Survey of nosocomial influenza in South-western Swiss hospitals during two seasonal epidemics

Abstract

Abstract Nosocomial influenza increases morbidity and mortality in hospitalised patients. No multicentre study analysed its impact in Swiss hospitals yet. This study was conducted From November 1st to April 30th in 2016-2017 and 2017-2018 in 27 acute-care public hospitals in South-western Switzerland. It aimed at describing nosocomial cases of seasonal influenza. During these 2 time-periods, every patient hospitalized for >72 hours that was positively screened by RT-PCR or antigen detection for influenza was retrospectively included in the survey. Policies to prevent influenza were collected in each participating hospital. Characteristics of patients included age, sex, and comorbidities. Included patients were followed-up until discharge or death. Complications and administration of anti-neuraminidases and/or antibiotics were registered. The mean influenza vaccine coverage of healthcare workers (HCW) was 40%. 836 patients were included (98% with a type A influenza virus in 2016-2017; 77% with a type B virus in 2017-2018). Most patients (81%) had an unknown vaccine status. Overall, the incidence of nosocomial influenza was 0.3/100 admissions (0.35/1000 patient-days). The most frequent comorbidities were diabetes (21%), chronic respiratory diseases (18%), and malnutrition (17%). Fever (77%) and cough (66%) were the most frequent symptoms. 70% of patients received anti-neuraminidases, 28% received antibiotics. Infectious complications such as pneumonia were reported in 8%. Overall, the all-cause mortality was 6%. The occurrence of nosocomial influenza underlines the importance of vaccinating patients and HCW, rapidly recognising community or hospital-acquired cases, and applying adequate additional measures to prevent dissemination, including the timely administration of anti-neuraminidases to avoid antibiotic use (and misuse). Key messages Important to encourage patients to be vaccinated against influenza. Apply additional measures in order to prevent influenza dissemination.