Effect of a multimodal strategy for prevention of nosocomial influenza: a retrospective study at Grenoble Alpes University Hospital from 2014 to 2019.

backgroundA multimodal strategy to prevent nosocomial influenza was implemented in 2015-2016 in Grenoble Alpes University Hospital. Three modalities were implemented in all units: promotion of vaccination among healthcare workers, epidemiologic surveillance and communication campaigns. Units receiving a high number of patients with influenza implemented 2 additional modalities: improvement of diagnosis capacities and systematic surgical mask use. The main objective was to assess the effectiveness of the strategy for reducing the risk of nosocomial influenza.

methodsA study was conducted retrospectively investigating 5 epidemic seasons (2014-2015 to 2018-2019) including all patients hospitalized with a positive influenza test at Grenoble Alpes University Hospital. The weekly number of nosocomial influenza cases was analyzed by Poisson regression and incidence rate ratios (IRR) were estimated.

resultsA total of 1540 patients, resulting in 1559 stays, were included. There was no significant difference between the 5 influenza epidemic seasons in the units implementing only 3 measures. In the units implementing the 5 measures, there was a reduction of nosocomial influenza over the seasons when the strategy was implemented compared to the 2014-2015 epidemic season (IRR = 0.56, 95% CI = 0.23-1.34 in 2015-2016; IRR = 0.39, 95% CI = 0.19-0.81 in 2016-2017; IRR = 0.50, 95% CI = 0.24-1.03 in 2017-2018; IRR = 0.48, 95% CI = 0.23-0.97 in 2018-2019).

conclusionsOur data mainly suggested that the application of the strategy with 5 modalities, including systematic surgical mask use and rapid diagnosis, seemed to reduce by half the risk of nosocomial influenza. Further data, including medico-economic studies, are necessary to determine the opportunity of extending these measures at a larger scale.