Format

Send to

Choose Destination
Clin Infect Dis. 2014 Nov 15;59(10):1375-85. doi: 10.1093/cid/ciu680. Epub 2014 Sep 29.

Impact of repeated vaccination on vaccine effectiveness against influenza A(H3N2) and B during 8 seasons.

Author information

1
Center for Clinical Epidemiology and Population Health, Marshfield Clinic Research Foundation, Wisconsin.
2
Influenza Division, Centers for Disease Control and Prevention, Atlanta, Georgia.
3
Integrated Research and Development Laboratory, Marshfield Clinic Research Foundation.
4
Department of Pathobiological Sciences, University of Wisconsin School of Veterinary Medicine, Wisconsin National Primate Research Center, Madison.

Abstract

BACKGROUND:

Recent studies suggest that influenza vaccination in the previous season may influence the effectiveness of current-season vaccination, but this has not been assessed in a single population over multiple years.

METHODS:

Patients presenting with acute respiratory illness were prospectively enrolled during the 2004-2005 through 2012-2013 influenza seasons. Respiratory swabs were tested for influenza and vaccination dates obtained from a validated registry. Vaccination status was determined for the current, previous, and prior 5 seasons. Vaccine effectiveness (VE) was calculated for participants aged ≥9 years using logistic regression models with an interaction term for vaccination history.

RESULTS:

There were 7315 enrollments during 8 seasons; 1056 (14%) and 650 (9%) were positive for influenza A(H3N2) and B, respectively. Vaccination during current only, previous only, or both seasons yielded similar protection against H3N2 (adjusted VE range, 31%-36%) and B (52%-66%). In the analysis using 5 years of historical vaccination data, current season VE against H3N2 was significantly higher among vaccinated individuals with no prior vaccination history (65%; 95% confidence interval [CI], 36%-80%) compared with vaccinated individuals with a frequent vaccination history (24%; 95% CI, 3%-41%; P = .01). VE against B was 75% (95% CI, 50%-87%) and 48% (95% CI, 29%-62%), respectively (P = .05). Similar findings were observed when analysis was restricted to adults 18-49 years.

CONCLUSIONS:

Current- and previous-season vaccination generated similar levels of protection, and vaccine-induced protection was greatest for individuals not vaccinated during the prior 5 years. Additional studies are needed to understand the long-term effects of annual vaccination.

KEYWORDS:

influenza; vaccine effectiveness

PMID:
25270645
PMCID:
PMC4207422
DOI:
10.1093/cid/ciu680
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Silverchair Information Systems Icon for PubMed Central
Loading ...
Support Center