J Hosp Infect

. 2021 Jan 7;S0195-6701(21)00005-0.
doi: 10.1016/j.jhin.2020.12.020. Online ahead of print.
Nosocomial influenza in southwestern Swiss hospitals during two seasonal epidemics: an observational study

Laetitia Qalla-Widmer 1 , Delphine Héquet 2 , Nicolas Troillet 3 , Christiane Petignat 1 , Carlo Balmelli 4 , Cécile Bassi 5 , Cristina Bellini 6 , Jean-Philippe Chave 6 , Alain Cometta 6 , Laurent Christin 6 , Olivier Clerc 7 , Oscar Daher 6 , Urs Fuehrer 8 , Oscar Marchetti 6 , Laurent Merz 6 , Vera Portillo 9 , Gérard Pralong 6 , Laurent Sandoz 6 , Laurence Senn 10 , Frédéric Tâche 6 , Anne Iten 11



This study was conducted during two seasonal influenza epidemics from 2016 to 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 included in the survey. 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 median 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 0.5/100 admissions (0.35/1000 patient-days). The most frequent comorbidities were diabetes (20%), chronic respiratory diseases (19%), and malnutrition (17%). Fever (77%) and cough (66%) were the most frequent symptoms. 71% of patients received anti-neuraminidases, 28% received antibiotics. Infectious complications such as pneumonia were reported in 9%. 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).

Keywords: hospitals; influenza; nosocomial.