title: Effectiveness of the pandemic influenza A/H1N1 2009 monovalent vaccine in Korea.
abstract: 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.
authors.affiliation: Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea.
authors.forename: Joon Young
authors.initials: JY
authors.lastname: Song
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Cheong
authors.forename: Jung Yeon
authors.initials: JY
authors.lastname: Heo
authors.forename: Ji Yun
authors.initials: JY
authors.lastname: Noh
authors.forename: Won Suk
authors.initials: WS
authors.lastname: Choi
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Park
authors.forename: Jacob
authors.initials: J
authors.lastname: Lee
authors.forename: Hye Won
authors.initials: HW
authors.lastname: Jeong
authors.forename: Sae Yoon
authors.initials: SY
authors.lastname: Kee
authors.forename: Woo Joo
authors.initials: WJ
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000554:Ambulatory Care Facilities; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006785:Hospitals, University; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007251:Influenza, Human / Q000175:diagnosis / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D056910:Republic of Korea; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines