Trial Outcomes & Findings for Evaluating Modes of Influenza Transmission Observational Study of Community Acquired Influenza (NCT NCT01769430)

Last Updated: 2025-04-25

Results Overview

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.

Recruitment status

COMPLETED

Target enrollment

178 participants

Primary outcome timeframe

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.

Results posted on

2025-04-25

Participant Flow

Self reported ILI and influenza diagnosed by campus health center

must have fever measured by campus medical provider or by research clinic with a sore throat or cough, or a positive rapid antigen test for influenza A or B and must be within 3 days of onset of symptoms

Participant milestones

Participant milestones
Measure	Symptomatic Influenza Virus Infection Symptomatic influenza cases with either fever or a positive rapid antigen test.
Overall Study STARTED	178
Overall Study COMPLETED	178
Overall Study NOT COMPLETED	0

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

Evaluating Modes of Influenza Transmission Observational Study of Community Acquired Influenza

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Community Acquired Influenza Virus Infection n=178 Participants Volunteers with positive rapid antigen test or objectively measured fever with complaint of cough or sore throat during the influenza season.
Age, Continuous	21 years n=5 Participants
Sex: Female, Male Female	87 Participants n=5 Participants
Sex: Female, Male Male	91 Participants n=5 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	1 Participants n=5 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	177 Participants n=5 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants
Race (NIH/OMB) American Indian or Alaska Native	1 Participants n=5 Participants
Race (NIH/OMB) Asian	32 Participants n=5 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants
Race (NIH/OMB) Black or African American	12 Participants n=5 Participants
Race (NIH/OMB) White	109 Participants n=5 Participants
Race (NIH/OMB) More than one race	24 Participants n=5 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants
Region of Enrollment United States	178 participants n=5 Participants

PRIMARY outcome

Timeframe: 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.

Population: All cases meeting enrollment criteria

Outcome measures

Outcome measures
Measure	Community Acquired Respiratory Infection n=178 Participants Measurement of exhaled breath aerosol Observational Study of influenza aerosol shedding -- No Intervention: No intervention -- observational study only	Volunteers Nasally Inoculated With A/Wisconsin/2005 (H3N2) From ClinicalTrials.gov (number NCT01710111).
Viral Copy Number in 30-minute Exhaled Breath Sample Fine aerosol RNA copy number, Total copies per 30-minute breath sample	38,000 Fine aerosol RNA copy number Standard Deviation 13	—
Viral Copy Number in 30-minute Exhaled Breath Sample Coarse aerosol RNA copy number, Total per 30-minute breath sample	12,000 Fine aerosol RNA copy number Standard Deviation 14	—

PRIMARY outcome

Timeframe: 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.

Population: Participants with complete data

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.

Outcome measures

Outcome measures
Measure	Community Acquired Respiratory Infection n=142 Participants Measurement of exhaled breath aerosol Observational Study of influenza aerosol shedding -- No Intervention: No intervention -- observational study only	Volunteers Nasally Inoculated With A/Wisconsin/2005 (H3N2) From ClinicalTrials.gov (number NCT01710111).
Total Fine Aerosol Infectious Influenza Virus in 30-minute Exhaled Breath Sample	41 Total FFU/30-minute sample Standard Deviation 30	—

OTHER_PRE_SPECIFIED outcome

Timeframe: Maximal shedding during days 1-3 post onset of symptoms (natural infections) or days 1-4 post inoculation (nasally inoculated volunteers)

Population: Adults naturally infected with influenza A H3N2

We compared influenza A viral aerosol shedding from volunteers nasally inoculated with A/Wisconsin/2005 (H3N2) and college community adults naturally infected with influenza A/H3N2 (2012-2013), selected for influenza-like illness with objectively measured fever or a positive Quidel QuickVue A\&B test. Propensity scores were used to control for differences in symptom presentation observed between experimentally and naturally infected groups.

Outcome measures

Outcome measures
Measure	Community Acquired Respiratory Infection n=83 Participants Measurement of exhaled breath aerosol Observational Study of influenza aerosol shedding -- No Intervention: No intervention -- observational study only	Volunteers Nasally Inoculated With A/Wisconsin/2005 (H3N2) n=39 Participants From ClinicalTrials.gov (number NCT01710111).
Comparison of Exhaled Virus in Community Acquired and Experimental Infection	39000 Fine aerosol RNA copies/ 30-min sample Standard Deviation 15.12	5100 Fine aerosol RNA copies/ 30-min sample Standard Deviation 4.72

POST_HOC outcome

Timeframe: 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.

Population: Convenience subsample

A convenience subsample were tested for exhaled particle counts using an optical particle counter during research clinic visits as a postdoctoral exploratory investigation. No formal analysis was completed.

Outcome measures

Outcome data not reported

POST_HOC outcome

Timeframe: Within 3 days of onset of influenza like illness

Population: Postdoc left lab without completing write up of analysis due to lack of finding a correlation. Notes and data from 12 years ago are no longer easily accessible.

Exploratory analysis of impact of other respiratory present in nasopharyngeal swabs on extent of aerosol shedding.

Outcome measures

Outcome data not reported

Adverse Events

Observational Study

Serious events: 0 serious events

Other events: 0 other events

Deaths: 0 deaths

Serious adverse events

Adverse event data not reported

Other adverse events

Adverse event data not reported

Additional Information

Professor & Director PHAB Lab

University of Maryland, College Park

Phone: 424-246-8358

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place