New COVID-19 saliva test a possible game changer for rapid screening

 By Federico Graciano, Senior media and content specialist

Dr Danny Tng
Co-inventor and Duke-NUS alumnus Dr Danny Tng demonstrates how this novel saliva-based Antigen Rapid Test (ART) works 

As countries move to living with endemic COVID-19 and anti-COVID pills become available in primary-care settings, such as GP clinics, the eye-watering, sinus-stinging experience of an Antigen Rapid Test (ART) swab may become an integral part of the new normal.

To spare everyone’s sniffers, a team of scientists from Duke-NUS Medical School, Singapore General Hospital (SGH) and National Cancer Centre Singapore—collectively, members of the SingHealth Duke-NUS Academic Medical Centre—and the National University of Singapore has developed a saliva-based COVID-19 ART that has shown promise in early clinical testing, outperforming existing ARTs, with nearly comparable sensitivity to the gold standard Polymerase Chain Reaction (PCR) test.

Dubbed the Parallel Amplified Saliva Rapid Point-of-Care Test, or PASPORT, the technology leverages a proprietary on-kit amplification technique to produce results from a saliva sample in minutes.


Like other ARTs, PASPORT uses nanoparticles to bind the virus. But it is also coated with a second type of nanoparticles that binds to the first set in order to amplify the signal. Because of its two-stage amplification, PASPORT can detect viruses at much lower viral loads, making it more sensitive at flagging SARS-CoV-2, and allows it to be used any time of the day, even after eating or drinking. In a clinical study involving more than 100 participants, PASPORT’s sensitivity in detecting the virus was 97 per cent and its specificity, 90.6 per cent, comparable to the gold standard PCR test.

“A reliable and painless saliva antigen test that is affordable and convenient to perform would encourage more [people] to be tested, and more frequent testing,” said lead inventor Dr Danny Tng, Medical Officer with the Department of Infectious Diseases, SGH, and an adjunct Research Fellow with Duke-NUS’ Emerging Infectious Diseases (EID) Programme. Tng, who graduated from Duke-NUS in 2019, added, “This may enable us to manage COVID-19 more effectively not only at the point of care, but also in settings such as airports, conventions and even at home.”

Requiring only saliva pooled in the mouth, the test is simple and easy to use.

Comparison between how PASPORT and a conventional saliva-based ART processes samples
Unlike conventional ARTs, PASPORT uses a dual amplification technique to deliver accurate results even after eating or drinking

“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,” said Professor Soo Khee Chee, a senior co-inventor of the test, who is Benjamin Sheares Professor in Academic Medicine at the SingHealth Duke-NUS Oncology Academic Clinical Programme.

Duke-NUS and SingHealth have filed intellectual property protection for the invention, and have entered into a license agreement with Digital Life Line, a Singapore-based company. The inventors hope that through close collaboration with commercial partners, the product can be out in the market as soon as possible as countries around the world move to making treatments available faster and in primary healthcare settings.

“[Oral antiviral drugs] will need to be given as early as possible after illness onset for maximal benefit,” said Professor Ooi Eng Eong from Duke-NUS Medical School’s EID Programme. “A test that can be self-administered or used on-site in the primary care setting may mitigate the need for cases to be managed at the hospitals.”

Get the latest news and features delivered to your inbox.