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Influenza vaccine effectiveness in preventing outpatient, inpatient, and severe cases of laboratory-confirmed influenza.

Abstract

BACKGROUND

In most seasons, the influenza vaccine is effective in preventing influenza, but it is not clear whether it is equally effective in preventing mild and severe cases. We designed a case-control study to compare the effectiveness of the influenza vaccine in preventing outpatient, inpatient, and severe or fatal cases of laboratory-confirmed influenza.

METHODS

Hospitalized patients (n = 691) with laboratory-confirmed influenza in the 2010-2011 season recruited in 29 Spanish hospitals were individually matched by age, admission/visit date, and province with an outpatient with laboratory-confirmed influenza and an outpatient control. Severe cases were considered those patients admitted to intensive care units or who died in the hospital (n = 177). We compared the influenza vaccine status of controls and outpatient cases, inpatient cases, and severe cases using conditional logistic regression adjusted for potential confounding factors. Severe and nonsevere inpatient influenza cases were compared using unconditional logistic regression. Vaccine effectiveness was (1 - odds ratio) × 100.

RESULTS

Vaccine effectiveness was 75% (adjusted odds ratio [AOR], 0.25; 95% confidence interval [CI], .16-.39) in preventing influenza outpatient cases, 60% (AOR, 0.40; 95% CI, .25-.63) in preventing influenza-associated hospitalizations, and 89% (AOR, 0.11; 95% CI, .04-.37) in preventing severe cases. In inpatients, influenza vaccination was associated with a lower risk of severe influenza (AOR, 0.42; 95% CI, .22-.80).

CONCLUSIONS

Influenza vaccination prevented influenza cases and hospitalizations and was associated with a better prognosis in inpatients with influenza. The combined effect of these 2 mechanisms would explain the high effectiveness of the vaccine in preventing severe cases due to influenza.

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  • Authors+Show Affiliations

    ,

    Instituto de Salud Pública de Navarra, Pamplona, Spain. jcastilc@navarra.es

    , , , , , , , , , , , , , , , , ,

    Source

    MeSH

    Adolescent
    Adult
    Aged
    Aged, 80 and over
    Case-Control Studies
    Child
    Child, Preschool
    Community-Acquired Infections
    Cross Infection
    Female
    Hospitalization
    Humans
    Infant
    Infant, Newborn
    Influenza Vaccines
    Influenza, Human
    Inpatients
    Male
    Middle Aged
    Outpatients
    Pregnancy
    Prognosis
    Spain
    Young Adult

    Pub Type(s)

    Journal Article
    Research Support, Non-U.S. Gov't

    Language

    eng

    PubMed ID

    23532475

    Citation

    Castilla, Jesús, et al. "Influenza Vaccine Effectiveness in Preventing Outpatient, Inpatient, and Severe Cases of Laboratory-confirmed Influenza." Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America, vol. 57, no. 2, 2013, pp. 167-75.
    Castilla J, Godoy P, Domínguez A, et al. Influenza vaccine effectiveness in preventing outpatient, inpatient, and severe cases of laboratory-confirmed influenza. Clin Infect Dis. 2013;57(2):167-75.
    Castilla, J., Godoy, P., Domínguez, A., Martínez-Baz, I., Astray, J., Martín, V., ... Pumarola, T. (2013). Influenza vaccine effectiveness in preventing outpatient, inpatient, and severe cases of laboratory-confirmed influenza. Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America, 57(2), pp. 167-75. doi:10.1093/cid/cit194.
    Castilla J, et al. Influenza Vaccine Effectiveness in Preventing Outpatient, Inpatient, and Severe Cases of Laboratory-confirmed Influenza. Clin Infect Dis. 2013;57(2):167-75. PubMed PMID: 23532475.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Influenza vaccine effectiveness in preventing outpatient, inpatient, and severe cases of laboratory-confirmed influenza. AU - Castilla,Jesús, AU - Godoy,Pere, AU - Domínguez,Angela, AU - Martínez-Baz,Iván, AU - Astray,Jenaro, AU - Martín,Vicente, AU - Delgado-Rodríguez,Miguel, AU - Baricot,Maretva, AU - Soldevila,Nuria, AU - Mayoral,José María, AU - Quintana,José María, AU - Galán,Juan Carlos, AU - Castro,Ady, AU - González-Candelas,Fernando, AU - Garín,Olatz, AU - Saez,Marc, AU - Tamames,Sonia, AU - Pumarola,Tomás, AU - ,, Y1 - 2013/03/26/ PY - 2013/3/28/entrez PY - 2013/3/28/pubmed PY - 2014/1/22/medline KW - influenza vaccine KW - influenza virus KW - severe influenza KW - vaccine effectiveness SP - 167 EP - 75 JF - Clinical infectious diseases : an official publication of the Infectious Diseases Society of America JO - Clin. Infect. Dis. VL - 57 IS - 2 N2 - BACKGROUND: In most seasons, the influenza vaccine is effective in preventing influenza, but it is not clear whether it is equally effective in preventing mild and severe cases. We designed a case-control study to compare the effectiveness of the influenza vaccine in preventing outpatient, inpatient, and severe or fatal cases of laboratory-confirmed influenza. METHODS: Hospitalized patients (n = 691) with laboratory-confirmed influenza in the 2010-2011 season recruited in 29 Spanish hospitals were individually matched by age, admission/visit date, and province with an outpatient with laboratory-confirmed influenza and an outpatient control. Severe cases were considered those patients admitted to intensive care units or who died in the hospital (n = 177). We compared the influenza vaccine status of controls and outpatient cases, inpatient cases, and severe cases using conditional logistic regression adjusted for potential confounding factors. Severe and nonsevere inpatient influenza cases were compared using unconditional logistic regression. Vaccine effectiveness was (1 - odds ratio) × 100. RESULTS: Vaccine effectiveness was 75% (adjusted odds ratio [AOR], 0.25; 95% confidence interval [CI], .16-.39) in preventing influenza outpatient cases, 60% (AOR, 0.40; 95% CI, .25-.63) in preventing influenza-associated hospitalizations, and 89% (AOR, 0.11; 95% CI, .04-.37) in preventing severe cases. In inpatients, influenza vaccination was associated with a lower risk of severe influenza (AOR, 0.42; 95% CI, .22-.80). CONCLUSIONS: Influenza vaccination prevented influenza cases and hospitalizations and was associated with a better prognosis in inpatients with influenza. The combined effect of these 2 mechanisms would explain the high effectiveness of the vaccine in preventing severe cases due to influenza. SN - 1537-6591 UR - https://www.unboundmedicine.com/medline/citation/23532475/Influenza_vaccine_effectiveness_in_preventing_outpatient_inpatient_and_severe_cases_of_laboratory_confirmed_influenza_ L2 - https://academic.oup.com/cid/article-lookup/doi/10.1093/cid/cit194 DB - PRIME DP - Unbound Medicine ER -