Safety of Seasonal Influenza Vaccination in Hospitalized Surgical Patients A Cohort Study

Background: Despite recommendations to vaccinate surgical inpatients against influenza, vaccination rates remain low in this population, due in part to concerns about potential negative effects on postsurgical care. Objective: To evaluate whether influenza vaccination in the perioperative period increases health care utilization and evaluations for postsurgical infection after discharge. Design: Retrospective cohort study. Setting: Members of Kaiser Permanente Southern California. Participants: Patients aged 6 months or older who had inpatient surgery with admission and discharge between 1 September and 31 March from 2010 to 2013. Measurements: All influenza vaccinations administered between 1 August and 30 April in the 2010-2011, 2011-2012, and 2012-2013 influenza seasons. Outcomes included rates of outpatient visits, readmission, emergency department (ED) visits, fever (temperature >= 38.0 degrees C), and clinical laboratory evaluations for infection (urine culture, complete blood count, blood culture, and wound culture) in the 7 days after discharge. Results: Of the 42 777 surgeries included in adjusted analyses, vaccine was administered during hospitalization in 6420. No differences were detected between the vaccinated and unvaccinated groups in risk for inpatient visits (rate ratio [RR], 1.12 [95% CI, 0.96 to 1.32]), ED visits (RR, 1.07 [CI, 0.96 to 1.20]), postdischarge fever (RR, 1.00 [CI, 0.76 to 1.31]), or clinical evaluations for infection (RR, 1.06 [CI, 0.99 to 1.13]). A marginal increase in risk for outpatient visits (RR, 1.05 [CI, 1.00 to 1.10]; P = 0.032) was found. Limitation: The study did not distinguish between planned and unplanned readmissions or outpatient visits. Conclusion: No strong evidence of increased risk for adverse outcomes was found in comparisons of patients who received influenza vaccine during a surgical hospitalization and those who did not. The data support the recommendation to vaccinate surgical inpatients against influenza.