Abstract

BackgroundIndividuals with cardiopulmonary and other chronic conditions are at increased risk for severe complications of influenza. Few studies have examined influenza vaccine effectiveness (VE) in high-risk groups. We evaluated VE against influenza-associated hospitalization among adults with specific high-risk conditions.MethodsAdults hospitalized with acute respiratory illness (ARI) during the 2015–2016 influenza season were enrolled at eight hospitals participating in the US Hospitalized Adult Influenza Vaccine Effectiveness Network (HAIVEN) study. Respiratory specimens were tested for influenza by reverse transcription PCR. Measures of illness severity, underlying health status, and vaccination were obtained from medical records and enrollment interviews. The presence of high-risk conditions was determined from clinical codes assigned to prior year medical encounters. We estimated VE using a test-negative design as (1 − adjusted odds ratio), comparing odds of PCR-confirmed influenza among vaccinated patients vs. unvaccinated controls. Multivariate logistic regression was adjusted for age, sex, and other factors, stratifying by chronic conditions.ResultsOf 1,467 adults hospitalized with ARI, 236 (16%) had PCR-confirmed influenza; 180 (78%) were A(H1N1)pdm09. In all, 1,358 (93%) had ≥1 high-risk medical condition, and 1,026 (70%) had ≥3 conditions. Cardiovascular (n = 835), metabolic (including diabetes) (n = 773) and lung conditions (n = 692) were most common (figure). Patients with ≥1 high-risk conditions were more likely to be vaccinated (70%) vs. patients not at high risk (31%, P < 0.001). Among all patients, VE against any influenza-associated hospitalization was 50% (95% CI: 31–63). VE was similarly high among patients with neurologic (VE = 64%, 95% CI: 26–83), metabolic (VE = 55%, 95% CI: 30–71), and cardiovascular (VE = 53%, 95% CI: 27–69) conditions, though lower for patients with immunosuppression and malignancy (VE = 20%, 95% CI: −42–54).ConclusionVaccination significantly reduced risk of influenza hospitalization among adults with the most prevalent high-risk cardiovascular, metabolic, and lung conditions. Results support the benefit of vaccinating adults with existing specific chronic conditions. Disclosures H. K. Talbot, sanofi pasteur: Investigator, Research grant. Gilead: Investigator, Research grant. MedImmune: Investigator, Research grant. Vaxinnate: Safety Board, none. Seqirus: Safety Board, none.

Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.