One year ago, when the coronavirus pandemic was first tearing through the United States, experts bemoaned the lack of fast, accurate, and portable tests to diagnose COVID-19. Now, finally, rapid at-home tests have started appearing on drug store shelves—these are tests that are sold over the counter, without need for a prescription.
But the tests are rolling out just as vaccinations pick up steam in the United States and some other fortunate countries. Is this a case of innovation that’s too late to make a difference?
The first at-home test to get emergency-use approval by the U.S. Food and Drug Administration comes from Ellume, a company based in Australia. IEEE Spectrum spoke with Ellume CEO Sean Parsons about how he imagines his company’s test being used in the next phase of the pandemic.
Spectrum:Can you start by explaining how a customer uses your test?
Sean Parsons: Everything you need is in the box except the app, which you need to download onto your phone. The app has step-by-step instructions for how to use the test. All the brains are in the analyzer. The measurements are taken in the analyzer and a Bluetooth chip sends the results to your smartphone.
The test has this tube with a little bit of fluid, which is a buffer designed to capture the sample. You take a swab, which has to go a little bit further back than the nostril. It's much less unpleasant than typical nasopharyngeal swabs, and it provides just as good a sample. If you don’t get a reliable sample, you don’t get a reliable result. Then you mix it up, and you put the sample onto the test by squeezing the dropper.
The analyzer tests for COVID, and it also tests for a human protein to make sure you’ve collected a proper sample. We’re the only rapid antigen test that has an internal control, the others haven’t figured that out yet. The analyzer takes measurements every five seconds, so a bunch of data gets recorded. It gets run through an algorithm, which lives in the microprocessor. The result is compared to pre-set thresholds, and then the data gets transmitted to your phone. The whole thing takes 15 minutes.
How does it work?
If you open up the analyzer, you’ll see the electronics; underneath that is the assay strip, which is the medium that the sample travels in, and underneath that are the optics.
Immunochromatography is what happens on the strips. We use a sandwich immunoassay, which is a reasonably standard technique. The meat in the sandwich is the COVID protein, the bread in the sandwich is the antibodies. There are capture antibodies stuck on a membrane, so when a COVID protein floats by, it gets stuck to the antibodies. There are also fluorescent particles with antibodies on them, which bind to the COVID proteins. If you’ve got COVID present, you get an accumulation of these fluorescent quantum dot particles in the test zone.
When you excite it with a blue LED, that will lead to a higher amount of near infrared light emitted from that test zone. And we measure that light and compare it to preset threshold.
That optical piece focuses light from LEDs on the circuit board onto parts of the assay, and focuses light from the assay onto the photo transistor on the board. It’s a tiny little lens that’s relatively cheap to manufacture, relatively expensive to design. Underneath that is the single-sided circuit board with as few components as we can possibly manage. It has two LEDs in the blue UV range and a photo transistor. There are another two LEDs for the control system and a separate photo transistor. It has a few components to manage power, and our little microprocessor, which includes the Bluetooth. The challenge is making it all simple and scalable and robust.
Were you working on these technologies before the COVID-19 pandemic?
Yeah, we’ve been beavering away for the best part of a decade, trying to make a home flu test. These things take a long time to develop. When COVID arose, we quickly looked to modify the biology to be able to detect COVID.
How far along in your expansion plans is your North American manufacturing facility? And how soon before these kits are on drug store shelves?
The product is on shelves right now in some CVS stores, and it will be available nationwide within weeks. That product is coming from Australia at the present time, while we're ramping up our U.S. production. We’ll have product coming out of the U.S. facility and into stores in the third quarter.
How much will a kit sell for?
CVS is in charge of the final price. They’re putting it at $38.99 at the moment.
The big question right now is what role testing should play over the coming months or years in countries like the United States, where many people are already fully vaccinated. What role do you see testing playing?
Testing will be really important through the next 12 months as Americans get more comprehensively vaccinated. There’s a lot of concern about vaccine longevity, which is very important. America will be getting back to work, and people will be starting to go back to the office, but then the seasonal flu will come up next winter. … There will be a lot of people who will want to know that they don’t have COVID. And a lot of employers who will want to know that their employees don’t have COVID. For the next 12 months especially, there will be quite a strong need for frequent single-use testing.
And I guess the test could be used in school settings? It seems like it will still be a while before kids are vaccinated.
The test can be used with children older than two. The swab has this adapter which you can put on if you’re swabbing a child, so the tip doesn’t go in as far.
So that’s your plan for the United States, where vaccination rates are rising. What about the many countries in the world that haven't gotten very far with vaccinations yet?
Ellume is very focused on America at present time. Later this year and into next year, when we hope to have more manufacturing capacity, we’ll be able to expand internationally. We definitely want to leverage our manufacturing to the greatest extent possible. We want to help the world recover from COVID, and help people get back on planes and see their families.
This interview has been edited and condensed for clarity.
Eliza Strickland is a senior editor at IEEE Spectrum, where she covers AI, biomedical engineering, and other topics. She holds a master’s degree in journalism from Columbia University.