Covid19NCT05777720
Cluster-Randomized Trial of Air Filtration and Ventilation to Reduce Covid19 Spread in Homes
A study testing Filtration Fan, Safe-home pamphlet and Mid-week phone call in people with Covid19, run by Stanford University at 2 sites in United States.
Trial summary
Investigators are evaluating whether an intervention consisting of box-fans with MERV 16 filters ("filtration fans") and recommendations for improving ventilation in the home can reduce secondary spread of Covid19 from an index case to susceptible contacts within the home. Read more about this study
- Who is it for?
- Any ageHealthy volunteers can take part
- Conditions the study is for
- Covid19
- What is being tested?
- Filtration Fan, Safe-home pamphlet and Mid-week phone call
- Type of treatment
- Medical device, Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 214 participants
- Where
- 2 sitesUnited States
- Study dates
- 30 Jan 2023to 30 Dec 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 Any age
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- Household members live in a shared space (apartment, home) with others (as opposed to renting single rooms in a shared space, for example)
- At least 3 other people live in the household aside from index case
Who cannot join
- If index case test positive day was over 2 days prior
- If half or more household members are thought to be infected already
- If household has fewer than 3 contacts interested in participating in the study
- If fewer than 3 contacts are expected to be present in the house for a majority of the following 7 days
Trial locations and contacts
2 sites in 1 country.
United States2 sites
San Mateo Medical Center
San Mateo, California, 94403
Stanford University Medical Center
Stanford, California, 94305
About this study
Official title: A Cluster-randomized Controlled Trial of Air Filtration and Ventilation Improvements to Reduce SARS CoV 2 Transmission Among Household Contacts
Investigators are evaluating whether an intervention consisting of box-fans with MERV 16 filters ("filtration fans") and recommendations for improving ventilation in the home can reduce secondary spread of Covid19 from an index case to susceptible contacts within the home.
- Conditions
- Covid19
- Being tested
- Filtration Fan, Safe-home pamphlet, Mid-week phone call
- Keywords
- ventilation, air filtration, Covid19, SARS CoV 2, household transmission
- Medical subject headings
- COVID-19, Respiratory Aspiration
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Filtration FanDevice
Investigators are using box fans with attached MERV16 filters, a design that has been tested and published in the scientific literature.
Safe-home pamphletBehavioural
The pamphlet has information on how the filtration fans work through visual images; and images of ventilation improvements in the home through opening windows.
Mid-week phone callBehavioural
On day 3-4 of the study, the study coordinator assigned to the house will call and check in regarding the filtration fan usage and remind families about the importance of filtration and ventilation.
| Study group | Role | What they receive |
|---|---|---|
| Control | No intervention | No intervention will be administered in this arm. Investigators will give families a CO2 monitor to measure average CO2 levels in the home. Investigators will provide a link to the basic CDC isolation guidelines which would be part of standard of care. Investigators will test family members at day 0-1 for baseline testing; and again on day 7 for assessing secondary transmission among susceptible contacts. |
| Intervention | Experimental | Families are provided with one filtration fan unit per room in their home (and one for the index case; if the family lives in a studio, they would receive 2 units). Investigators will advise families on ventilation improvements in their home. Investigators will provide an instructional pamphlet that describes how the fans work and the importance of ventilation. Investigators will follow-up on day 3-4 to check in and run through a checklist to ensure the fans are working and ventilation improvements are being attempted. Investigators will give families a CO2 monitor to measure average CO2 levels in the home. Investigators will test family members at day 0-1 for baseline testing; and again on day 7 for assessing secondary transmission among susceptible contacts. Receives: Device: Filtration Fan; Behavioral: Safe-home pamphlet; Behavioral: Mid-week phone call |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence of Covid19
Investigators will measure the incidence of Covid19 in susceptible contacts on day 7.
Measured: 7th day since enrollment in the trial
Secondary outcomes (2)
Incidence of new upper respiratory symptoms
Investigators will measure reported new upper respiratory symptoms in susceptible contacts.
Measured: 7th day since enrollment in the trial
Average CO2 levels
Investigators will measure 7 day average CO2 levels in the home (measured in parts per million)
Measured: 7 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Mar 2023
- Study start30 Jan 2023
- Primary completion30 Dec 2025
- Study completion30 Dec 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Covid19Studies of the same condition, open and under way.
- More trials run by Stanford UniversityThe sponsor's other registered studies.
- 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 214 participants (actual)
Sponsor and investigators
- Lead sponsor
- Stanford University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Abraar Karan, Stanford University
- Investigators
- Yvonne Maldonado, MD, Study director, Stanford UniversityAbraar Karan, MD, Principal investigator, Stanford University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05777720
- Sponsor's protocol ID
- 55479
- Other IDs
- 5T32AI052073-17
- Status last verified
- Feb 2026
- First submitted
- 18 Mar 2023
- Last updated
- 19 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 19 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Cluster-randomized Controlled Trial of Air Filtration and Ventilation Improvements to Reduce SARS CoV 2 Transmission Among Household Contacts
- ClinicalTrials.gov ID
- NCT05777720
- Acronym / sponsor ID
- 55479
- Conditions
- Covid19
- Keywords
- ventilation, air filtration, Covid19, SARS CoV 2, household transmission
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 214 participants (actual)
- Lead sponsor
- Stanford UniversityUniversity, hospital or other
- Collaborators
- National Institute of Allergy and Infectious Diseases (NIAID)
- Study start
- 30 Jan 2023 (actual)
- Primary completion
- 30 Dec 2025 (actual)
- Study completion
- 30 Dec 2025 (actual)
- First posted
- 21 Mar 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Investigators are evaluating whether an intervention consisting of box-fans with MERV 16 filters ("filtration fans") and recommendations for improving ventilation in the home can reduce secondary spread of Covid19 from an index case to susceptible contacts within the home.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Control | No intervention | –No intervention will be administered in this arm. Investigators will give families a CO2 monitor to measure average CO2 levels in the home. Investigators will provide a link to the basic CDC isolation guidelines which would be part of standard of care. Investigators will test family members at day 0-1 for baseline testing; and again on day 7 for assessing secondary transmission among susceptible contacts. |
| Intervention | Experimental | Device: Filtration Fan, Behavioral: Safe-home pamphlet, Behavioral: Mid-week phone callFamilies are provided with one filtration fan unit per room in their home (and one for the index case; if the family lives in a studio, they would receive 2 units). Investigators will advise families on ventilation improvements in their home. Investigators will provide an instructional pamphlet that describes how the fans work and the importance of ventilation. Investigators will follow-up on day 3-4 to check in and run through a checklist to ensure the fans are working and ventilation improvements are being attempted. Investigators will give families a CO2 monitor to measure average CO2 levels in the home. Investigators will test family members at day 0-1 for baseline testing; and again on day 7 for assessing secondary transmission among susceptible contacts. |
Who may qualify
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (2 listed)
- Household members live in a shared space (apartment, home) with others (as opposed to renting single rooms in a shared space, for example)
- At least 3 other people live in the household aside from index case
Key exclusion criteria (4 listed)
- If index case test positive day was over 2 days prior
- If half or more household members are thought to be infected already
- If household has fewer than 3 contacts interested in participating in the study
- If fewer than 3 contacts are expected to be present in the house for a majority of the following 7 days
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 |
|---|---|---|
| Filtration FanInvestigators are using box fans with attached MERV16 filters, a design that has been tested and published in the scientific literature. | Device | Intervention |
| Safe-home pamphletThe pamphlet has information on how the filtration fans work through visual images; and images of ventilation improvements in the home through opening windows. | Behavioural | Intervention |
| Mid-week phone callOn day 3-4 of the study, the study coordinator assigned to the house will call and check in regarding the filtration fan usage and remind families about the importance of filtration and ventilation. | Behavioural | Intervention |
Primary outcome
Incidence of Covid19
Time frame: 7th day since enrollment in the trial
Investigators will measure the incidence of Covid19 in susceptible contacts on day 7.
2 secondary outcomes
Incidence of new upper respiratory symptoms
Time frame: 7th day since enrollment in the trial
Average CO2 levels
Time frame: 7 days
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 19 Feb 2026.
- Individual participant dataSharing planned: No
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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.
Yvonne Maldonado, MD study director
Stanford University
Abraar Karan, MD principal investigator
Stanford University
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Filtration Fan, Safe-home pamphlet and Mid-week phone call in people with Covid19, run by Stanford University at 2 sites 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 2 inclusion and 4 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 19 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Incidence of Covid19 (time frame: 7th day since enrollment in the trial). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 19 Feb 2026.