Reduction in COVID-19 Infection Using Surgical Facial Masks Outside the Healthcare System
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ClinicalTrials.gov Identifier: NCT04337541 |
Recruitment Status :
Completed
First Posted : April 7, 2020
Last Update Posted : August 3, 2020
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In the current COVID-19 pandemic with coronavirus, SARS-COV2, the Danish Health Authorities recommend using facial masks in the health care system when handling patients presumed or proven to be infected with the virus. However, the use of facial masks outside the health care system is not recommended by the Danish Health Authorities. Here, Health Authorities in other countries have different recommendations for the use of facial masks.
Challenges when using facial masks outside the health care system include wearing the mask consistently, an efficacy of the mask of app. 8 hours necessitating a change of mask throughout the day, and that it is not sufficiently tight enough to safely keep the virus out. Moreover, the eyes (mucous membrane) remain exposed. Compliance could also be another challenge.
SARS-COV2 is assumed to primarily enter the body via the mouth through respiratory droplets - or possibly through inhalation of aerosol containing the virus. From the mouth the virus is assumed to spread to the airways and the gastro-intestinal tract. SARS-COV2 is also known to be transmitted via physical contact, helped along by the fact that the virus can survive on surfaces for at least 72 hours. Touching such a contaminated surface can transfer the virus to the mouth via the hand - and thus lead to infection of the person.
Facial masks are expected to protect against viral infection in two ways;
- By reducing the risk of getting the virus in via the mouth or nose via respiratory droplets or aerosol
- By reducing the transfer from virus-contaminated hands to the mouth or nose
Hypothesis The use of surgical facial masks outside the hospital will reduce the frequency of COVID-19 infection.
All participants will follow authority recommendations and be randomized to either wear facial masks or not. The participants will be screened for antibodies at study start and study end. They will perform swab-test if they experience symptoms during the study as well as the end of study.
Condition or disease | Intervention/treatment | Phase |
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COVID-19 | Other: Surgical facial mask | Not Applicable |

Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 6000 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Intervention Model Description: | The participants recruited are people working outside of their home, who have not previously been infected with COVID-19 and who do not wear facial masks (e.g. healthcare personnel) when working. They will be randomized for
Participants will be instructed in using the facial mask consistently when outside their home (and at home when receiving visits from others. The instruction is given in writing and via an instruction video. The participants will be contacted once weekly to optimize compliance. It will be registered if the participants are diagnosed with COVID-19. Participants will perform antibody screening at study start and end. Participants, who are not tested positive for COVID-19 in the study period will perform a swab self-test if experiencing symptoms or when the study ends (instruction video). |
Masking: | None (Open Label) |
Primary Purpose: | Prevention |
Official Title: | Reduction in COVID-19 Infection Using Surgical Facial Masks Outside the Healthcare System |
Actual Study Start Date : | April 2, 2020 |
Actual Primary Completion Date : | June 2, 2020 |
Actual Study Completion Date : | June 2, 2020 |

Arm | Intervention/treatment |
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No Intervention: Normal recommendations, no mask
Normal behavior according to the authority's recommendations or
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Experimental: Normal recommendations AND mask
Normal behavior according to the authority's recommendations AND use of facial masks
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Other: Surgical facial mask
Participants will follow normal Authority recommendations AND wear mask outside their homes, or when receiving visits in their home. |
- The primary endpoint is the difference in SARS-CoV-2 infection between the two groups after 1 months and is a combined endpoint consisting of primary outcome components 1, 2 and/or 3: [ Time Frame: 1 month ]Component 1 of primary endpoint: Positive oropharyngeal/nasal swab with SARS-CoV-2 (PCR) and/or
- The primary endpoint is the difference in SARS-CoV-2 infection between the two groups after 1 months and is a combined endpoint consisting of primary outcome components 1, 2 and/or 3: [ Time Frame: 1 month ]Component 2 of primary endpoint: Antibody test; Development of positive SARS-CoV-2 antibody test (IgM and/or IgG) during the study period and/or
- The primary endpoint is the difference in SARS-CoV-2 infection between the two groups after 1 months and is a combined endpoint consisting of primary outcome components 1, 2 and/or 3: [ Time Frame: 1 month ]Component 3 of primary endpoint: SARS-CoV-2 infection diagnosed in a hospital/health care facility
- Positive oropharyngeal/nasal swab (PCR); [ Time Frame: 1 month ]Para-influenza-virus type 1, Para-influenza-virus type 2, Human coronavirus 229E, Human coronavirus OC43, Human coronavirus NL63, Human coronavirus HKU1, Respiratory Syncytial-Virus A, Respiratory Syncytial-Virus B, Influenza A virus or Influenza B virus
- Positive oropharyngeal/nasal swab (PCR); [ Time Frame: 1 month ]SAR-CoV-2, Para-influenza-virus type 1, Para-influenza-virus type 2, Human coronavirus 229E, Human coronavirus OC43, Human coronavirus NL63, Human coronavirus HKU1, Respiratory Syncytial-Virus A, Respiratory Syncytial-Virus B, Influenza A virus or Influenza B virus
- Difference between the two study groups [ Time Frame: 1 month ]Returned swabs
- Discribtion of the face mask users psycological aspects of wearing face masks [ Time Frame: 1 month ]Psychological aspects of face mask wearing in the community
- Costs associated with wearing vs not wearing face masks [ Time Frame: 1 month ]Cost-effectiveness analyses on the use of surgical face masks
- Differences in the participants preferences [ Time Frame: 1 month ]Preference for self-conducted home swab vs. healthcare conducted swab at hospital or similar
- Difference between the two study groups [ Time Frame: 1 month ]Symptoms of COVID-19
- Difference between the two study groups with stratification between subgroups (age, gender, occupation, comorbidities) [ Time Frame: 1 month ]Self-assessed compliance with health authority guideline on hygiene
- Discribtion of the face mask users willingness to wear face masks [ Time Frame: 1 month ]Willingness to wear face masks in the future
- Healthcare diagnosed COVID-19 between study groups [ Time Frame: 1 month ]Healthcare diagnosed COVID-19 or identified SARS-CoV-2 infection as assessed by number of participants with antibodies against SARS-CoV-2, and/or positive maso/pharyngeal swab (PCR), mortality associated with COVID-19 and all cause mortality
- Hospital based diagnostics of bacteria between the two study groups [ Time Frame: 1 month ]Presence of bacteria: Mycoplasma pneumonia, Haemophilus influenza and Legionella pneumophila (to be obtained from registries when made available)
- Infection in the household between the two study groups [ Time Frame: 1 month ]Frequency of infected house-hold members between the two groups
- Sick leave among participants beteeen the two study groups [ Time Frame: 1 month ]Frequency of sick leave between the two groups (to be obtained from registries when made available)
- Predictors of primary outcome; age, gender, size of household, comorbidities, medications, social factors, occupation, mask compliance, compliance to general SARS-CoV-2 recommendations, hours outside home) [ Time Frame: 1 month ]Predictors of primary outcome or its components

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Ages Eligible for Study: | 18 Years and older (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria:
- Older than 18 years of age and without symptoms associated with corona-virus (or previously tested positive for corona).
- Participant is outside their home more than 3 hours a day. E.g.for work or for other activities among other people.
- Do not normally wear a facial mask for daily work (e.g. healthcare personnel)
Exclusion Criteria:
- Previously tested positive for corona-virus
- Wear facial mask for work

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): NCT04337541
Denmark | |
Rigshospitalet | |
Copenhagen, Denmark, 2100 |
Principal Investigator: | Henrik Ullum, Prof., DMSc | Rigshospitalet, Denmark | |
Principal Investigator: | Kasper Karmark Iversen, Prof., DMSc | Herlev Hospital | |
Principal Investigator: | Thomas Benfield, Prof., DMSc | Hvidovre University Hospital | |
Principal Investigator: | Christian Torp-Pedersen, Prof., DMSc | Nordsjællands Hospital |
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: | Henning Bundgaard, Professor of Cardiology, Consultant, MD, DMSc, Rigshospitalet, Denmark |
ClinicalTrials.gov Identifier: | NCT04337541 |
Other Study ID Numbers: |
2020-04-02 |
First Posted: | April 7, 2020 Key Record Dates |
Last Update Posted: | August 3, 2020 |
Last Verified: | July 2020 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | No |
Studies a U.S. FDA-regulated Device Product: | No |
Infection |