INTRODUCTION: The aims of this study were to understand the geographic extent, risk factors, and attack rate of influenza A (H1N1) pdm09 virus (pH1N1) infection in Shandong Province China and to elucidate influencing factors. METHODS: In January and March 2010, a cross-sectional seroprevalence survey of pH1N1 was carried out. Serum samples from 9022 participants in the survey were subjected to the hemagglutination inhibition assay. RESULTS: Among the 9022 participants, the overall rate of seropositivity against pH1N1 was 22.6%. The weighted rate, adjusted for gender, age, and region, was estimated to be 18.7%. Among 8340 subjects who did not report previous vaccination, the rate was 16.7%, as compared to 50.9% among 682 subjects reporting previous vaccination (p < 0.001). Within the unvaccinated population, the rate of seropositivity among 16-24 and 6-15 y-old subjects was 31.8% and 29.9%, respectively, as compared to 9.6% among subjects aged ≥ 60 y (p < 0.001) and 23% in the 0-5 y age group (p < 0.001). Those aged 6-15 y and aged 16-24 y had higher odds of seropositivity than those aged 0-5 y (odds ratio 1.53 and 1.48, respectively). CONCLUSIONS: These study findings help enhance our understanding of pH1N1 epidemiology and provide valuable information for the vaccination strategy for the influenza season.
INTRODUCTION: The aims of this study were to understand the geographic extent, risk factors, and attack rate of influenza A (H1N1) pdm09 virus (pH1N1) infection in Shandong Province China and to elucidate influencing factors. METHODS: In January and March 2010, a cross-sectional seroprevalence survey of pH1N1 was carried out. Serum samples from 9022 participants in the survey were subjected to the hemagglutination inhibition assay. RESULTS: Among the 9022 participants, the overall rate of seropositivity against pH1N1 was 22.6%. The weighted rate, adjusted for gender, age, and region, was estimated to be 18.7%. Among 8340 subjects who did not report previous vaccination, the rate was 16.7%, as compared to 50.9% among 682 subjects reporting previous vaccination (p < 0.001). Within the unvaccinated population, the rate of seropositivity among 16-24 and 6-15 y-old subjects was 31.8% and 29.9%, respectively, as compared to 9.6% among subjects aged ≥ 60 y (p < 0.001) and 23% in the 0-5 y age group (p < 0.001). Those aged 6-15 y and aged 16-24 y had higher odds of seropositivity than those aged 0-5 y (odds ratio 1.53 and 1.48, respectively). CONCLUSIONS: These study findings help enhance our understanding of pH1N1 epidemiology and provide valuable information for the vaccination strategy for the influenza season.
Authors: Xuxiao Zhang; Ye Shen; Lijie Du; Ran Wang; Bo Jiang; Honglei Sun; Juan Pu; Degui Lin; Ming Wang; Jinhua Liu; Yipeng Sun Journal: Virol J Date: 2015-04-01 Impact factor: 4.099