An interventional study of 4 cm nasal swab - left nostril and 2 cm nasal swab in the left nostril in COVID -19, sponsored by Rigshospitalet, Denmark. Completed at 1 site in Denmark. Open to participants aged 16 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-19.
Sponsored by Rigshospitalet, Denmark · Not applicable, Interventional, and Diagnostic
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.
7,640 studies on the registry are indexed under COVID-19; 488 are open to participants now.
This study's enrollment of 317 is above the median of 100 across 4,099 interventional studies indexed under COVID-19.
Browse COVID-19 studies →Rigshospitalet, Denmark is the lead sponsor of 1,017 studies on the registry; 183 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Exclusion Criteria:
Diagnostic Test: 4 cm nasal swab - left nostril · Diagnostic Test: 2 cm nasal swab - right nostril
Diagnostic Test: 2 cm nasal swab in the left nostril · Diagnostic Test: 4 cm nasal swab - right nostril
a 4 cm nasal swab insertion in the left nostril
a 2 cm nasal swab insertion in the left nostril
a 4 cm nasal swab insertion in the right nostril
a 2 cm nasal swab insertion in the right nostril
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).
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).
Time frame: 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)
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.
Plan to share: Yes — Study Protocol
Supporting information: Study protocol
No publications or documents are linked to this record.
This study is completed, as verified in May 2026. You cannot join it, but the record below documents what was studied.
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Rigshospitalet, Denmark