Effectiveness of the pandemic influenza A/H1N1 2009 monovalent vaccine in Korea

Joon Young Song, Hee Jin Cheong, Jung Yeon Heo, Ji Yun Noh, Won Suk Choi, Dae Won Park, Jacob Lee, Hye Won Jeong, Sae Yoon Kee, Woo Joo Kim

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    30 Citations (Scopus)


    The 2009 influenza pandemic was caused by a novel triple-reassortant influenza A/H1N1 virus that was further recombined with a Eurasian pig flu virus. Vaccination is a key countermeasure for disease; however, little data assessing vaccine effectiveness (VE) against the pandemic H1N1 virus are available. We conducted a matched case-control study to assess effectiveness of the 2009 influenza A/H1N1 monovalent vaccine against laboratory-confirmed, medically attended influenza patients. Subjects included in the study were ≥10 years of age and were treated at five university hospitals in the Republic of Korea (ROK) from December 2009 through March 2010. For subjects visiting outpatient clinics with influenza-like illness (ILI), real time reverse transcription polymerase chain reaction (rRT-PCR) was used to diagnose 2009 H1N1 influenza virus infection. Subjects with positive rRT-PCR were classified as cases, while those testing negative were controls. A valid vaccination corresponded to ≥14 days between receiving a dose of vaccine and symptom onset. Overall, 416 ILI subjects were analyzed, and 60 (14.4%) were vaccinated with the 2009 influenza A/H1N1 monovalent vaccine. The overall VE against pandemic 2009 A/H1N1 virus illness after adjustment for age group and presence of chronic medical conditions was 73.4% (95% confidence interval [CI] = 49.1-86.1%). Both vaccine formulations (unadjuvanted and MF-59 adjuvanted) showed a statistically significant VE. In conclusion, the 2009 influenza A/H1N1 monovalent vaccine was substantially protective against pandemic influenza in the ROK during the 2009-2010 season.

    Original languageEnglish
    Pages (from-to)1395-1398
    Number of pages4
    Issue number7
    Publication statusPublished - 2011 Feb 4


    • 2009 H1N1
    • Effectiveness
    • Influenza
    • Vaccination

    ASJC Scopus subject areas

    • Molecular Medicine
    • Immunology and Microbiology(all)
    • veterinary(all)
    • Public Health, Environmental and Occupational Health
    • Infectious Diseases


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