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Patient-Collected Lower Nasal Specimens for SARS-CoV-2 Testing
Quick Takes
- Patient-collected lower nasal swab samples appear to be acceptable for SARS-CoV-2 PCR testing.
- Findings are promising and have important practical implications, but require validation in a different patient population and larger sample size.
Study Questions:
What are the sensitivity and specificity of patient-collected lower nasal specimens for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) testing?
Methods:
Stanford Health Care outpatients (n = 30) with a reverse transcriptase–polymerase chain reaction (PCR) test that was positive for SARS-CoV-2 in March 2020 agreed to return for a drive-through collection of three specimens: a patient-collected lower nasal swab (Puritan Sterile Foam Tipped Applicator; Puritan Medical Products), a physician-collected lower nasal swab (Puritan Sterile Foam Tipped Applicator; Puritan Medical Products), and a physician-collected oropharyngeal swab (FLOQ Swabs; Copan Diagnostics). Results of the three specimen types were compared.
Results:
Participants were predominantly white (20 participants [66%]), with no sex or age group predominance. Eleven participants (37%) had test results that were positive for SARS-CoV-2 across patient- and physician-collected specimens, and 18 participants (60%) had results that were negative for SARS-CoV-2 across patient- and physician-collected specimens. All except one patient had concordant testing results. The only discordant result was a participant whose self-collected nasal specimen tested positive, whereas both of their physician-collected specimens tested negative (3.30%; 95% confidence interval [CI], 0.08%-17.00%). The sensitivity of the patient collected specimens was 100% (95% CI, 72%-100%), and the specificity was 95% (95% CI, 74%-100%).
Conclusions:
Patient-collected lower nasal swabs appear to have acceptable sensitivity and specificity compared to physician-collected nasal or oropharyngeal swab.
Perspective:
Nasopharyngeal swabs for SARS-CoV-2 testing have been described as an uncomfortable experience at the least. Reliable, self-collected lower nasal samples would be less traumatic, facilitate in-home or office-based testing, and allow for dramatic expansion of testing. The findings from this small report are promising. However, the sample size was small, and given the variability of the false-negative rate reported for SARS-CoV-2 PCR testing, the findings need to be validated in a different clinical population, larger sample size, and different assays to assess the reliability of self-collected nasal specimens.
Clinical Topics: COVID-19 Hub, Prevention
Keywords: Clinical Laboratory Techniques, Coronavirus, COVID-19, Diagnostic Tests, Routine, Outpatients, Primary Prevention, Reverse Transcriptase Polymerase Chain Reaction, SARS Virus, Sensitivity and Specificity, severe acute respiratory syndrome coronavirus 2
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