Seroprevalence and Severity of 2009 Pandemic Influenza A H1N1 in Taiwan

PLoS One

Jien-Wei Liu¹  Yin-Ching Chuang²  Ping-Ing Lee²  Shey-Chiang Su²  Feng-Yee Chang²  Yu-Chia Hsieh²  Tzou-Yien Lin³  Yao-Shen Chen⁴  Cheng-Hsun Chiu⁵  Shih-Cheng Chang⁶  Gwan-Han Shen⁷  Jen-Jyh Lee⁷  Chih-Jung Chen⁷  Shang-Chwen Chang⁷  Yhu-Chering Huang⁸ 

[1] Center for Disease Control, Taiwan, Taipei, Taiwan;College of Medicine, Chang Gung University, Taoyuan, Taiwan;Department of Internal Medicine, Buddhist Tzu Chi General Hospital, Hualien and Tzu Chi University, Hualien, Taiwan;Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan;Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan;Department of Pediatrics, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan;Divisions of Pediatric Infectious Diseases, Department of Pediatrics, Chang Gung Children's Hospital and Chang Gung Memorial Hospital, Taoyuan, Taiwan;Research Center for Emerging Viral Infections, Chang Gung University, Taoyuan, Taiwan

关键词: Taiwan;    Influenza;    Elderly;    Geriatrics;    Vaccination and immunization;    Adolescents;    Age groups;    H1N1;   

DOI  :  10.1371/journal.pone.0024440

学科分类：医学（综合）

来源: Public Library of Science

【 摘 要 】

Background This study is to determine the seroprevalence of the pandemic influenza A H1N1 virus (pH1N1) in Taiwan before and after the 2009 pandemic, and to estimate the relative severity of pH1N1 infections among different age groups. Methodology/Principal Findings A total of 1544 and 1558 random serum samples were collected from the general population in Taiwan in 2007 and 2010, respectively. Seropositivity was defined by a hemagglutination inhibition titer to pH1N1 (A/Taiwan/126/09) ≥1:40. The seropositivity rate of pH1N1 among the unvaccinated subjects and national surveillance data were used to compare the proportion of infections that led to severe diseases and fatalities among different age groups. The overall seroprevalence of pH1N1 was 0.91% (95% confidence interval [CI] 0.43–1.38) in 2007 and significantly increased to 29.9% (95% CI 27.6–32.2) in 2010 (p<0.0001), with the peak attack rate (55.4%) in 10–17 year-old adolescents, the lowest in elderly ≥65 years (14.1%). The overall attack rates were 20.6% (188/912) in unvaccinated subjects. Among the unvaccinated but infected populations, the estimated attack rates of severe cases per 100,000 infections were significantly higher in children aged 0–5 years (54.9 cases, odds ratio [OR] 4.23, 95% CI 3.04–5.90) and elderly ≥ 65years (22.4 cases, OR 2.76, 95% CI 1.99–3.83) compared to adolescents aged 10–17 years (13.0 cases). The overall case-fatality rate was 0.98 per 100,000 infections without a significant difference in different age groups. Conclusions/Significance Pre-existing immunity against pH1N1 was rarely identified in Taiwanese at any age in 2007. Young children and elderly – the two most lower seroprotection groups showed the greatest vulnerability to clinical severity after the pH1N1 infections. These results imply that both age groups should have higher priority for immunization in the coming flu season.

【 授权许可】

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