How a simple smell test could curb COVID-19 and help reopen the economy – featured on CU Boulder

A simple, scratch-and-sniff test could play a key role in curbing the spread of COVID-19, at a fraction of the cost of high-tech tests that are difficult to scale and take longer to return results, new CU Boulder research suggests.

“A lot of people have joked about this idea, but this is the first effort to ask in a rigorous, mathematical way: Could screening for loss of smell actually work?” said author Roy Parker, a professor of biochemistry and director of CU’s BioFrontiers Institute. “We were surprised by how good the results were.”

For the study, Parker and Dan Larremore, an assistant professor of computer science, teamed up with CU Boulder alumnus Derek Toomre, a professor at the Yale School of Medicine who has developed an index-card sized test that interacts with a smartphone app to assess sense of smell.

Studies show that, when simply asked about their symptoms, only about half of people with COVID-19 report loss of smell, or anosmia. But when given a standardized test, with no visual clues to alert them to what they’re smelling and a range of scents chosen to catch even faint loss of smell, that number rises to eight in 10, even among people with no other symptoms.

That’s far more prevalent than fever, which impacts fewer than one in four people with the virus. Anosmia also lasts longer, affecting patients for a week or more while fever may only last a day or two.

While fever is associated with many diseases, loss of smell without a stuffy nose is highly specific to COVID-19, possibly due to the fact the virus tends to enter the body and replicate via ACE2 receptors, which are extremely abundant in cells in nasal passages believed to influence sense of smell.

“Given that we are already broadly screening for temperature at places like hospitals and airports, we asked: ‘What would happen if we started screening for loss of smell instead?’” said Larremore.

One tool in the toolbox

Toomre, who graduated with a bachelor’s degree in biochemistry from CU Boulder in 1990, recently launched a company called usmellit to commercialize the test. It features five scratch-and-sniff squares and asks users to identify the five scents and enter the answer into their smartphone. It either tells them they passed or instructs them to get a COVID-19 test.

“We hope that it would allow for a fast and easy test that anyone can take anywhere and can be applied to anyplace that is using temperature screening as an inexpensive way to help avoid shutdowns, keep businesses open and decrease the terrible human toll,” he said.

The paper has not yet been published in a peer-reviewed journal, and the authors caution that more research, testing the idea in a broad community, is necessary before such tests could be broadly rolled out as a screening tool.

But they are optimistic.

“This is not a silver bullet,” said Larremore. “But it could be another useful tool in our repertoire of tools for getting a handle on this virus.”

Read the entire article from University of Colorado Boulder