CHEST 2019 — In-hospital influenza vaccine associated with reduced CAP readmissions

  • Keren Landman, MD
  • Conference Reports
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  • Among patients hospitalized for community-acquired pneumonia (CAP), receiving in-hospital influenza vaccine was associated with reduced risk of 30-day readmission and lower mortality in readmitted patients.

Why this matters

  • Concurrent influenza infection and bacterial pneumonia accounts for a high proportion of deaths during flu season. 

Study design

  • Retrospective review using records from the year 2014 in the AHRQ-HCUP Nationwide Readmission Database.
  • 9777 patients hospitalized for CAP who did and did not receive in-hospital influenza vaccination were propensity-matched.
  • Independent risk factors for readmission were identified.
  • Funding: None.

Key results

  • Patients who received in-hospital influenza vaccination during their initial CAP admission had lower risk of readmission (HR, 0.82 [95% CI, 0.69-0.98]).
  • Mortality among nonvaccinated patients was more than twice that among vaccinated patients on readmission (5.5% vs 1.3%).
    • Mortality among nonvaccinated patients was also higher than among vaccinated patients during the index admission (2.9% vs 1.1%).
  • Pneumonia was the most common principal diagnosis among readmitted patients, and influenza was the principal diagnosis in 3.8% of cases.


  • Retrospective analysis.
  • Higher mortality among nonvaccinated group at baseline is suggestive of differences between groups not accounted for in propensity matching.

Expert commentary

  • In a press release, Michelle Cao, MD, member of the American College of Chest Physicians Scientific Presentations and Awards Committee and Clinical Associate Professor at Stanford University, California, was quoted as commenting: “This study highlights the importance of implementing influenza vaccination, specifically in patients with a diagnosis of community-acquired pneumonia." She continued: "Influenza vaccination is considered a ‘primary care-driven service," and "the question is how to best develop practices that would ensure successful vaccination in the inpatient setting, specifically for patients admitted for community-acquired pneumonia. Successful protocols would potentially be used in other inpatient populations as well." Dr. Cao was not involved with the study.