COVID -19NCT07597889
Diagnostic Accuracy of 2 cm Versus 4 cm Insertion Depth for Nasal Swabs for SARS-CoV-2 (COVID-19) Rapid Antigen Testing-A Randomized Controlled Trial
A study testing 4 cm nasal swab - left nostril, 2 cm nasal swab in the left nostril and 4 cm nasal swab - right nostril in people with COVID -19, run by Copenhagen University Hospital, Rigshospitalet at 1 site in Denmark.
Trial summary
This study aims to compare the diagnostic accuracy of rapid antigen detection tests (RDTs) for SARS-CoV-2 using nasal swab insertion depths of 2 cm versus 4 cm. The study is an investigator-initiated, randomized clinical trial conducted at a public COVID-19 test center in Copenhagen, Denmark. Read more about this study
- Who is it for?
- Ages 16 years and olderHealthy volunteers can take part
- Conditions the study is for
- COVID -19
- What is being tested?
- 4 cm nasal swab - left nostril, 2 cm nasal swab in the left nostril and 4 cm nasal swab - right nostril
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 317 participants
- Where
- 1 siteDenmark
- Study dates
- 1 Feb 2023to 26 Feb 2023
- 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 16 years and older
- All sexes
- Healthy volunteers accepted
- Child, Adult, Older adult
Who may be able to join
- Citizens, aged 16 years or older, showing up for a SARS-CoV-2 RT-PCR test at Testcenter Valby in Copenhagen, Denmark
Who cannot join
- non-fluent in Danish
- citizens with nasopharyngeal or oropharyngeal anomalies (e.g. neck breathers with tracheostomy)
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Diagnostic Accuracy of 2 cm Versus 4 cm Insertion Depth for Nasal Swabs for SARS-CoV-2 Rapid Antigen Testing-A Randomized Controlled Trial
This study aims to compare the diagnostic accuracy of rapid antigen detection tests (RDTs) for SARS-CoV-2 using nasal swab insertion depths of 2 cm versus 4 cm.
The study is an investigator-initiated, randomized clinical trial conducted at a public COVID-19 test center in Copenhagen, Denmark.
Read more
Following enrollment, participants complete a questionnaire regarding symptoms and vaccination status.
Participants are randomized in a 1:1 ratio to one of two sampling sequences: either a 2 cm swab in the left nostril and a 4 cm swab in the right nostril, or vice versa. All participants undergo a healthcare worker-collected throat swab for RT-PCR analysis, which serves as the reference standard for SARS-CoV-2 infection.
- Conditions
- COVID -19
- Being tested
- 4 cm nasal swab - left nostril, 2 cm nasal swab in the left nostril, 4 cm nasal swab - right nostril, 2 cm nasal swab - right nostril
- Keywords
- covid-19
- Medical subject headings
- COVID-19
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
4 cm nasal swab - left nostrilDiagnostic test
a 4 cm nasal swab insertion in the left nostril
2 cm nasal swab in the left nostrilDiagnostic test
a 2 cm nasal swab insertion in the left nostril
4 cm nasal swab - right nostrilDiagnostic test
a 4 cm nasal swab insertion in the right nostril
2 cm nasal swab - right nostrilDiagnostic test
a 2 cm nasal swab insertion in the right nostril
| Study group | Role | What they receive |
|---|---|---|
| 2 cm nasal swab in the right nostril, and 4 cm nasal swab in the left nostril | Experimental | Not described Receives: Diagnostic Test: 4 cm nasal swab - left nostril; Diagnostic Test: 2 cm nasal swab - right nostril |
| 4 cm nasal swab in the right nostril, and 2 cm nasal swab in the left nostril | Experimental | Not described Receives: Diagnostic Test: 2 cm nasal swab in the left nostril; Diagnostic Test: 4 cm nasal swab - right nostril |
What is being measured
The primary outcome is the main question the study is designed to answer.
Diagnostic accuracy (sensitivity and specificity) of SARS-CoV-2 antigen rapid diagnostic tests (Ag-RDTs) using nasal swabs collected at 2 cm versus 4 cm insertion depth, with RT-PCR as the reference standard
Measured: Baseline (during the study visit at the time of sample collection). Ag-RDT results were available immediately, whereas RT-PCR results were reported the following days (1-3 days).
Secondary outcomes (2)
Test discomfort on a 10-point VAS-scale
Test discomfort was evaluated using a 10-point visual analogue scale (VAS), ranging from 0 (no discomfort) to 10 (worst imaginable discomfort).
Measured: Baseline (during the study visit at the time of sample collection).
Self-reported symptoms of disease
Self-reported symptoms of SARS-CoV-2 infection collected via questionnaire at enrollment, including presence, type, and duration of symptoms (e.g., fever, cough, sore throat, nasal congestion, loss of taste or smell)
Measured: Baseline (during the study visit at the time of sample collection). Self-reported symptoms of disease were collected immediately prior to testing, during the study visit.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 May 2026
- Study start1 Feb 2023
- Primary completion26 Feb 2023
- Study completion26 Feb 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for COVID -19Studies of the same condition, open and under way.
- More trials run by Copenhagen University Hospital, RigshospitaletThe 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
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 317 participants (actual)
Sponsor and investigators
- Lead sponsor
- Copenhagen University Hospital, Rigshospitalet
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Tobias Todsen, Copenhagen University Hospital, Rigshospitalet
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07597889
- Sponsor's protocol ID
- Rigshospitalet
- Status last verified
- May 2026
- First submitted
- 29 Apr 2026
- Last updated
- 19 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Study Protocol
Study at a glance
From the registry record, last updated by the sponsor on 19 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Diagnostic Accuracy of 2 cm Versus 4 cm Insertion Depth for Nasal Swabs for SARS-CoV-2 Rapid Antigen Testing-A Randomized Controlled Trial
- ClinicalTrials.gov ID
- NCT07597889
- Acronym / sponsor ID
- Rigshospitalet
- Conditions
- COVID -19
- Keywords
- covid-19
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 317 participants (actual)
- Lead sponsor
- Copenhagen University Hospital, RigshospitaletUniversity, hospital or other
- Study start
- 1 Feb 2023 (actual)
- Primary completion
- 26 Feb 2023 (actual)
- Study completion
- 26 Feb 2023 (actual)
- First posted
- 19 May 2026 (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.
This study aims to compare the diagnostic accuracy of rapid antigen detection tests (RDTs) for SARS-CoV-2 using nasal swab insertion depths of 2 cm versus 4 cm.
The study is an investigator-initiated, randomized clinical trial conducted at a public COVID-19 test center in Copenhagen, Denmark.
Following enrollment, participants complete a questionnaire regarding symptoms and vaccination status.
Participants are randomized in a 1:1 ratio to one of two sampling sequences: either a 2 cm swab in the left nostril and a 4 cm swab in the right nostril, or vice versa. All participants undergo a healthcare worker-collected throat swab for RT-PCR analysis, which serves as the reference standard for SARS-CoV-2 infection.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| 2 cm nasal swab in the right nostril, and 4 cm nasal swab in the left nostril | Experimental | Diagnostic Test: 4 cm nasal swab - left nostril, Diagnostic Test: 2 cm nasal swab - right nostril |
| 4 cm nasal swab in the right nostril, and 2 cm nasal swab in the left nostril | Experimental | Diagnostic Test: 2 cm nasal swab in the left nostril, Diagnostic Test: 4 cm nasal swab - right nostril |
Who may qualify
- Ages
- 16 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult, Older adult
Key inclusion criteria (1 listed)
- Citizens, aged 16 years or older, showing up for a SARS-CoV-2 RT-PCR test at Testcenter Valby in Copenhagen, Denmark
Key exclusion criteria (2 listed)
- non-fluent in Danish
- citizens with nasopharyngeal or oropharyngeal anomalies (e.g. neck breathers with tracheostomy)
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 |
|---|---|---|
| 4 cm nasal swab - left nostrila 4 cm nasal swab insertion in the left nostril | Diagnostic test | 2 cm nasal swab in the right nostril, and 4 cm nasal swab in the left nostril |
| 2 cm nasal swab in the left nostrila 2 cm nasal swab insertion in the left nostril | Diagnostic test | 4 cm nasal swab in the right nostril, and 2 cm nasal swab in the left nostril |
| 4 cm nasal swab - right nostrila 4 cm nasal swab insertion in the right nostril | Diagnostic test | 4 cm nasal swab in the right nostril, and 2 cm nasal swab in the left nostril |
| 2 cm nasal swab - right nostrila 2 cm nasal swab insertion in the right nostril | Diagnostic test | 2 cm nasal swab in the right nostril, and 4 cm nasal swab in the left nostril |
Primary outcome
Diagnostic accuracy (sensitivity and specificity) of SARS-CoV-2 antigen rapid diagnostic tests (Ag-RDTs) using nasal swabs collected at 2 cm versus 4 cm insertion depth, with RT-PCR as the reference standard
Time frame: Baseline (during the study visit at the time of sample collection). Ag-RDT results were available immediately, whereas RT-PCR results were reported the following days (1-3 days).
2 secondary outcomes
Test discomfort on a 10-point VAS-scale
Time frame: Baseline (during the study visit at the time of sample collection).
Self-reported symptoms of disease
Time frame: Baseline (during the study visit at the time of sample collection). Self-reported symptoms of disease were collected immediately prior to testing, during the study visit.
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 May 2026.
- Individual participant dataSharing planned: Yes. Study Protocol
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing 4 cm nasal swab - left nostril, 2 cm nasal swab in the left nostril and 4 cm nasal swab - right nostril in people with COVID -19, run by Copenhagen University Hospital, Rigshospitalet at 1 site in Denmark.
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 1 inclusion and 2 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 May 2026. 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 Denmark. 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?
Diagnostic accuracy (sensitivity and specificity) of SARS-CoV-2 antigen rapid diagnostic tests (Ag-RDTs) using nasal swabs collected at 2 cm versus 4 cm insertion depth, with RT-PCR as the reference standard (time frame: Baseline (during the study visit at the time of sample collection). Ag-RDT results were available immediately, whereas RT-PCR results were reported the following days (1-3 days).). 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 May 2026; AzTrials last refreshed its copy on 31 Oct 2026.