New COVID test will take your breath away

Sticking a swab up your nose might be a thing of the past shortly: American scientists have created a fast-working breath test that identifies traces of the virus that causes COVID-19.

The team from Washington University in St Louis, USA, made tiny green breathalysers for use in medical practices. They expanded on previous research that developed monitors to detect airborne molecules of SARS-CoV-2 indoors.

When a person breathes into the breathalyser, the virus’s spike proteins bind to a nanobody – in this case, a specialised llama antibody. Once attached, the biosensor oxidises tyrosine amino acids within the protein, and the device measures this electrochemical process to confirm a positive sample.

The research team estimates each test costs less than US$10 (about AU$15) and takes under 2 minutes to provide and analyse the sample in a specialised machine.

It’s also suggested the breathalyser could be adapted to test for other respiratory diseases, including influenza, rhinovirus and RSV.

“With this test, there are no nasal swabs and no waiting 15 minutes for results, as with home tests,” said co-senior author Associate Professor Rajan Chakrabarty from WashU’s McKelvey School of Engineering.

“A person simply blows into a tube in the device, and an electrochemical biosensor detects whether the virus is there. Results are available in about a minute.”

In lab testing, COVID-positive patients were asked to breathe 2, 4 or 8 times into the tube to return a result. It identified both the ancestral and circulating Omicron strains of the virus after 2 exhalations. Results from the testing were within 20% of those from standard methods (like RAT and PCR) and returned no false negatives.

The device is now being tested in a clinical trial.

Study co-author Professor John Cirrito from WashU’s School of Medicine suggests the real-world application for the device – which already has a medical technology company in line to licence the product – would be within settings that require fast and accurate results, such as public events and spaces.

“If people are in line to enter a hospital, a sports arena or the White House Situation Room, 15-minute nasal swab tests aren’t practical,” Cirrito says.

“And PCR tests take even longer. Plus, home tests are about 60% to 70% accurate, and they produce a lot of false negatives. This device will have diagnostic accuracy.”