April 27, 2022— Tony Keating hopes that millions of smartphone users will soon be coughing into their screens. His company, ResApp Health, in Brisbane, Australia, has developed a smartphone app to analyze the sound of coughs for what he says is a distinctive ''signature" that indicates COVID-19.

The app is one of several newly available or developing options to detect COVID-19. Testing is about to become easier, more accessible, and, in some cases, far less intrusive.

That's good news, say public health experts. Demand for testing has ebbed and flowed along with case counts and pandemic fatigue, but it remains a critical weapon against the spread of COVID-19.

Testing should be ongoing, says Jessica Malaty Rivera, an epidemiologist and senior advisor at the Pandemic Prevention Institute of the Rockefeller Foundation.

"From day one we have never tested enough," she says, adding that sufficient testing can help to get ahead of the virus instead of the reactive response that has marked the pandemic.

The new options include testing in the home as well as in doctor's offices, public health locations, and other sites.

Smartphone Testing

ResApp can use a smartphone to analyze a natural cough or a forced one, such as when someone deliberately coughs into the device, Keating says. COVID-19 changes the lungs in a very unique way, deep down in the lungs, he says, giving each cough a signature sound.

The ResApp's screening test uses machine learning to analyze that sound, and the results are transmitted to a healthcare provider who can then make a diagnosis.

The company already has received approval in Australia and Europe for the app to detect pneumonia and other respiratory conditions. Keating, its CEO, hopes to get approval for the COVID-19 application next.

In March, ResApp released results from a pilot clinical trial of 741 patients in the United States and India, in which 446 patients tested positive for COVID. In the trial, the app correctly identified positive patients 92% of the time (sensitivity) and correctly identified those without the disease 80% of the time (specificity).

According to Keating, in a population where 5% of people have COVID-19, the algorithm would produce a negative predictive value of 99.5%, meaning those who receive a negative result are likely truly negative and would not need a follow-up test.

If it's positive, he says, they recommend confirming the diagnosis with either a polymerase chain reaction (PCR) test, currently the gold standard in which a sample is sent to a lab, or a point-of-care rapid antigen test "to make sure."

Keating says his company is working with the FDA about "the right pathway to take" to get authorization.

If approved, he says the app it could be built into an Apple or Google device, or it could be built into an app you already use, such as for a flight check-in. The app could also be useful in other areas where frequent testing is needed, such as schools and healthcare settings.

Lab Quality, Less Delay

Scientists are also working on tests that would be as good as a molecular-based lab test without the delay in getting results.

Coming soon, developers hope, is a home-based test with PCR quality that will detect COVID-19 and the flu with a single test and will deliver results quickly. At least two companies are developing the tests.

Three PCR-quality COVID-19 tests for home use now have received emergency use authorization (EUA) from the FDA. The tests are pricier than antigen-based tests, but the promise of PCR accuracy without the need to rely on a lab attracts buyers, developers claim.

''We combine the accuracy of a PCR test with the convenience of antigen tests," says Owen Kaye-Kauderer, chief strategy officer and co-founder of Detect, which offers such a test.

The company's Detect COVID-19 Test requires a hub — which processes the test — and the test itself. The starter kit with hub and test is $85, while additional tests are $49. If the first test is negative for someone with no symptoms and no exposure, a second test must be done in 24 to 48 hours.

If there has been an exposure, whether the user has symptoms or not, one test is sufficient. The test requires 3 minutes of ''hands-on'' time and gives results in 1 hour at home. "Sensitivity round ups to 91%; specificity is 100%," Kaye-Kauderer says.

Cue Health, which charges $249 for its reader, a one-time purchase, and $195 for a three-pack of tests, has a sensitivity of 97% and a specificity of 99%, according to the company. For additional fees, it offers a monthly membership with discounts, 24/7 access to virtual care, and other features. Results are delivered to a mobile device in 20 minutes.

Lucira's Check-It COVID-19 test kit is 98% accurate compared to an FDA-authorized high-quality PCR test, the company claims. Results are available in 11 minutes (if positive) and within 30 minutes (if negative). The cost is $75 per test.

Saliva Test

A new saliva test, authorized by the FDA on April 14, is done in doctors' offices and eliminates the need for a nasal swab. It produces PCR-level results in 27 minutes, according to the company that makes it.

The FDA granted the EUA on the basis of an 87.2% sensitivity or positive percent agreement and a 97.2% specificity or negative percent agreement, says Jeff Chapman, president and CEO of Virginia-based MicroGEM US Inc.

During the research, which included children aged 5 years and older as well as adults, participants said they preferred the saliva sample over the nasal swab needed for other tests, Chapman says. When it came to contributing their saliva sample by spitting, kids "actually had fun," he says.

Someone spits less than a quarter teaspoon of saliva into a cup that is mixed, loaded into the instrumentation, and analyzed. But it comes at a cost. The MicroGEM Sal 6830 point-of-care system costs $9500. Leasing is also an option, Chapman says. A test costs $37.

"We expect to be shipping product, crossing our fingers, by the end of this month," Chapman says.

Breath Test

In mid-April, the FDA issued an EUA to Inspect IR Systems, of Frisco, Texas, for the first COVID-19 diagnostic test that detects chemical compounds called volatile organic compounds (VOCs) in breath samples associated with a SARS-CoV-2 infection.

The Inspect IR COVID-19 Breathalyzer can rapidly identify five VOCs linked with SARS-CoV-2 infection in exhaled breath. The instrument used for the test is about the size of carry-on luggage.

In a study of 2409 people, some of whom had symptoms and some who did not, the test had a 91.2% sensitivity and a 99.3% specificity.

But, it can only be used in licensed test settings, so it is not currently meant for home use.

Doggie Detectives

Dogs have an extraordinary sense of smell, which can be put to good use for COVID-19.

Researchers at the London School of Hygiene and Tropical Medicine, collaborating with Medical Detection Dogs, based in the U.K., as well as other researchers elsewhere, continue to study the ability of trained dogs and organic semiconducting sensors to distinguish between people who are infected with mild or no symptoms and people who are not infected.

In a recently published study, the London researchers report that people infected with SARS-CoV-2 who have no symptoms or mild ones have a distinct odor that can be identified by sensors and trained dogs with a high degree of accuracy.

The best-performing dogs had a sensitivity of up to 94.3% and a specificity of up to 92% in identifying COVID-19, the researchers said. The dogs can be put to work at airports and public events.

Importance of Continued Testing

Testing isn't important just to diagnose someone as being positive, Malaty Rivera says; it is also important for breaking the cycle of transmission.

With mandates loosening around the country, "we need to be placing a greater emphasis on testing," says Darshak Sanghavi, MD, chief medical officer of Babylon, a digital healthcare company.

A mix of home tests and other methods to provide accessible and affordable options for all is needed, he says.

The faster results provided by some of the newer methods, he says, will also permit more ''testing-to-treat," with medications that hopefully will be available immediately after a positive test, especially for high-risk people.

The range of options and price points now available, he says, will allow for continued testing and will help address health inequities.

Show Sources

Tony Keating, CEO, ResApp Health, Brisbane, Australia.

Jessica Malaty Rivera, epidemiologist, senior advisor, the Pandemic Prevention Institute of the Rockefeller Foundation.

Owen Kaye-Kauderer, chief strategy officer, co-founder, Detect, Guilford, CT.

Cue Health, San Diego, CA.

Lucira Health, Emeryville, CA.

Jeff Chapman, president, CEO, MicroGEM US Inc., Charlottesville, VA.

Inspect IR Systems, Frisco, TX.

Journal of Travel Medicine: “Using trained dogs and organic semi-conducting sensors to identify asymptomatic and mild SARS-CoV-2 infections: an observational study.”

Darshak Sanghavi, MD, chief medical officer, Babylon Health, Palo Alto, CA and London, UK.

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