New, Fast, Portable Saliva Screening Test Uses Infrared Light Technology to Confirm SARS-CoV-2 Infection

International research has achieved a proof of concept for a new, fast, portable saliva screening test that uses an infrared light technology to confirm infection with SARS-CoV-2.

The new diagnostic approach involving the use of a portable infrared instrument to detect the SARS-CoV-2 virus in saliva, was led by scientists at Monash University (Melbourne, Australia) and the Peter Doherty Institute for Infection and Immunity (Melbourne, Australia) and could pave the way for safer and more efficient COVID-19 testing.


The team identified a signature of the infectious agent in the infrared spectra of saliva from 27 out of the 29 SARS-CoV-2-infected human subjects with COVID-19-like symptoms. The scientists say this is very encouraging preliminary research and are keen to see further testing with a larger patient cohort to better understand the specificity of this approach. A portable infrared spectrometer was modified to enable high throughput screening enabling the samples to be rapidly scanned in a contactless mode without having to clean the instrument between measurements.

The researchers estimate that this technique could be capable of screening 5000 samples per day per instrument, with results for each sample being ready in five minutes. Because the infrared light interacted with the vibrations of molecules, it could be used to generate a spectrum that represented a unique chemical fingerprint of the sample that was then processed using machine learning algorithms. The proposed new test also avoids the discomfort associated with nasopharyngeal swabs, an advantage that could improve community participation in testing.

A similar infrared technique known as Attenuated Total Reflectance (ATR) spectroscopy has previously been used by the Monash researchers to detect malaria and hepatitis. The new transflection infrared based approach offers triple the absorbance and hence interrogates more saliva to detect pathogens compared to the traditional ATR technology. The speed and versatility of the technique potentiates its use for point-of-care screening at airports, sporting venues, universities or schools, to triage patients for RT-PCR testing.

“The most significant advantages of using this infrared-based technology on saliva samples, include the speed and ease with which the test can be performed, its affordability and the reduced risk to both patients and healthcare workers,” said Professor Bayden Wood from the Monash University School of Chemistry.

“The approach has significant advantages over the standard Real Time Reverse Transcription Polymerase Chain Reaction (RT-PCR) that is the current gold standard for detection,” said Professor Dale Godfrey from the Doherty Institute. “As we know, this requires that samples are sent to a dedicated laboratory and results take a day or more”.

“A person can contribute the sample by simply dribbling into a sterile container,” said Professor Damian Purcell from the Doherty Institute. “The result can be derived in less than five minutes and a rapid result minimizes the delay in determining if quarantine is required, therefore minimizing the risk of further spread of infection.”

Related Links:
Monash University
Peter Doherty Institute for Infection and Immunity