I1. Adult Vaccines
Oral Abstract Submission
Evan J. Anderson, MD
Infectious Diseases Physician
Emory University, Atlanta VA Medical Center
Disclosure: AbbVie: Consultant
MedImmune: Scientific Research Study Investigator
Merck: Scientific Research Study Investigator
Micron Biomedical: Scientific Research Study Investigator
Novavax: Grant/Research Support
PaxVax: Scientific Research Study Investigator
Pfizer: Grant/Research Support, Advisor or Review Panel member
Regeneron: Scientific Research Study Investigator
Sanofi Pasteur: Scientific Research Study Investigator
Influenza vaccination may reduce illness severity among those with influenza; however, data are limited. We determined whether outcomes were less severe among vaccinated compared to unvaccinated adults hospitalized with influenza over 5 seasons.
Methods : We included adults (≥18 years) hospitalized with laboratory-confirmed influenza during seasons 2013-14 through 2017-18 and identified through the U.S. Influenza Hospitalization Surveillance Network (FluSurv-NET). Vaccination status was obtained through medical records, vaccine registries and interviews. We excluded patients who were institutionalized, did not receive antivirals, or had unknown vaccine status or vaccine receipt <14 days before positive influenza test. We used inverse propensity score weighting to balance differences between vaccinated and unvaccinated groups and multivariable logistic and competing risk regression to evaluate the association between vaccination and outcomes including pneumonia, intensive care unit (ICU) admission, mechanical ventilation (MV), death, and ICU and hospital length of stay (LOS) in days. Models were adjusted for season and admission timing in relation to timing of antiviral treatment, symptom onset and season peak.
Results : Among 67,452 adults hospitalized with influenza, 43,608 were included; 47% were 18-64 years (38% vaccinated) and 53% were ≥65 years (65% vaccinated). Among patients with influenza A(H1N1)pdm09, vaccination was associated with decreased odds of ICU admission (odds ratio (OR) 0.81; OR 0.72) and MV (OR 0.66; OR 0.54) in adults 18-64 and ≥65 years, respectively; decreased odds of pneumonia (OR 0.83), death (OR 0.64) and shortened ICU LOS (relative hazard (RH) 0.82) in adults 18-64 years; and shortened hospital LOS (RH 0.91) in adults ≥65 years (Figure). Vaccination was not associated with attenuation of severe outcomes in patients with influenza A(H3N2) and B.
Conclusion : Vaccination was associated with reduced odds of severe outcomes, including death, by up to 36% in adults hospitalized with influenza A(H1N1)pdm09. All adults without contraindications should receive annual influenza vaccination as there is evidence that it can improve outcomes among those who develop influenza despite vaccination.