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Completed

NCT Number: NCT02868658

Asymptomatic Flu Project

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.

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Key information

Conditions

Influenza Infections Influenza, Human Orthomyxoviridae Infections RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Edouard Herriot Hospital; Department of Epidemiology, Hygiene and Public Health

Lyon, 69437, France

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Blood sampling

Biological

Nasal Swab

Other

Primary outcomes

  1. Incidence of influenza cases

    Time frame: 6 months after inclusion

    Incidence of asymptomatic and symptomatic influenza per 1000 days at risk among healthcare workers

Secondary outcomes

  1. Fraction of asymptomatic influenza cases

    Time frame: 6 months after inclusion

    Fraction of asymptomatic influenza cases among patients with confirmed influenza infection (seroconversion)

  2. Stratified incidence ratios

    Time frame: 6 months after inclusion

    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

  3. Incidence of influenza-like illness

    Time frame: 6 months after inclusion

    The objective is to calculate the incidence of influenza-like illness without virological confirmation

  4. proportion of health-care workers with Influenza vaccine coverage

    Time frame: 6 months after inclusion

    The objective is to estimate the vaccination coverage against influenza among health care workers

  5. Number of sick-leave days per participating ward

    Time frame: 6 months after inclusion

    The objective is to estimate the professional impact of influenza in a population of healthcare workers

Sponsors and collaborators

Lead sponsor

Hospices Civils de Lyon

Other

Registry information

Official study title

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

Acronym: AFP

Important dates

Study start
2016
Primary completion
2017
Study completion
2017
First posted
Aug 16, 2016
Registry last updated
Dec 19, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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