Combined throat/nasal swab sampling for SARS-CoV-2 is equivalent to nasopharyngeal sampling

A L M Vlek*, T S Wesselius, R Achterberg, S F T Thijsen

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

39 Citations (Scopus)

Abstract

PURPOSE:

PCR on a nasopharyngeal sample is the reference method for the detection of SARS-nCoV-2. However, combined throat/nasal sampling as a testing method has several advantages. We compared the combined throat/nasal sampling with nasopharyngeal sampling for detection of SARS-CoV-2 in healthcare workers suspected of COVID-19.

METHODS: 

In 107 healthcare workers with symptoms of COVID-19, combined throat/nasal sampling and nasopharyngeal sampling was performed. Detection of SARS-CoV-2 was performed by RT-PCR targeting.

RESULTS:

 A total of 80 healthcare workers (74.8%) tested negative with both sampling methods, and 25 healthcare workers (23.4%) tested positive with both sampling methods. There were two discrepant results with positive PCR in combined throat/nasal swabs and negative PCR in nasopharyngeal swabs (1.9%). The κ index for concordance between the 2 sampling methods was high (0.95). The median cycle threshold (Ct) value of PCR on nasopharyngeal samples was significantly lower than the Ct value of PCR on combined throat/nasal samples (19 (IQR 17-20) versus 21 (IQR 18-29) cycles, p value 0.01).

CONCLUSION: 

Combined throat/nasal swabs yield a similar sensitivity to detect SARS-CoV-2 as nasopharyngeal swabs and are a good alternative sampling method, despite a lower Ct value for the nasopharyngeal samples.

Original languageEnglish
Pages (from-to)193-195
Number of pages3
JournalEuropean journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology
Volume40
Issue number1
DOIs
Publication statusPublished - Jan 2021
Externally publishedYes

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