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. 2015;11(5):1088-93.
doi: 10.1080/21645515.2015.1016668.

Association between monovalent influenza A (H1N1) pdm09 vaccine and pneumonia among the elderly in the 2009-2010 season in Japan: A case-control study

Kyoko Kondo  1 , Kanzo Suzuki, Masakazu Washio, Satoko Ohfuji, Wakaba Fukushima, Akiko Maeda, Yoshio Hirota; Pneumonia in Elderly People Study Group
Collaborators, Affiliations

Association between monovalent influenza A (H1N1) pdm09 vaccine and pneumonia among the elderly in the 2009-2010 season in Japan: A case-control study

Kyoko Kondo et al. Hum Vaccin Immunother. 2015.

Erratum in

  • Corrigendum.
    [No authors listed] [No authors listed] Hum Vaccin Immunother. 2015;11(10):2510. doi: 10.1080/21645515.2015.1082393. Hum Vaccin Immunother. 2015. PMID: 26376017 Free PMC article. No abstract available.

Abstract

We investigated the association between monovalent influenza A (H1N1) pdm09 (H1N1pdm) vaccine and pneumonia in elderly people. Study design was a hospital-based, matched case-control study. Cases comprised patients ≥ 65 years old who had been newly diagnosed with pneumonia. For each case, 2 controls were defined as individuals with other diseases (not pneumonia) who were matched by sex, age, entry date, and the visited hospital. Study period was the interval from 1 September 2009 until 30 September 2010. Because a pandemic of influenza A (H1N1) occurred during study period, we analyzed selected subjects who had enrolled during the influenza A (H1N1) pandemic. We calculated the odds ratios (ORs) and 95% confidence intervals (CIs) for pneumonia in H1N1pdm-vaccinated subjects compared with unvaccinated subjects using a conditional logistic regression model to assess the association between H1N1pdm vaccine and pneumonia. The subjects during the period of the influenza A (H1N1) pandemic were 20 cases and 40 controls. Subjects who had received H1N1pdm vaccine showed a significantly decreased OR for pneumonia (OR = 0.10, 95% CI = 0.01-0.98) compared with unvaccinated subjects. In conclusion, H1N1pdm vaccination may have prevented pneumonia among the elderly during the 2009-2010 influenza A (H1N1) pandemic in Japan.

Keywords: ADL, activities of daily living; CI, confidence interval; COPD, chronic obstructive pulmonary disease; H1N1pdm, monovalent influenza A (H1N1) pdm09; OR, odds ratio; TIV, trivalent seasonal influenza vaccine; effectiveness; elderly people; matched case-control study; monovalent influenza A (H1N1) pdm09 vaccine; pneumonia.

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Figures

Figure 1.
Figure 1.
(A) Study period and weekly cases of influenza in Japan from week 35 of 2009 to week 39 of 2010. (B) Study period and monthly reports of isolation/detection of influenza viruses in Japan from August 2009 to September 2010.
See this image and copyright information in PMC

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