Air Filtration + Ventilation for COVID-19

Enrolling by invitation at 1 trial location

Age: Any Age

Sex: Any

Trial Phase: Academic

Sponsor: Stanford University

Disqualifiers: Index case positive over 2 days, Half household infected, Fewer than 3 contacts, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 7

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial tests whether box-fans with special filters and improved home ventilation can stop COVID-19 from spreading within a household. Families will either receive these filtration fans (a type of air filtration device) along with advice on improving airflow or follow standard guidance without fans. The study aims to determine if these measures can prevent others in the home from catching the virus. It suits families living together where at least one person has recently tested positive for COVID-19, and there are at least three other members in the household. As an unphased trial, this study offers families a chance to contribute to important research on preventing COVID-19 spread at home.

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications.

What prior data suggests that this intervention is safe for reducing COVID-19 spread in homes?

Research has shown that air cleaners and HVAC filters can reduce airborne germs, including the virus that causes COVID-19, thereby lowering the risk of airborne diseases. Studies have found that even homemade air filters can improve airflow and reduce exposure to harmful particles. Portable air filters are easy to use and play a crucial role in reducing the risk of spreading infections indoors.

No known negative effects arise from using these air filters. They clean the air without adding chemicals or substances, making them generally safe for home use to help reduce the spread of COVID-19. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the trial exploring air filtration and improved ventilation for COVID-19 because it focuses on a non-pharmaceutical approach to reducing virus spread within homes. Unlike standard treatments that often involve medications or vaccines, this method uses filtration fan units to clean the air, combined with enhanced ventilation strategies. This approach aims to directly lower the concentration of viral particles in indoor air, potentially reducing secondary transmission without relying on drugs or complex medical interventions. The trial could offer a simple, accessible way for families to protect themselves, especially in settings where medical options are limited or vaccination rates are low.

What evidence suggests that this trial's interventions could be effective for reducing COVID-19 spread in homes?

Research has shown that air cleaners and HVAC filters, like those in the filtration fans used in this trial, can reduce airborne germs, including viruses. Participants in the intervention arm of this trial will receive filtration fans for their homes. Studies have found that portable air cleaners can remove aerosols five times faster in controlled settings. One study discovered that DIY air cleaners reduced aerosol exposure by up to 73%, especially when increasing the fan's airflow and filter thickness. Real-world data from hospitals also show that portable air filters effectively remove particles of the virus that causes COVID-19 from the air. These findings suggest that using filtration fans at home might help reduce the spread of COVID-19 by cleaning the air of infectious particles. ^{1 6 7 8 9}

Who Is on the Research Team?

Abraar Karan, MD

Principal Investigator

Stanford University

Yvonne Maldonado, MD

Principal Investigator

Stanford University

Are You a Good Fit for This Trial?

This trial is for households with a confirmed case of COVID-19 and at least three other people living together. Eligible homes must not have had the positive test result more than two days ago, expect most members to be present over the next week, and can't already have half or more members likely infected.

Inclusion Criteria

There are at least three other people living in the same house as the person being studied.

You live with others in the same house or apartment, not in a separate room.

Exclusion Criteria

If household has fewer than 3 contacts interested in participating in the study

If the positive test result was more than 2 days ago

If more than half of the people living in your home are believed to already have the infection.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1 week

Intervention

Families receive filtration fans and ventilation advice; baseline testing conducted

7 days

Day 0-1 baseline testing, Day 3-4 follow-up

Follow-up

Participants are monitored for secondary transmission and CO2 levels

7 days

Day 7 testing for secondary transmission

What Are the Treatments Tested in This Trial?

Interventions

• Filtration Fan
• Mid-week phone call
• Safe-home pamphlet

Trial Overview The study tests if using box-fans with high-efficiency filters alongside guidance on improving home ventilation can prevent COVID-19 from spreading to others in the same household as someone who's infected.

How Is the Trial Designed?

Group I: Intervention Experimental Treatment 3 Interventions

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.

Group II: Control Active Control 1 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.

Who Is Running the Clinical Trial?

Stanford University

Lead Sponsor

Trials

2,527

Recruited

17,430,000+

National Institute of Allergy and Infectious Diseases (NIAID)

Collaborator

Trials

3,361

Recruited

5,516,000+

Published Research Related to This Trial

A study demonstrated that HEPA filters can effectively remove airborne SARS-CoV-2, achieving capture ratios of 85.38%, 96.03%, and over 99.97% at different ventilation volumes, indicating their potential for infection control in indoor environments.

The performance of HEPA filters coated with an antiviral agent was found to be comparable to that of conventional HEPA filters, suggesting that both types are effective in reducing the spread of COVID-19 in the air.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effectiveness of HEPA Filters at Removing Infectious SARS-CoV-2 from the Air. Ueki, H., Ujie, M., Komori, Y., et al.[2022]

Citations

1. epa.gov epa.gov/indoor-air-quality-iaq/air-cleaners-hvac-filters-and-coronavirus-covid-19

Air Cleaners, HVAC Filters, and Coronavirus (COVID-19) When used properly, air cleaners and HVAC filters can help reduce airborne contaminants including viruses in a building or small space.

2. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC8481008/

Effectiveness of portable air filtration on reducing indoor ... Portable air cleaning devices were very effective for removal of aerosols. The aerosols were cleared five times faster in a small control room with portable ...

3. frontiersin.org frontiersin.org/journals/environmental-health/articles/10.3389/fenvh.2025.1548272/full

The effectiveness of air-cleaning technologies against ... This systematic review aims to assess the effectiveness of air-cleaning methods in preventing COVID-19 transmission in health facilities.

4. sciencedirect.com sciencedirect.com/science/article/pii/S0360132322011507

Efficacy of Do-It-Yourself air filtration units in reducing ... In our study, two DIY air cleaners reduced aerosol exposure up to 73%. Increasing fan airflow and filter depth significantly improved performance.

5. nature.com nature.com/articles/d41586-021-02669-2

Real-world data show that filters clean COVID-causing ... Research at a hospital swamped by people with COVID-19 has confirmed that portable air filters effectively remove SARS-CoV-2 particles from the air.

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC9759459/

Efficacy of Do-It-Yourself air filtration units in reducing ... Increasing the number of filters, filter thickness, and fan airflow significantly enhanced the air change rate, which resulted in exposure reductions of up to ...

7. epa.gov epa.gov/indoor-air-quality-iaq/indoor-air-homes-and-coronavirus-covid-19

Indoor Air in Homes and Coronavirus (COVID-19) Ensuring proper ventilation with outside air can help reduce indoor airborne contaminants, including SARS-CoV-2, the virus that causes COVID-19, and other ...

8. cdc.gov cdc.gov/covid/communication/improve-air-home.html

Improving the Air in Your Home | COVID-19 Filtering the air helps stop COVID-19​​ Turn the thermostat fan to "on" instead of "auto." Some heating and air conditioning systems have filters ...

9. sciencedirect.com sciencedirect.com/science/article/pii/S1876034124003848

Science tells us that portable air filters reduce infection risk. ... PAFs are an important tool to help reduce the risk of transmission of airborne infectious diseases. Moreover, PAFs are relatively simple to use.