COVID-19 Testing: Saliva NAAT Comparable to Nasopharyngeal Swabs

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Study authors assessed the diagnostic accuracy of saliva NAAT for COVID-19 due to the increased resources, such as trained personnel, required for nasopharyngeal swab NAAT.

Saliva nucleic acid amplification testing (NAAT) for the diagnosis of COVID-19 was found to be comparable to nasopharyngeal swab NAAT during a systematic review and meta-analysis. These results were published in JAMA Internal Medicine.

Researchers searched publication databases through August 2020 for articles on methods for detecting COVID-19 infections. This meta-analysis included 16 studies conducted throughout the United States, Asia, Europe, and Australia.

All studies tested for COVID-19 in pairs of samples to maintain diagnostic accuracy. The average number of sample pairs among the studies was 370 (standard deviation [SD], 616). Patients were tested in a variety of situations, including at hospital admission, when returning from traveling, and at drive-through testing sites. A minority of studies (n=5) tested only individuals who presented with COVID-19 symptoms.

Of the 5922 samples included in this meta-analysis, 941 were positive for COVID-19.

The pooled sensitivity for saliva NAAT was 83.2% (95% credible interval [CrI], 77.4-91.4) and specificity was 99.2% (95% CrI, 98.2-99.8). The sensitivities of each individual study ranged from 60.6% to 89.4% and the specificities from 98.8% to 99.3%.

Among only those studies that underwent peer review, the pooled saliva NAAT sensitivity was 85.6% (95% CrI, 77.0-92.7) and specificity was 99.1% (95% CrI, 98.0-99.8).

The pooled nasopharyngeal swab NAAT sensitivity was 85.7% (95% CrI, 76.5-93.4) and specificity was 98.9% (95% CrI, 97.4-99.7).

In studies that were conducted in ambulatory settings (n=9), the pooled saliva NAAT performance (sensitivity, 84.5%; specificity, 99.0%) remained comparable to that of the pooled nasopharyngeal swab NAAT performance (sensitivity, 88.0%; specificity, 98.7%).

This analysis was limited by the underlying studies, which were dominated by those which recruited patients without COVID-19 symptoms, indicating that sicker patients were underrepresented.

These data suggested that saliva NAAT may be as effective as nasopharyngeal swab NAAT for detecting COVID-19 infections, especially in the context of large, community-based testing programs.

Reference

Butler-Laporte G, Lawandi A, Schiller I et al. Comparison of saliva and nasopharyngeal swab nucleic acid amplification testing for detection of SARS-CoV-2: a systematic review and meta-analysis. JAMA Intern Med. 2021;181(3):353-360. doi:10.1001/jamainternmed.2020.8876