Asymptomatic Flu Project

Study Overview
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Brief Summary
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Although clinical presentation of influenza is often symptomatic, asymptomatic cases also occur. The knowledge of the incidence of asymptomatic influenza among healthcare workers is very important because of the risk of cross-transmission to hospitalized patients. The principal objective of the study is to estimate the incidence of symptomatic and asymptomatic influenza among healthcare workers in short-stay wards. The results of this study will lead to a better understanding of the burden of asymptomatic influenza among healthcare workers and might be used as an argument to increase influenza vaccine coverage among healthcare workers.

Official Title
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Incidence of Symptomatic and Asymptomatic Influenza Among Healthcare Workers : A Multicenter Cohort Study

Conditions
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Influenza

Intervention / Treatment
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* Biological: Blood sampling
* Other: Nasal swab


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Volunteer health-care workers Working in the following wards: short-stay, inpatient (including ICU) and emergency Exclusion Criteria: Presence of influenza symptoms at enrolment Programmed absence (maternity leave, vacation, etc.) Administrative agents

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Health-care workers<br>Health-care workers recruited in the study will have blood sampling and naso-pharyngeal bottle-brush sampling | Biological: Blood sampling<br> <br> Other: Nasal swab<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of influenza cases | Incidence of asymptomatic and symptomatic influenza per 1000 days at risk among healthcare workers | 6 months after inclusion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fraction of asymptomatic influenza cases | Fraction of asymptomatic influenza cases among patients with confirmed influenza infection (seroconversion) | 6 months after inclusion | 
| Stratified incidence ratios | The objective is to compare the proportion of asymptomatic influenza among vaccinated and unvaccinated healthcare workers, stratified on the type of influenza virus , gender, age, and other covariates | 6 months after inclusion | 
| Incidence of influenza-like illness | The objective is to calculate the incidence of influenza-like illness without virological confirmation | 6 months after inclusion | 
| proportion of health-care workers with Influenza vaccine coverage | The objective is to estimate the vaccination coverage against influenza among health care workers | 6 months after inclusion | 
| Number of sick-leave days per participating ward | The objective is to estimate the professional impact of influenza in a population of healthcare workers | 6 months after inclusion | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Influenza, health care workers, nosocomial, asymptomatic, France