: https://link.springer.com/


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