Incidence of Asymptomatic and Symptomatic Influenza Among Healthcare Workers: A Multicenter Prospective Cohort Study. (4th August 2020)

• Record Type: Journal Article
• Authors: Bénet, Thomas; Amour, Sélilah; Valette, Martine; Saadatian-Elahi, Mitra; Aho-Glélé, Ludwig Serge; Berthelot, Philippe; Denis, Marie-Agnès; Grando, Jacqueline; Landelle, Caroline; Astruc, Karine; Paris, Adeline; Pillet, Sylvie; Lina, Bruno; Vanhems, Philippe
• Is Part Of: Clinical infectious diseases. Volume 72:Number 9(2021)
• Page Start: e311
• Page End: e318
• Publication Date: 2020-08-04
• Subjects: asymptomatic influenza -- healthcare workers -- prospective cohort -- incidence -- nosocomial; Communicable diseases -- Periodicals; 616.905
• DOI: 10.1093/cid/ciaa1109
• Languages: English
• ISSNs: 1058-4838

Abstract

Abstract: Background: Influenza is an important cause of viral hospital-acquired infection involving patients, healthcare workers (HCW), and visitors. The frequency of asymptomatic influenza among HCW with possible subsequent transmission is poorly described. The objective is to determine the cumulative incidence of asymptomatic, paucisymptomatic, and symptomatic influenza among HCW. Method: A multicenter prospective cohort study was done in 5 French university hospitals, including 289 HCW during the 2016–2017 influenza season. HCW had 3 physical examinations (time [T] 0, before epidemic onset; T.1, before epidemic peak; T.2, T.3, after epidemic peak). A blood sample was taken each time for influenza serology and a nasal swab was collected at T1 and T2 for influenza detection by polymerase chain reaction (PCR). Positive influenza was defined as either a positive influenza PCR, and/or virus-specific seroconversion against influenza A, the only circulating virus, with no vaccination record during follow-up. Symptoms were self-reported daily between T1 and T2. Cumulative incidence of influenza was stratified by clinical presentation per 100 HCW. Results: Of the 289 HCW included, 278 (96%) completed the entire follow-up. Overall, 62 HCW had evidence of influenza of whom 46.8% were asymptomatic, 41.9% were paucisymptomatic, and 11.3% were symptomatic. Cumulative influenza incidence was 22.3% (95% confidence interval [CI]: 17.4%–27.2%). Cumulative incidence of asymptomatic influenza was 5.8% (95% CI: 3.3%–9.2%), 13.7% (95% CI: 9.9%–18.2%) for paucisymptomatic influenza, and 2.9% (95% CI: 1.3%–5.5%) for symptomatic influenza. Conclusions: Asymptomatic and paucisymptomatic influenza were frequent among HCW, representing 47% and 42% of the influenza burden, respectively. These findings highlight the importance of systematic implementation of infection control measures among HCW regardless of respiratory symptoms from preventing nosocomial transmission of influenza. Clinical Trials Registration: NCT02868658. Abstract : Among 278 healthcare workers (HCW) included prospectively during the 2016–2017 winter season, asymptomatic and paucisymptomatic influenza are frequent in this population. Then the HCW with mild or lack of symptoms might contribute to the spread of influenza in hospitals.