Influenza Vaccine and Readmissions in Patients With Pneumonia

Among hospitalized patients with community acquired pneumonia (CAP), the administration of in-hospital influenza vaccination may be underutilized, and secondary infections due to pneumonia can result in readmissions, according to a study being presented at the CHEST Annual Meeting 2019.

The retrospective study assessed information from the Agency for Healthcare Research and Quality-Healthcare Cost and Utilization Project Nationwide Readmission Database for the year 2014. They included adults with a principal diagnosis of CAP and a procedure diagnosis of influenza vaccination. A total of 825,906 hospital admissions were identified, 1.91% (n=14,047) of which received in-hospital influenza vaccination.

Researchers paired CAP patients who received a vaccine (n=9,777) with those who did not (n=9,777) to adjust for confounders. The overall 30-day readmission rate (primary endpoint) was 11.9%, and the most common reason for readmission was pneumonia (98.1%). Readmission resulted in significantly higher mortality compared with the index admission (7.69% vs. 3.32%; P<0.001). A total of 489,247 hospital days were associated with readmission, and the total healthcare burden was $1 billion in costs and $3.67 billion in charges.

The following factors were associated with a high risk of readmission: in-hospital vaccination (hazard ratio = 0.821; 95% confidence interval, 0.69-0.98; P<0.02), advanced age, Medicare insurance, higher Charlson Comorbidity Index score, atrial fibrillation, acute respiratory failure, and in-hospital oxygen use.

“Although the beneficial effects of influenza vaccination are well described, this is regarded as a primary care-driven service,” the authors noted, despite the fact that it has “significant implications on hospital readmission and morality.”


  1. Ho KS, Sheehan J, Wu L, et al. Missed opportunity for in-hospital vaccination? Influenza vaccination reduces 30-day readmission among patients with community acquired pneumonia: a propensity score match analysis. Presented at the CHEST Annual Meeting 2019. October 19-23, 2019; New Orleans, Louisiana.