Saliva, Nasopharyngeal Samples Equally Sensitive for SARS-CoV-2
Incremental cost of $8,093 per additional detection found with nasopharyngeal swab among individuals without previous SARS-CoV-2
TUESDAY, Jan. 12, 2021 (HealthDay News) -- There is no statistically significant difference in the sensitivity of saliva versus nasopharyngeal swabs for detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), according to a review published online Jan. 12 in the Annals of Internal Medicine.
Mayara Lisboa Bastos, M.D., from McGill University in Montreal, and colleagues examined the difference in sensitivity for SARS-CoV-2 detection between nasopharyngeal swabs and saliva. Data were included from 37 studies with 7,332 paired nasopharyngeal swab and saliva samples.
The researchers found that the sensitivity of saliva was 3.4 percentage points lower (95 percent confidence interval, −9.9 to 3.1 percent) than that of nasopharyngeal swabs against a reference standard of a positive result on either sample. The sensitivity of saliva was 1.5 percentage points higher (95 percent confidence interval, −7.3 to 10.3 percent) than that of nasopharyngeal swabs among patients with previously confirmed SARS-CoV-2 infection. Saliva was 7.9 percentage points less sensitive (95 percent confidence interval, −14.7 to 0.8 percent) among patients without a previous SARS-CoV-2 diagnosis. In this subgroup, nasopharyngeal swabs would detect 79 more persons (95 percent uncertainty interval, 5 fewer to 166 more) with SARS-CoV-2 than saliva if testing 100,000 persons with a SARS-CoV-2 prevalence of 1 percent, with an incremental cost of $8,093 per additional infection detected.
"Given these findings, plus the advantages of reduced invasiveness, reduced need for trained health care professionals, lower risk for occupational exposure, and reduced need for specialized supplies, we suggest that saliva sampling should replace nasopharyngeal swabs in most populations being tested for SARS-CoV-2," the authors write.