Influenza Virus Infection Transmission in HumansEMITNCT01769430

Evaluating Modes of Influenza Transmission Observational Study of Community Acquired Influenza

An observational study of Influenza Virus Infection Transmission in Humans, run by University of Maryland, College Park at 1 site in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

Who is it for?: Ages 10 years and older
Conditions the study is for: Influenza Virus Infection Transmission in Humans
How many people: 178 participants
Where: 1 siteUnited States
Study dates: Dec 2012to Mar 2013
Phase: Observational
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 10 years and older
All sexes
No healthy volunteers
Child, Adult, Older adult

Study population: Students, faculty, and staff at the University of Maryland College Park and residents of the surrounding communities

Who may be able to join

Presence of symptomatic respiratory infection or other evidence of respiratory infection:
During the influenza season, subjects will be enrolled if they have
influenza-like illness (symptoms of fever and either cough or sore throat) and either
a positive point of care rapid test for influenza infection or
objectively documented fever in the setting of a documented local influenza outbreak (presence of rapid test or PCR confirmed cases).
Onset within the previous 48 hours
Prior to onset of influenza season and if we have not achieved enrollment of our target population by the end of flu season, we will enroll subjects with cough, coryza (stuffy runny nose, sore throat, sneezing), and malaise (fatigue) characteristic of the 'common cold' often resulting from Human Rhinovirus, RSV, parainfluenza, and to some extent influenza virus.

Who cannot join

Trial locations and contacts

1 site in 1 country.

United States1 site

University of Maryland School of Public Health
College Park, Maryland, 20742

Other trials in United States

About this study

Official title: Evaluating Modes of Influenza Transmission Work Package 1: Observational Study of Community Acquired Influenza

The recent swine origin influenza pandemic (2009), new emergence of swine origin H3N2v, and delayed availability of vaccine for these agents highlight the need to test and optimize public health intervention strategies to reduce transmission of influenza. We will use a new technology for biological particle collection (U.S. Provisional Patent Application No. 61/162,395, McDevitt et al., Aerosol Sci Technol 2013) to make fundamental observations on infectious respiratory droplets in a study of up to 200 naturally occurring seasonal influenza cases. We will collect respiratory droplets shed by participants while breathing normally, talking, and spontaneously coughing. We will characterize the size distribution of droplets containing infectious virus. We will use these basic data to examine the roles of large and small respiratory droplets and examine how the interaction of host factors and virus type impact the shedding of infectious respiratory droplets. Subjects will be recruited through a web based respiratory illness surveillance system, health clinics and advertisement in the campus community. Sitting in the collection booth will not create additional discomfort or risk for volunteers already suffering from influenza infection. We will recruit up to 1000 persons with symptoms of acute respiratory illness for screening with collection of nasopharyngeal swabs and questionnaire. From among those screened, we will recruit 250 to give exhaled breath samples, and ask 50 people with influenza to return for follow up exhaled breath samples on up to two subsequent days. We hypothesize that (1) fine aerosols (<5 microns in aerodynamic diameter) will contain more viral copies than coarse aerosol particles (>= 5 microns) (2) fine aerosols will contain culturable virus indicating that the fine aerosols are infectious, (3) aerosol shedding will correlate with virus load measured by swabs, (4) presence of active cough during sampling will be associated with increased aerosol shedding, (5) clinical symptoms and signs, including fever can be used to predict viral aerosol shedding.

Read the detailed description

This study is a follow-on to earlier projects funded by the US Centers for Disease Control and Prevention (CDC) and the National Institute for Allergy and Infectious Diseases (NIAID) that developed the sampler and studied the impact of surgical masks on reducing viral aerosol release by persons infected with influenza virus. The funding organizations have no direct control over the study design, execution, or reporting and no access to identifiable human data. The CDC IRB has determined that the CDC is not engaged in human subjects research in this cooperative agreement.

Hypotheses:

Fine particle aerosols will contain greater numbers of viral copies than will coarse aerosol particles.
Clinical symptoms and signs, including fever can be used to predict viral aerosol shedding
Fine aerosols will contain culturable virus indicating that the fine aerosols are infectious
Aerosol shedding will correlate with virus load measured by nasopharyngeal and throat swabs
Presence of active cough during sampling will be associated with increased aerosol shedding with a stronger correlation to be found with coarse than fine particle virus aerosols

Conditions: Influenza Virus Infection Transmission in Humans
Being tested: Observational Study of influenza aerosol shedding -- No Intervention
Keywords: influenza virus, aerosol transmission, contact transmission, large droplet transmission, airborne infection

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Observational Study of influenza aerosol shedding -- No InterventionOther
No intervention -- observational study only

Study groups in NCT01769430
Study group	Role	What they receive
Community acquired respiratory infection		Measurement of exhaled breath aerosol Receives: Other: Observational Study of influenza aerosol shedding -- No Intervention

What is being measured

The primary outcome is the main question the study is designed to answer.

Viral Copy Number in 30-minute Exhaled Breath Sample
Total viral RNA copies detected in breath aerosol exhaled during a 30-minute sample collection. Participants sit for 30 minutes with face inside the cone/funnel of the Gesundheit-II (G-II) human bioaerosol collector (https://doi.org/10.1080/02786826.2012.762973) collecting air at 130 L/min. Particles in air are concentrated into a small volume of buffer. The copies per mL of buffer is measured by PCR and corrected to the total amount collected per 30-min sample. See publication in the Proceedings of the National Academy of Sciences (https://doi.org/10.1073/pnas.1716561115) and PLoS Pathogens (https://doi.org/10.1371/journal.ppat.1003205) for more details.
Measured: Daily measurements on days 1 through 3 post onset of symptoms (each person contributed 1 to a max of 3 samples). Reported values are the geometric mean over all samples and persons.
Total Fine Aerosol Infectious Influenza Virus in 30-minute Exhaled Breath Sample
Fluorescent Focus Assay detection of infectious influenza virus in Fine Particle (≤5 µm) aerosol reported as fluorescent focus units (FFU) per 30-minute breath sample. Aerosol samples were collected at 130 L/min for 30 minutes by an aerosol sampler that concentrated the aerosol in a small volume of liquid. The FFU/ml were multiplied by the volume of liquid in the final concentrate sample to obtain the total infectious particles per 30-minute sample. This outcome was peer reviewed and published in the Proceedings of the National Academy of Sciences.
Measured: Daily measurements on days 1 through 3 post onset of symptoms (each person contributed 1 to a max of 3 samples). Reported values are the geometric mean over all samples and persons.

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

Dec 2012Mar 2013

First posted16 Jan 2013 (estimated)
Study startDec 2012
Primary completionMar 2013
Study completionMar 2013

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (4)Papers the sponsor has linked to this study.
Other trials for Influenza Virus Infection Transmission in HumansStudies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Observational
Observational model: Case only
Time perspective: Cross-sectional
Enrolment: 178 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT01769430
Sponsor's protocol ID: 017086-001
Other IDs: 1U01IP000497, 3U01CI000446, RC1AI086900
Acronym: EMIT
Status last verified: Apr 2025
First submitted: 14 Jan 2013
Last updated: 25 Apr 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
Individual data sharing: Yes: The study data for natural infections are available upon request. All analysis scripts and readme files required to reproduce analyses are available at https://gitlab.com/jacob bueno /natur al\_vs\_ artif icial\_infection

Publications

Fabian P, McDevitt JJ, DeHaan WH, Fung RO, Cowling BJ, Chan KH, Leung GM, Milton DK. Influenza virus in human exhaled breath: an observational study. PLoS One. 2008 Jul 16;3(7):e2691. doi: 10.1371/journal.pone.0002691.
PubMed 18628983
Milton DK, Fabian MP, Cowling BJ, Grantham ML, McDevitt JJ. Influenza virus aerosols in human exhaled breath: particle size, culturability, and effect of surgical masks. PLoS Pathog. 2013 Mar;9(3):e1003205. doi: 10.1371/journal.ppat.1003205. Epub 2013 Mar 7.
PubMed 23505369
McDevitt JJ, Koutrakis P, Ferguson ST, Wolfson JM, Fabian MP, Martins M, Pantelic J, Milton DK. Development and Performance Evaluation of an Exhaled-Breath Bioaerosol Collector for Influenza Virus. Aerosol Sci Technol. 2013 Jan 1;47(4):444-451. doi: 10.1080/02786826.2012.762973. Epub 2013 Jan 25.
PubMed 23418400
Yan J, Grantham M, Pantelic J, Bueno de Mesquita PJ, Albert B, Liu F, Ehrman S, Milton DK; EMIT Consortium. Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community. Proc Natl Acad Sci U S A. 2018 Jan 30;115(5):1081-1086. doi: 10.1073/pnas.1716561115. Epub 2018 Jan 18.
PubMed 29348203

Study at a glance

From the registry record, last updated by the sponsor on 25 Apr 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Evaluating Modes of Influenza Transmission Work Package 1: Observational Study of Community Acquired Influenza
ClinicalTrials.gov ID: NCT01769430
Acronym / sponsor ID: EMIT / 017086-001
Conditions: Influenza Virus Infection Transmission in Humans
Keywords: influenza virus, aerosol transmission, contact transmission, large droplet transmission, airborne infection
Study type: Observational
Recruitment status: Completed
Enrolment: 178 participants (actual)
Lead sponsor: University of Maryland, College ParkUniversity, hospital or other
Collaborators: Centers for Disease Control and Prevention, National Institute of Allergy and Infectious Diseases (NIAID)
Study start: Dec 2012
Primary completion: Mar 2013 (actual)
Study completion: Mar 2013 (actual)
First posted: 16 Jan 2013 (estimated)
Results: Posted 25 Apr 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Hypotheses:

Fine particle aerosols will contain greater numbers of viral copies than will coarse aerosol particles.
Clinical symptoms and signs, including fever can be used to predict viral aerosol shedding
Fine aerosols will contain culturable virus indicating that the fine aerosols are infectious
Aerosol shedding will correlate with virus load measured by nasopharyngeal and throat swabs
Presence of active cough during sampling will be associated with increased aerosol shedding with a stronger correlation to be found with coarse than fine particle virus aerosols

Study design

Observational model: Case only
Time perspective: Cross-sectional
Number of arms: 1

Arm	Type	Receives
Community acquired respiratory infection	–	Other: Observational Study of influenza aerosol shedding -- No InterventionMeasurement of exhaled breath aerosol

Who may qualify

Ages: 10 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Child, Adult, Older adult
Study population: Students, faculty, and staff at the University of Maryland College Park and residents of the surrounding communities

Key inclusion criteria (7 listed)

Presence of symptomatic respiratory infection or other evidence of respiratory infection:

Key exclusion criteria (1 listed)

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Observational Study of influenza aerosol shedding -- No InterventionNo intervention -- observational study only	Other	Community acquired respiratory infection

Primary outcome

Viral Copy Number in 30-minute Exhaled Breath Sample
Time frame: Daily measurements on days 1 through 3 post onset of symptoms (each person contributed 1 to a max of 3 samples). Reported values are the geometric mean over all samples and persons.
Total viral RNA copies detected in breath aerosol exhaled during a 30-minute sample collection. Participants sit for 30 minutes with face inside the cone/funnel of the Gesundheit-II (G-II) human bioaerosol collector (https://doi.org/10.1080/02786826.2012.762973) collecting air at 130 L/min. Particles in air are concentrated into a small volume of buffer. The copies per mL of buffer is measured by PCR and corrected to the total amount collected per 30-min sample. See publication in the Proceedings of the National Academy of Sciences (https://doi.org/10.1073/pnas.1716561115) and PLoS Pathogens (https://doi.org/10.1371/journal.ppat.1003205) for more details.
Total Fine Aerosol Infectious Influenza Virus in 30-minute Exhaled Breath Sample
Time frame: Daily measurements on days 1 through 3 post onset of symptoms (each person contributed 1 to a max of 3 samples). Reported values are the geometric mean over all samples and persons.
Fluorescent Focus Assay detection of infectious influenza virus in Fine Particle (≤5 µm) aerosol reported as fluorescent focus units (FFU) per 30-minute breath sample. Aerosol samples were collected at 130 L/min for 30 minutes by an aerosol sampler that concentrated the aerosol in a small volume of liquid. The FFU/ml were multiplied by the volume of liquid in the final concentrate sample to obtain the total infectious particles per 30-minute sample. This outcome was peer reviewed and published in the Proceedings of the National Academy of Sciences.

Results and safety

Results posted to the registry on 25 Apr 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
Symptomatic Influenza Virus Infection	178	178

Primary outcome: Viral Copy Number in 30-minute Exhaled Breath Sample

Time frame: Daily measurements on days 1 through 3 post onset of symptoms (each person contributed 1 to a max of 3 samples). Reported values are the geometric mean over all samples and persons.. Geometric mean (Standard Deviation). Unit: Fine aerosol RNA copy number

Measure	Community Acquired Respiratory Infection n = 178
Fine aerosol RNA copy number, Total copies per 30-minute breath sample	38,000 (13)
Coarse aerosol RNA copy number, Total per 30-minute breath sample	12,000 (14)

Population analysed: All cases meeting enrollment criteria

Primary outcome: Total Fine Aerosol Infectious Influenza Virus in 30-minute Exhaled Breath Sample

Measure	Community Acquired Respiratory Infection n = 142
Value	41 (30)

Population analysed: Participants with complete data

Adverse events

Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
Observational Study	0 of 178 (0%)	0 of 178 (0%)	0 of 178

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 25 Apr 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Background: PubMed 18628983Fabian P, McDevitt JJ, DeHaan WH, Fung RO, Cowling BJ, Chan KH, Leung GM, Milton DK. Influenza virus in human exhaled breath: an observational study. PLoS One. 2008 Jul 16;3(7):e2691. doi: 10.1371/journal.pone.0002691.
Background: PubMed 23505369Milton DK, Fabian MP, Cowling BJ, Grantham ML, McDevitt JJ. Influenza virus aerosols in human exhaled breath: particle size, culturability, and effect of surgical masks. PLoS Pathog. 2013 Mar;9(3):e1003205. doi: 10.1371/journal.ppat.1003205. Epub 2013 Mar 7.
Background: PubMed 23418400McDevitt JJ, Koutrakis P, Ferguson ST, Wolfson JM, Fabian MP, Martins M, Pantelic J, Milton DK. Development and Performance Evaluation of an Exhaled-Breath Bioaerosol Collector for Influenza Virus. Aerosol Sci Technol. 2013 Jan 1;47(4):444-451. doi: 10.1080/02786826.2012.762973. Epub 2013 Jan 25.
Results publication: PubMed 29348203Yan J, Grantham M, Pantelic J, Bueno de Mesquita PJ, Albert B, Liu F, Ehrman S, Milton DK; EMIT Consortium. Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community. Proc Natl Acad Sci U S A. 2018 Jan 30;115(5):1081-1086. doi: 10.1073/pnas.1716561115. Epub 2018 Jan 18.
Individual participant dataSharing planned: Yes. The study data for natural infections are available upon request. All analysis scripts and readme files required to reproduce analyses are available at https://gitlab.com/jacob bueno /natur al_vs_ artif icial_infection

Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Donald K Milton, MD, DrPH principal investigator

University of Maryland

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

An observational study of Influenza Virus Infection Transmission in Humans, run by University of Maryland, College Park at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 7 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 25 Apr 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

Yes. Results are posted in the registry (first posted 25 Apr 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Viral Copy Number in 30-minute Exhaled Breath Sample (time frame: Daily measurements on days 1 through 3 post onset of symptoms (each person contributed 1 to a max of 3 samples). Reported values are the geometric mean over all samples and persons.). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT01769430, which also lists 4 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 25 Apr 2025; AzTrials last refreshed its copy on 7 Nov 2026.