1457. Influenza Vaccine Effectiveness Against Influenza-Associated Pneumonia and Pneumococcal Pneumonia in Older Adults: A Prospective Test-Negative Design Study
Session: Poster Abstract Session: Influenza and Influenza Vaccines
Friday, October 6, 2017
Room: Poster Hall CD
Posters
  • IDWeek_2017_Suzuki.pdf (403.2 kB)
  • Background: Studies have shown that influenza vaccines are effective in preventing influenza-associated acute respiratory illnesses in older adults. However, the influenza vaccine effectiveness (IVE) against influenza-associated pneumonia in this age group has not been established. No study has formally investigated the IVE against pneumococcal pneumonia.

    Methods: This study was conducted as part of a multicenter prospective investigation of adult pneumonia by the Adult Pneumonia Study Group-Japan (APSG-J). All community-onset pneumonia patients aged 65 years or older who visited a community-based hospital in Chiba, central Japan were enrolled to the study from December 2012 to January 2014. Sputum samples were tested for 13 viruses and 6 bacteria by multiplex PCR assays. Patients were diagnosed as influenza-associated pneumonia if sputum PCR assays were positive for influenza A or B. Patients were diagnosed as pneumococcal pneumonia if sputum culture yielded pneumococcus, sputum PCR assays were positive for both ply and lytA genes, or a urinary antigen test showed a positive result. Patients were considered vaccinated if they had received at least one dose of seasonal inactivated influenza vaccine in the 12 months before the hospital visit. A test-negative design was applied to estimate the IVE for influenza-associated pneumonia and pneumococcal pneumonia. IVEs were calculated as (1 – odds ratio) × 100%.

    Results: A total of 1044 patients were enrolled to the study. Among them, 49 (4.7%) were influenza-associated pneumonia, and 168 (16.1%) were pneumococcal pneumonia. The adjusted IVE against influenza-associated pneumonia was 57.2% (95% CI, 17.9% to 76.8%). The adjusted IVE against pneumococcal pneumonia was 31.7% (0.6% to 53.1%); the estimate did not change before and after controlling for pneumococcal vaccination history.

    Conclusion: Influenza vaccines effectively prevent influenza-associated pneumonia in older adults. Influenza vaccines are also associated with decreased risk of pneumococcal pneumonia in this age group, while some residual confounding may remain.

    Motoi Suzuki, MD1, Bhim Gopal Dhoubhadel, PhD2, Naoko Katsurada, MD3, Eiichiro Sando, MD1,3, Tomoko Ishifuji, MD1, Norihiro Kaneko, MD3, Makito Yaegashi, MD4, Naoto Hosokawa, MD3, Masahiro Aoshima, MD3, Koya Ariyoshi, M.D.1, Konosuke Morimoto, M.D., Ph.D.5 and Adult Pneumonia Study Group-Japan, (1)Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan, (2)School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan, (3)Kameda Medical Center, Kamogawa, Japan, (4)Department of General Internal Medicine, Kameda Medical Center, Kamogawa, Japan, (5)Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan

    Disclosures:

    M. Suzuki, None

    B. G. Dhoubhadel, None

    N. Katsurada, None

    E. Sando, None

    T. Ishifuji, None

    N. Kaneko, None

    M. Yaegashi, None

    N. Hosokawa, None

    M. Aoshima, None

    K. Ariyoshi, None

    K. Morimoto, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 4th with the exception of research findings presented at the IDWeek press conferences.