New Saliva-Based Antigen Rapid Testing Technology Developed by Singapore Scientists

By Cheryl Wong
Cheryl Wong
Cheryl Wong
December 16, 2021 Updated: December 16, 2021

A new type of saliva-based Antigen Rapid Testing (ART) technology to diagnose COVID-19 has been developed by scientists in Singapore, co-developed by the SingHealth Duke-NUS Academic Medical Centre and the National University of Singapore.

Called the Parallel Amplified Saliva rapid POint-of-caRe Test (PASPORT), it allows individuals to self-administer the test with a sensitivity higher than existing nasal swab ART tests and close to that of laboratory-based Polymerase Chain Reaction (PCR) tests.

Breakthrough COVID-19 Testing Technology

The new technology produces results within minutes, and can be done at home or at a point-of-care, for example, at airports. It is also done without the need for additional equipment or trained personnel. 

All individuals need to do is to spit in a plastic cup, use a provided dropper to insert the saliva into a well in the test kit, and wait for the completion of the test as indicated by a red dye in the window of the test kit.

According to a press release by Duke NUS, the invention was borne out of a research collaboration between Duke-NUS Medical School, Singapore General Hospital (SGH), and National Cancer Centre Singapore (NCCS).

Duke-NUS and SingHealth have also filed for intellectual property protection for the invention and entered into a license agreement with Singaporean company Digital Life Line Pte Ltd, hoping to put it out in the market as soon as possible to serve health care needs. 

In a clinical study involving over 100 participants at Singapore General Hospital, the test was found to have a sensitivity of 97 percent in detecting the virus, as compared to the PCR test’s sensitivity of 99.5 percent (pdf). The nasal swab-based ART has a variable sensitivity of around 80 percent. 

Professor Ooi Eng Eong, one of the senior co-inventors from the Duke-NUS Emerging Infectious Diseases Programme, said, “like COVID-19 vaccines, the availability of oral antiviral drugs will be another game changer in our fight against COVID-19.”

But these drugs will need to be given as early as possible after illness onset for maximal benefit. A test that can be self-administered or used on-site at the primary care setting may mitigate the need for cases to be managed at the hospitals,” he added.

Convenience of Saliva-Based Tests

Saliva-based tests are a lot more convenient than tests that use nasal or throat swabs. However, saliva tests have not been considered to be reliable enough to roll out on a mass scale, as the concentration of viral particles in saliva drops steeply after the individual eats or drinks. 

Hence, individuals could only administer saliva tests first thing in the morning before eating anything, and cannot do it any other time of the day, which makes it inconvenient for large-scale testing. 

The new PASPORT technology solves this issue using a two-stage process. PASPORT uses nanoparticles to bind to the virus like other ART tests, but it also adds a second type of nanoparticle that binds the first set of nanoparticles to amplify the signal.

This makes PASPORT more sensitive at detecting the virus and allows it to be used at any time of the day, and it can also achieve detection even at lower viral loads, unlike the current nasal swab ART test. 

Professor Soo Khee Chee, a Benjamin Sheares professor in Academic Medicine at the SingHealth Duke-NUS Oncology Academic Clinical Programme, a Senior Advisor to Duke-NUS, and a senior co-inventor, also said, “ Our invention ticks all the boxes for an ideal rapid test: ease of collection of saliva; highly accurate with very low false negative results, making it an invaluable screening tool; and can be done at any time of the day, making it possible to be used at point of care, with reliable authentication.”

He also added, “With this, we hope that more people will do the test as a personal act of social responsibility before engaging, especially in large-scale events or gatherings.”

Cheryl Wong