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Review
. 2021 Jul 20;16(7):e0254559.
doi: 10.1371/journal.pone.0254559. eCollection 2021.

Relative sensitivity of anterior nares and nasopharyngeal swabs for initial detection of SARS-CoV-2 in ambulatory patients: Rapid review and meta-analysis

Yaolin Zhou  1 , Timothy J O'Leary  2   3
Affiliations
Free PMC article
Review

Relative sensitivity of anterior nares and nasopharyngeal swabs for initial detection of SARS-CoV-2 in ambulatory patients: Rapid review and meta-analysis

Yaolin Zhou et al. PLoS One. .
Free PMC article

Abstract

Nasopharyngeal (NP) swabs are considered "gold standard" for diagnosing SARS-CoV-2 infections, but anterior nares or mid-turbinate swabs (nasal swabs) are often used. We performed a meta-analysis comparing the sensitivity of nasal and nasopharyngeal swabs against a composite reference standard for the initial diagnosis of SARS-CoV-2 infection in ambulatory patients. The study is registered on PROSPERO (CRD42020221827). Data sources included studies appearing between January 1, 2020 and March 20, 2021, identified by searches of PubMed, medRxiv and bioRxiv. Studies included at least 20 subjects who simultaneously provided nasal and nasopharyngeal specimens for reverse transcription-polymerase chain reaction testing, and for which confusion matrices could be constructed. Authors individually assessed studies for inclusion and compared assessments. Each author independently extracted all data elements; differences were reconciled by review of initial data sources. Extracted data included specimen site, patient characteristics, collection site, and confusion matrices comparing results for nasal and nasopharyngeal swabs. Assessed against a composite reference standard, anterior nares swabs are less sensitive (82% - 88%) than nasopharyngeal swabs (98%). For populations with 10% specimen positivity, the negative predictive values of all swab types were greater than 98%. Mid-turbinate and anterior nares swabs seem to perform similarly. The lower sensitivity associated with nasal swab SARS-CoV-2 diagnosis is justified by the ability to screen more patients and reduced personal protective equipment requirements. Our conclusions are limited by the small number of studies and the significant heterogeneity of study designs and study outcomes.

Conflict of interest statement

I (TJO) have read the journal’s policy and the authors of this manuscript have the following competing interests: I have collaborated with Dr. Tu, who’s work is cited, and serve on a committee with Dr. St. George, whose work is cited. I serve as a member of the Scientific advisory Board of Integrated Nano-Technologies, and have consulted for MDisrupt. Dr. Zhou has no competing interests.

Figures

Fig 1
Fig 1. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.
*Some papers excluded for more than one reason †Meta-analysis performed with and without studies that had risk of selection bias.
Fig 2
Fig 2. Computer output showing sample sensitivity forest plots and meta-analysis results (studies with low risk of recruitment bias).
(A) Results for nasopharyngeal specimens. (B) Results for anterior nares specimens. (C) Exploratory analysis in which the Albany cohort from Griesemer [9] was excluded.
Fig 3
Fig 3. Computer results from unplanned exploratory analysis to include all anterior nasal swab and middle turbinate samples.
(A) Results for NPS from all cohorts included in this review. (B) ANS+MTS from all cohorts except the Griesemer [9] Albany cohort and the Callahan [3] cohort. Only ANS results are included from the Tu study [2].
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Grant support

The authors received no specific funding for this work.