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Eur J Public Health. 2018 Feb 1;28(1):150-155. doi: 10.1093/eurpub/ckx130.

Smoking may increase the risk of influenza hospitalization and reduce influenza vaccine effectiveness in the elderly.

Author information

1
Department of Health, Generalitat of Catalonia, Barcelona, Spain.
2
CIBER Epidemiology and Public Health, Madrid, Spain.
3
IRBLleida, University of Lleida, Lleida, Spain.
4
Public Health Institute of Navarra, IdiSNA, Pamplona, Spain.
5
University of Barcelona, Barcelona, Spain.
6
Surveillance Service, Andalusian Government, Seville, Spain.
7
University of Leon, Leon, Spain.
8
Area of Epidemiology, Community of Madrid, Madrid, Spain.
9
Hospital de Galdakao, Unansolo, Spain.
10
University of Valencia, Valencia, Spain.

Abstract

Background:

Through its effects on the immune system, smoking may facilitate influenza virus infection, its severity and its most frequent complications. The objective was to investigate the smoking history as a risk factor for influenza hospitalization and influenza vaccine effectiveness in elderly smokers/ex-smokers and non-smokers.

Methods:

We carried out a multicenter case-control study in the 2013-2014 and 2014-2015 influenza seasons. Cases aged ≥65 years and age-, sex-matched controls were selected from 20 Spanish hospitals. We collected epidemiological variables, comorbidities, vaccination history and the smoking history. The risk of hospitalization due to smoking (current smokers and ex-smokers) was determined using the adjusted odds ratio (aOR) with conditional logistic regression models. Vaccine effectiveness (VE) was calculated using the formula: VE = (1 - aOR) × 100.

Results:

We studied 728 cases and 1826 controls. Cases had a higher frequency of smoking (47.4% vs 42.1%). Smoking was associated with an increased risk of influenza hospitalization (aOR = 1.32, 95% CI: 1.04-1.68). Influenza vaccine effectiveness in preventing hospitalization was 21% (95% CI: -2 to 39) in current/ex-smokers and 39% in non-smokers (95% CI: 22-52).

Conclusions:

A history of smoking may increase the risk of hospitalization in smokers and ex-smokers. Preventing smoking could reduce hospitalizations due to influenza. Smokers and ex-smokers should be informed of the risk of hospitalization due to influenza infection, and encouraged to stop smoking. Smokers should be considered an at-risk group to be aggressively targeted for routine influenza vaccination.

PMID:
29020390
DOI:
10.1093/eurpub/ckx130
[Indexed for MEDLINE]

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