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J Infect Dis. 2015 May 15;211(10):1529-40. doi: 10.1093/infdis/jiu647. Epub 2014 Nov 18.

Influenza vaccine effectiveness in the United States during 2012-2013: variable protection by age and virus type.

Author information

1
Marshfield Clinic Research Foundation, Wisconsin.
2
Centers for Disease Control and Prevention, Atlanta, Georgia.
3
Baylor Scott and White Health, Texas A&M Health Science Center College of Medicine, Temple.
4
Baylor College of Medicine, Houston, Texas.
5
University of Pittsburgh, Pennsylvania.
6
Group Health Cooperative, Seattle, Washington.
7
University of Michigan, Ann Arbor.

Abstract

BACKGROUND:

During the 2012-2013 influenza season, there was cocirculation of influenza A(H3N2) and 2 influenza B lineage viruses in the United States.

METHODS:

Patients with acute cough illness for ≤7 days were prospectively enrolled and had swab samples obtained at outpatient clinics in 5 states. Influenza vaccination dates were confirmed by medical records. The vaccine effectiveness (VE) was estimated as [100% × (1 - adjusted odds ratio)] for vaccination in cases versus test-negative controls.

RESULTS:

Influenza was detected in 2307 of 6452 patients (36%); 1292 (56%) had influenza A(H3N2), 582 (25%) had influenza B/Yamagata, and 303 (13%) had influenza B/Victoria. VE was 49% (95% confidence interval [CI], 43%-55%) overall, 39% (95% CI, 29%-47%) against influenza A(H3N2), 66% (95% CI, 58%-73%) against influenza B/Yamagata (vaccine lineage), and 51% (95% CI, 36%-63%) against influenza B/Victoria. VE against influenza A(H3N2) was highest among persons aged 50-64 years (52%; 95% CI, 33%-65%) and persons aged 6 months-8 years (51%; 95% CI, 32%-64%) and lowest among persons aged ≥65 years (11%; 95% CI, -41% to 43%). In younger age groups, there was evidence of residual protection from receipt of the 2011-2012 vaccine 1 year earlier.

CONCLUSIONS:

The 2012-2013 vaccines were moderately effective in most age groups. Cross-lineage protection and residual effects from prior vaccination were observed and warrant further investigation.

KEYWORDS:

influenza; medically attended influenza; vaccine effectiveness

PMID:
25406334
PMCID:
PMC4407759
DOI:
10.1093/infdis/jiu647
[Indexed for MEDLINE]
Free PMC Article

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