We use cookies to understand how you use our site and to improve your experience. This includes personalizing content and advertising. To learn more, click here. By continuing to use our site, you accept our use of cookies. Cookie Policy.

Features Partner Sites Information LinkXpress
Sign In
Advertise with Us
BIO-RAD LABORATORIES

Download Mobile App





Nasopharyngeal Swabs More Effective Than Saliva Tests at Detecting COVID-19

By LabMedica International staff writers
Posted on 06 Jun 2022
Print article
Image: Nostril swab may be the best way to test for COVID-19 (Photo courtesy of Unsplash)
Image: Nostril swab may be the best way to test for COVID-19 (Photo courtesy of Unsplash)

A new study has found that nasopharyngeal swabs – taken from far back inside the nostril – were more effective at detecting COVID-19 than saliva tests or swabs just inside the nostril or under the tongue. The study also found that detection rates were lower in asymptomatic patients, confirming the rationale for shortened isolation guidelines.

For the study, researchers at Cornell University (Ithaca, NY, USA) used different samples from patients: nasopharyngeal swabs, anterior nares swabs (front of the nostril), saliva and sublingual swabs (under the tongue). The researchers also collected samples from symptomatic, asymptomatic and post-symptomatic individuals – those who had recovered from illness – to better understand testing efficiency in these populations. When they compared the different sample types, the researchers found that nasopharyngeal samples provided the best rate of detection, from 92 to 100%. This is likely because the virus replicates in the nasal turbinate, the tissue structures in the uppermost portion of the nose.

Detection rates from anterior nares and saliva specimens were slightly lower, at 92 to 96% for symptomatic patients. This detection rate was lower when the samples that came from asymptomatic patients (75% to 92%). SARS-CoV-2 detection of sublingual specimens was much poorer, with detection rates of only 40 to 60% from symptomatic patient specimens and 25% to 42% from asymptomatic patient specimens. Detection rates in symptomatic, asymptomatic and post-symptomatic patients was fairly intuitive, with detection being most robust in symptomatic patients, ranging from 92 to 100%, depending on the test used. For all tests, the virus was slightly harder to detect in asymptomatic patients, at a rate of 75 to 96%. Once symptoms were resolved in post-symptomatic patients, detection was much more difficult.

The team also investigated infectivity – the level of infectious viral particles excreted in each of the sample types and from the different patient categories. As predicted, the most infectious samples came from symptomatic patients, while fewer than one-third of specimens collected from asymptomatic patients were infectious. The researchers were unable to isolate any infectious virus from post-symptomatic patient samples. This new data gives health practitioners some practical guidance.

“The study addressed the very important issue of identifying a sample type that would allow reliable detection of the virus, without significantly compromising the sensitivity of detection,” said Dr. Diego Diel, associate professor in the Department of Population Medicine and Diagnostic Sciences and director of the virology laboratory at the Animal Health Diagnostic Center, who was lead author of the study. “We were surprised at the relatively short period in which infectious virus was detected.”

Related Links:
Cornell University 

Platinum Member
COVID-19 Rapid Test
OSOM COVID-19 Antigen Rapid Test
Magnetic Bead Separation Modules
MAG and HEATMAG
Complement 3 (C3) Test
GPP-100 C3 Kit
New
Gold Member
COVID-19 Rapid Test
AQ+ COVID-19 Ag Rapid Test

Print article

Channels

Clinical Chemistry

view channel
Image: The 3D printed miniature ionizer is a key component of a mass spectrometer (Photo courtesy of MIT)

3D Printed Point-Of-Care Mass Spectrometer Outperforms State-Of-The-Art Models

Mass spectrometry is a precise technique for identifying the chemical components of a sample and has significant potential for monitoring chronic illness health states, such as measuring hormone levels... Read more

Molecular Diagnostics

view channel
Image: A blood test could predict lung cancer risk more accurately and reduce the number of required scans (Photo courtesy of 123RF)

Blood Test Accurately Predicts Lung Cancer Risk and Reduces Need for Scans

Lung cancer is extremely hard to detect early due to the limitations of current screening technologies, which are costly, sometimes inaccurate, and less commonly endorsed by healthcare professionals compared... Read more

Hematology

view channel
Image: The CAPILLARYS 3 DBS devices have received U.S. FDA 510(k) clearance (Photo courtesy of Sebia)

Next Generation Instrument Screens for Hemoglobin Disorders in Newborns

Hemoglobinopathies, the most widespread inherited conditions globally, affect about 7% of the population as carriers, with 2.7% of newborns being born with these conditions. The spectrum of clinical manifestations... Read more

Immunology

view channel
Image: Exosomes can be a promising biomarker for cellular rejection after organ transplant (Photo courtesy of Nicolas Primola/Shutterstock)

Diagnostic Blood Test for Cellular Rejection after Organ Transplant Could Replace Surgical Biopsies

Transplanted organs constantly face the risk of being rejected by the recipient's immune system which differentiates self from non-self using T cells and B cells. T cells are commonly associated with acute... Read more

Pathology

view channel
Image: Comparison of traditional histopathology imaging vs. PARS raw data (Photo courtesy of University of Waterloo)

AI-Powered Digital Imaging System to Revolutionize Cancer Diagnosis

The process of biopsy is important for confirming the presence of cancer. In the conventional histopathology technique, tissue is excised, sliced, stained, mounted on slides, and examined under a microscope... Read more
Copyright © 2000-2024 Globetech Media. All rights reserved.