The researchers evaluated SARS-CoV-2 detection in paired nasopharyngeal swabs and saliva samples collected from COVID-19 inpatients and asymptomatic healthcare workers at moderate-to-high risk of COVID-19 exposure. They collected clinical samples from 44 COVID-19 inpatient study participants—all of whom had serious illness—and 98 health care workers. After testing for the presence of the SARS-CoV-2 virus, the findings suggest that saliva samples provided greater detection, sensitivity, and consistency throughout the course of infection than the nasopharyngeal swabs.
This is a “super useful new study,” tweeted Akiko Iwasaki, PhD, professor at the Yale School of Medicine, showing that “saliva is a better diagnostic sample for COVID-19 testing than nasopharyngeal swabs.”
When the authors compared SARS-CoV-2 detection from patient-matched nasopharyngeal and saliva samples, they found that “saliva yielded greater detection sensitivity and consistency throughout the course of infection.” In addition, there was less variability in self-sample collection of saliva.
The experiment also detected SARS-CoV-2 from the saliva of two asymptomatic healthcare workers who tested negative from their nasopharyngeal swabs. This finding, tweeted Anne Wyllie, PhD, associate research scientist in epidemiology at Yale School of Medicine and lead author on the study, “suggests that saliva could be a viable alternative for identifying mild or subclinical infections.”
With further validation, Wyllie asserts, “widespread use of saliva sampling could be transformative for public health efforts.”
A group of researchers from Melbourne, Australia, published similar findings last week in a paper, “Saliva as a non-invasive specimen for detection of SARS-CoV-2,” published in the Journal of Clinical Microbiology as a Letter to the Editor.
This study used samples taken between March 25 and April 1. During that time, 622 patients were tested for COVID-19 at the Royal Melbourne Hospital through the screening clinic. All patients had nasopharyngeal swab samples, and 522/622 (83.9%) patients also provided saliva.
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