The impact of lifestyle behaviors on the acquisition of pandemic (H1N1) 2009 influenza infection: a case-control study

Abstract

Introduction: A novel strain of influenza A H1N1 identified in Mexico and the United States (U.S.) in 2009 spread globally. There is not much data about which people have increased susceptibility to H1N1 infection among the healthy population. The aim of this study was to compare lifestyle behaviors and health habits in subjects with and without a diagnosis of the pandemic 2009 influenza (H1N1) virus infection.

Methods: We conducted a case-control study in a secondary care hospital in South Korea between November 2009 and August 2010. We enrolled cases with H1N1 infection confirmed by a positive result of real-time reverse transcriptase polymerase chain reaction (RT-PCR)

in addition, four age- and sex-matched controls with no history of H1N1 infection or severe acute respiratory illness during the H1N1 pandemic in South Korea, were enrolled (1:4 matching).

Results: During the study period, 34 cases and 136 age- and sex-matched controls were enrolled. The history of contact with H1N1 patients was more predominant among the cases than the controls (p<0.001). The case group had a significantly higher percentage of current smoker (p=0.004) and a lower frequency of regular physical activity compared to the control group (p<0.001). The case group also reported regular vitamin intake per week less than that of the control group. In the multivariable analysis, when history of contact with H1N1 patients was adjusted for, current smoker (adjusted OR 4.418, 95% CI 1.012-19.256

p=0.048) and regular physical activity (adjusted OR 0.051, 95% CI 0.012-0.209

p<0.001) were independently associated with H1N1 infection.

Conclusions: This study shows that regular physical activity has an effect of preventing H1N1 infection and current smokers have increased risk of H1N1 infection