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Transmission of Influenza Virus From Asymptomatic Healthcare Workers and Inpatients in the Acute Care Hospital Setting (TransFLUas)

This study has been completed.
Sponsor:
ClinicalTrials.gov Identifier:
NCT02478905
First Posted: June 23, 2015
Last Update Posted: October 31, 2017
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
Collaborator:
Schweizerischer Nationalfonds
Information provided by (Responsible Party):
University of Zurich
  Purpose
The epidemiology and transmission dynamics of influenza in hospitals are only poorly understood, particularly with respect to subjects without symptoms of influenza infection (e.g. without fever, cough, sore throat, nasal congestion, weakness, headache, loss of appetite, or myalgia). Knowledge about whether asymptomatic subjects are able to transmit influenza is of major importance. If they do transmit influenza, vaccination of patients and healthcare workers (HCW) before start of the influenza season, the permanent use of masks by HCW during influenza season, and quarantine for previously exposed inpatients may be the only available measures to reduce the number of influenza transmission events from asymptomatic subjects in acute care hospitals. Closure of this knowledge gap would be of major benefit to infection prevention and control recommendations, and may in turn reduce morbidity and mortality associated with influenza in hospitals through improved patient management.

Condition Intervention
Human Influenza Other: Influenza

Study Type: Observational [Patient Registry]
Study Design: Observational Model: Cohort
Time Perspective: Prospective
Target Follow-Up Duration: 1 Year
Official Title: TransFLUas: Transmission of Influenza Virus From Asymptomatic Healthcare Workers and Inpatients in the Acute Care Hospital Setting: A Prospective Study Over Two Consecutive Influenza Seasons

Resource links provided by NLM:


Further study details as provided by University of Zurich:

Primary Outcome Measures:
  • Secondary attack rate of asymptomatic or presymptomatic influenza among inpatients, among acute care workers and between inpatients and acute care HCW in an acute care hospital setting [ Time Frame: up to 6 months ]
    diagnosed by positive influenza PCR from flocked mid-turbinate nasal swab collected in symptomatic or asymptomatic individuals following face-to-face contact with an individual with symptomatic influenza infection on the day of contact.


Secondary Outcome Measures:
  • Secondary attack rate of symptomatic influenza among inpatients, among acute care workers and between inpatients and acute care HCW in an acute care hospital setting [ Time Frame: up to 6 months ]

    Secondary attack rate of symptomatic influenza among inpatients, among acute care workers and between inpatients and acute care HCW in an acute care hospital setting: as diagnosed by positive influenza PCR from flocked mid-turbinate nasal swab collected in symptomatic or asymptomatic individuals following face-to-face contact with an individual with symptomatic influenza infection on the day of contact. Transmissions will be considered 'proven' if confirmed by phylogenetic analyses. Specifically, we expect that whole-genome sequence analysis will demonstrate identical or almost identical influenza strains within transmission chains.

    Transmissions will be considered 'probable' if there is epidemiological evidence of face-to-face contact and identical strains have been identified in PCR but whole-genome sequencing was technically unsuccessful;


  • Proportion of asymptomatic and symptomatic inpatients with influenza infection upon hospital admission: as diagnosed by influenza polymerase chain reaction (PCR) from flocked mid-turbinate nasal swabs collected upon hospital admission [ Time Frame: up to 6 months ]
    diagnosed by influenza PCR from flocked mid-turbinate nasal swabs collected upon hospital admission

  • Incidence of asymptomatic (A5) and symptomatic (A6) nosocomial influenza in hospital inpatients, defined as the number of emerging influenza infections >72 hours after hospital admissions per 100 patient-days [ Time Frame: up to 6 months ]
    diagnosed by PCR from flocked mid-turbinate nasal swabs collected three times per week over the influenza season

  • Incidence of asymptomatic (A7) and symptomatic (A8) influenza in acute care hospital workers defined as the number of influenza infections per 100 HCW per influenza season [ Time Frame: up to 6 months ]
    diagnosed by influenza PCR from flocked mid-turbinate nasal swabs collected three times per week over the influenza season collected three times per week over the influenza season

  • Association of individual influenza symptoms with influenza transmission from subjects with symptomatic influenza infection [ Time Frame: up to 6 months ]
    Association of individual influenza symptoms with influenza transmission from subjects with symptomatic influenza infection

  • Influenza-attributable mortality in inpatients, expressed as infection-fatality rate, i.e. number of deaths among those infected [ Time Frame: up to 6 months ]
    number of deaths among those infected

  • Absenteeism: as defined by total number of days absent from work due to PCR-proven influenza divided by total number of days due to work in HCW [ Time Frame: up to 6 months ]
    Absenteeism: as defined by total number of days absent from work due to PCR-proven influenza divided by total number of days due to work in HCW;

  • Presenteeism: as defined by total number of days with symptoms of influenza present at work divided by total number of days due to work in HCW with PCR-proven influenza infection [ Time Frame: up to 6 months ]
    Presenteeism: as defined by total number of days with symptoms of influenza present at work divided by total number of days due to work in HCW with PCR-proven influenza infection;

  • Compliance with hand hygiene recommendations and cough etiquette (including barrier precautions) in HCW according to repeated observations [ Time Frame: up to 6 months ]
    Compliance with hand hygiene recommendations and cough etiquette (including barrier precautions) in HCW according to repeated observations;

  • Association of patient and HCW characteristics, including receipt of influenza vaccine, with asymptomatic viral shedding, as compared to symptomatic shedding [ Time Frame: up to 6 months ]
    Association of patient and HCW characteristics, including receipt of influenza vaccine, with asymptomatic viral shedding, as compared to symptomatic shedding;

  • Association between viral load and asymptomatic or symptomatic transmission based on quantification of viral shedding according to cycle threshold (Ct) values from PCR [ Time Frame: up to 6 months ]
    defined as the number of cycles required for the fluorescent signal to cross the threshold (i.e. exceeds background level).


Biospecimen Retention:   Samples With DNA

Virological analyses

  • Influenza A and B PCR from nasal swabs
  • Whole genome sequencing of positive swabs

Enrollment: 700
Study Start Date: January 2016
Study Completion Date: June 2017
Primary Completion Date: June 2017 (Final data collection date for primary outcome measure)
Groups/Cohorts Assigned Interventions
surveillance cohort
Flocked mid-turbinate nasal swabs for influenza PCR will be collected from study participants daily
Other: Influenza

Detailed Description:

The epidemiology and transmission dynamics of influenza in hospitals are only poorly understood, particularly with respect to subjects without symptoms of influenza infection (e.g. without fever, cough, sore throat, nasal congestion, weakness, headache, loss of appetite, or myalgia). Knowledge about whether asymptomatic subjects are able to transmit influenza is of major importance. If they do transmit influenza, vaccination of patients and healthcare workers (HCW) before start of the influenza season, the permanent use of masks by HCW during influenza season, and quarantine for previously exposed inpatients may be the only available measures to reduce the number of influenza transmission events from asymptomatic subjects in acute care hospitals.

The investigators' key aim is therefore to define whether exposure to asymptomatic subjects with influenza infection constitutes a risk for influenza transmission in an acute care hospital setting through active, prospective surveillance.

The investigators' secondary aims are to describe the prevalence of community-acquired symptomatic and asymptomatic influenza upon hospital admission and the incidence of asymptomatic and symptomatic nosocomial influenza among inpatients; to assess transmission dynamics of symptomatic influenza infection in acute care; and to study the incidence of asymptomatic and symptomatic influenza, absenteeism (i.e. being absent from work due to influenza), presenteeism (i.e. being present at work despite influenza infection) associated with influenza, and compliance with infection control recommendations to prevent spread of influenza in acute care HCW.

The investigators plan to enroll 1,260 inpatients and 180 HCW from medical wards at the University Hospital Zurich in a prospective study over two consecutive influenza seasons in order to detect at least one transmission event from an asymptomatic individual shedding influenza virus. Flocked mid-turbinate nasal swabs will be collected daily from consenting inpatients starting from day of admission until two days after discharge and from HCW over the influenza (winter) season and analyzed for influenza A and B using polymerase chain reaction. Simultaneously, signs and symptoms of influenza infection (including cough, sore throat, fever >37.8°C, nasal congestion, weakness, headache, loss of appetite or myalgia) as well as contact patterns between inpatients and HCW will be recorded. Reconstruction of influenza transmission chains will be based on phylogenetic analyses derived from next-generation sequence data and epidemiological contact tracing.

  Eligibility

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Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population
This project is a prospective study following patients in medical wards and acute care HCW (including nursing staff (nurses and assistant nurses), physiotherapists, house staff with direct patient contact and medical doctors (clinical fellows) working on the same wards at the University Hospital Zurich. Inpatients and HCW will be recruited from general medical and infectious diseases wards, pulmonology wards, hematology wards and from the stem cell transplant unit. All HCW and inpatients on the ward under surveillance are eligible for the study
Criteria

Inclusion Criteria:

  • 18 or more years of age;
  • Available for follow-up during the study period;
  • If a HCW: employed full- or part-time (≥50% full-time equivalent);
  • Understand the study, agree to its provisions, and give written informed consent (as documented by signature).

Exclusion Criteria:

  • If a HCW: planning to spend more than two consecutive weeks outside of Switzerland during the winter study period (November 1st to April 31st);
  • If a HCW: planning to take leave from work for more than two consecutive weeks during the winter study period (e.g. maternity or medical leave);
  • Inability to follow the procedures of the study, e.g. due to language problems, psychological disorders or dementia of the subject;
  • Known or suspected non-compliance.
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02478905


Locations
Switzerland
University Hospital Zurich
Zurich, Switzerland
Sponsors and Collaborators
University of Zurich
Schweizerischer Nationalfonds
Investigators
Principal Investigator: Stefan Kuster, MD Division of Infectious Diseases and Hospital Epidemiology
  More Information

Responsible Party: University of Zurich
ClinicalTrials.gov Identifier: NCT02478905     History of Changes
Other Study ID Numbers: KEK-ZH-Nr. 2015-0228
First Submitted: June 5, 2015
First Posted: June 23, 2015
Last Update Posted: October 31, 2017
Last Verified: October 2017

Additional relevant MeSH terms:
Influenza, Human
Orthomyxoviridae Infections
RNA Virus Infections
Virus Diseases
Respiratory Tract Infections
Respiratory Tract Diseases