26436611

PMC4688454

Importance

Few studies have evaluated the relationship between influenza vaccination and pneumonia, a serious complication of influenza infection.

Objective

Assess the association between influenza vaccination status and hospitalization for community-acquired laboratory-confirmed influenza pneumonia.

Design, Setting and Participants

The Etiology of Pneumonia in the Community (EPIC) study was a prospective observational multicenter study of hospitalizations for community-acquired pneumonia conducted from January 2010 through June 2012 in four US sites. We used EPIC study data from patients ≥6 months of age with laboratory-confirmed influenza infection and verified vaccination status during the influenza seasons, and excluded patients with recent hospitalization, from chronic care residential facilities, and with severe immunosuppression. Logistic regression was used to calculate odds ratios, comparing the odds of vaccination between influenza-positive (cases) and influenza-negative (controls) pneumonia patients, controlling for demographics, co-morbidities, season, study site and timing of disease onset. Vaccine effectiveness was estimated as (1-odds ratio) × 100%.

Exposure

Influenza vaccination, verified through record review.

Outcome

Influenza pneumonia, confirmed by real-time reverse transcription-polymerase chain reaction performed on nasal/oropharyngeal swabs.

Results

Overall, 2767 patients hospitalized for pneumonia were eligible for the study; 162 (5.9%) were influenza positive. Twenty-eight (17%) of 162 cases with influenza-associated pneumonia and 766 (29%) of 2605 controls with influenza-negative pneumonia had been vaccinated. The adjusted odds ratio of prior influenza vaccination between cases and controls was 0.43 (95% CI 0.28–0.68 [estimated vaccine effectiveness 56.7% (95% CI 31.9–72.5)]).

Conclusions and relevance

Among children and adults hospitalized with community-acquired pneumonia, those with laboratory confirmed influenza-associated pneumonia, compared to those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.

CDC Public Access

U18 IP000488/IP/NCIRD CDC HHS/United States