Effectiveness of repeated influenza vaccination among the elderly population with high annual vaccine uptake rates during the three consecutive A/H3N2 epidemics

Joon Young Song, Ji Yun Noh, Jin Soo Lee, Seong Heon Wie, Young Keun Kim, Jacob Lee, Hye Won Jeong, Shin Woo Kim, Sun Hee Lee, Kyung Hwa Park, Won Suk Choi, Hee Jin Cheong, Woo Joo Kim

Research output: Contribution to journalArticle

Abstract

Background: Annually, about 80% of the Korean elderly aged ≥65 years receive influenza vaccination. Repeated annual vaccination has been suggested as an important factor of poor influenza vaccine effectiveness (VE), though reported conflicting results. Methods: During the consecutive A/H3N2-dominant influenza seasons between 2012 and 2015, we comparatively evaluated the VE (repeated vs. current season only) against laboratory-confirmed influenza, pneumonia and hospitalization in the elderly aged ≥65 years with influenza-like illness (ILI). Clinical and demographic data were collected prospectively, and vaccination status of prior and current seasons was verified using the immunization registry data of Korean Centers for Disease Control and Prevention. Results: During the first A/H3N2-dominant season in 2012–2013, influenza vaccine showed statistically significant effectiveness against influenza A infection only and when vaccinated in the current season only (VE 53%, 95% CI 15–77). In the latter two seasons (2013–2015 years), the adjusted VE for influenza A was indistinguishable between repeated vaccination and vaccination in the current season only. Conclusion: During consecutive influenza A/H3N2 epidemics, poor influenza vaccine effectiveness may be more pronounced among the elderly population with a high annual vaccine uptake rate.

Original languageEnglish
Pages (from-to)318-322
Number of pages5
JournalVaccine
Volume38
Issue number2
DOIs
Publication statusPublished - 2020 Jan 10

Keywords

  • Antigenic determinants
  • Effectiveness
  • Hospitalization
  • Influenza
  • Pneumonia
  • 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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