JUL 07, 2020 6:23 AM PDT

Throat Swabs Prevent COVID False Negatives

WRITTEN BY: Tara Fernandez

False-negative results are particularly problematic in containing the spread of COVID-19 — infected individuals can unwittingly transmit the virus while being completely asymptomatic. Why do false negatives happen? A recent study by Johns Hopkins researchers reported that timing may be an important factor; testing too early increased the chances of a false negative test. Here, the authors estimated that those tested for SARS-CoV-2 four days after infection were 67 percent more likely to test negative, even if they had the virus.

A study published in the Journal of Dental Research proposes a new method for reducing the occurrences of false negatives, simply by changing the sample source.

There are two main COVID-19 diagnostic tests, one that detects the presence of the SARS-CoV-2 virus, and the other that picks up antibodies, the body’s immune response to infection. The viral tests involve swabbing the inside of the nose and analyzing the sample for trace amounts of viral genetic material.

A study led by Jingzhi Ma at Wuhan’s Huazhong University of Science and Technology discovered that some patients who had negative results from their nasal swabs did in fact test positive from swabs of their oropharyngeal secretions (OS). Sampling the oropharynx, an anatomical region that includes the soft palate, throat, tonsils, and back of the tongue may be a more effective approach for catching COVID-19 positive cases sooner.

The authors found that oropharyngeal swabs significantly outperformed nasal swabs in terms of both sensitivity and accuracy: throat swabs missed only 14 percent of positive cases, as opposed to almost 60 percent that were missed by the nasal swabs.

With over 11 million confirmed cases of COVID-19 worldwide, the race to find point-of-care diagnostics, effective therapeutics, and long-term protection through vaccines continue. In the lead up to these becoming widely available, early detection of cases coupled with physical distancing provide the best chances of coronavirus transmission among the community.

Ma and colleagues support making OS sampling the new gold standard for COVID-19 diagnostics. "The NPS test has a risk of sending home more patients who still have the infection while the OS test will make such errors in fewer patients. Although OS sampling improves the accuracy of SARS-CoV-2 nucleic acid testing, it must be emphasized that this conclusion is based on a very small sample size," said Ma.

 

 

Sources: Science Daily, Technology Networks, Journal of Dental Research.


 

About the Author
  • Tara Fernandez has a PhD in Cell Biology and has spent over a decade uncovering the molecular basis of diseases ranging from skin cancer to obesity and diabetes. She currently works on developing and marketing disruptive new technologies in the biotechnology industry. Her areas of interest include innovation in molecular diagnostics, cell therapies, and immunology. She actively participates in various science communication and public engagement initiatives to promote STEM in the community.
You May Also Like
SEP 05, 2021
Microbiology
Gut Bacteria May Influence Infant Brain Development
SEP 05, 2021
Gut Bacteria May Influence Infant Brain Development
Our health is closely connected to the community of microbes we carry in our gut. For example, these microbes have a pow ...
SEP 09, 2021
Clinical & Molecular DX
A Drug Test for Synthetic Cannabis Use
SEP 09, 2021
A Drug Test for Synthetic Cannabis Use
Designer drugs are synthetic analogs of prohibited substances such as cocaine and LSD made in clandestine laboratories a ...
OCT 04, 2021
Genetics & Genomics
Zaki syndrome - Pediatric Disorder & Potential Treatment ID'ed
OCT 04, 2021
Zaki syndrome - Pediatric Disorder & Potential Treatment ID'ed
Since it's become quick and relatively inexpensive to sequence a human genome, researchers have gained unprecedented and ...
OCT 25, 2021
Clinical & Molecular DX
Illuminating Blips in Blood Flow to the Brain
OCT 25, 2021
Illuminating Blips in Blood Flow to the Brain
  Just like an athlete needs to consume a huge number of calories to support their rigorous training regimes, neuro ...
NOV 02, 2021
Technology
Mini Sensors Help Detect Neuromotor Abnormalities in Infants
NOV 02, 2021
Mini Sensors Help Detect Neuromotor Abnormalities in Infants
Neuromotor abnormalities (such as abnormal movement and gross motor abilities) are often caused by often unseen damage t ...
NOV 16, 2021
Clinical & Molecular DX
Algorithm Mines Big Data, Finds Gene Linked to Psychiatric Disease
NOV 16, 2021
Algorithm Mines Big Data, Finds Gene Linked to Psychiatric Disease
We have a wealth of human genome data overlaid with gene ‘hotspots’ linked to the development of particular ...
Loading Comments...