Saliva compares to nasal swabs for COVID-19 test

As a highly transmissible Delta variant of the virus that causes outbreaks of COVID-19 in the United States and around the world, rapid and accessible COVID-19 testing and increased vaccination are essential to manage the spread of the virus. Nasopharyngeal (NP) swabs – long, medical-grade probes used to collect samples from deep in the nose and throat of patients – are the gold standard for COVID-19 diagnostic testing. However, memory of shortages of both specialty NP swabs during the early days of the pandemic as well as the pressure on trained medical personnel needed to perform the tests point to the need for simpler COVID-19 testing.

In a real-world trial, a team of clinician scientists at Beth Israel Deaconess Medical Center (BIDMC) demonstrated that tests of self-collected saliva provided results comparable to tests performed by healthcare professionals trained in the field. using NP swabs. The researchers concluded that saliva tests detect 93% of outpatient COVID-19 infections. The results, published in the journal Microbiology spectrum, could help ease testing bottlenecks that have limited COVID-19 testing since the start of the pandemic.

“Self-collection of saliva is simply easier and more comfortable than the alternative of NP swabs, which, in addition to the discomfort, also require a trained healthcare professional,” said corresponding author Ramy. Arnaout, MD, DPhil, Associate Director of Clinical Microbiology Laboratories at BIDMC. “Besides being a more convenient method, our results show that saliva collection can also be just as effective, even in a real world scenario in which there is no restriction on eating or drinking before the saliva is collected. “

Arnaout and his colleagues obtained two samples – one via an NP swab, the other from saliva – from 385 patients presenting for a COVID-19 test at BIDMC. Patients queuing for the NP test were given a sterile specimen collection cup and were asked to provide a three milliliter saliva sample. The saliva samples were either treated untreated or treated with a preservative, and all samples were tested on two different COVID-19 testing platforms.

After finding that viral particles remained stable in both treated and untreated saliva samples for at least 24 hours, the researchers demonstrated a strong agreement, or agreement, between saliva tests and NP tests. In other words, the results came back the same 93 percent of the time. Of the 385 samples collected, only nine showed discordant results between PN and saliva test results. Most of the discrepancies were at very low viral loads, which made them clinically less worrying, and the saliva detected as many infections as NP missed, and vice versa.

Arnaout and his colleagues reported that the sensitivity of NP tests was still slightly higher than that of saliva tests, with NP tests being able to detect viral particles at lower concentrations. However, the researchers found that saliva tests are still likely to detect 90 percent of COVID-19 infections, and concluded that the minor loss of sensitivity is offset by the ease and safety of self-collection.

“We have shown that for practical purposes, saliva is comparable to NP swabs for outpatient COVID-19 testing,” said Arnaout, who is also an associate professor of pathology at Harvard Medical School.

Study results were announced in tandem with a first-person retrospective and analysis published in the Journal of Clinical Microbiology in which Arnaout details the collaborative and open source effort he coordinated to address the swab shortage that has hampered the country’s ability to test and track the spread of COVID-19 at the start of the pandemic, and details lessons learned. The team’s previous efforts to catalyze the development of new designs of NP swabs that can be manufactured quickly and in large numbers have resulted in four 3D printed prototypes that have been validated in clinical trials. The four swab prototypes were selected from more than 100 swab designs composed of 45 different materials submitted by 23 companies, laboratories and individuals across the country for BIDMC evaluation.

Reference: Callahan C, Ditelberg S, Dutta S, et al. Saliva is comparable to nasopharyngeal swabs for the molecular detection of sras-cov-2. Powell EA, ed. Microbiol spectrum. 2021. doi: 10.1128 / Spectrum.00162-21

This article has been republished from the following documents. Note: The material may have been modified for its length and content. For more information, please contact the cited source.