Throughout the pandemic, rapid antigen tests have served as essential tools for measuring and preventing the spread of COVID-19. Rapid tests — which are available at drug stores, online retailers and even for free from the United States Postal Service — can be conducted at home and produce results within 30 minutes.
Before these tests hit the shelves, they must be validated and authorized for use by the U.S. Food and Drug Administration (FDA). Through the Rapid Acceleration of Diagnostics (RADx) initiative launched by the National Institutes of Health (NIH), Emory researchers and members of the Atlanta community have played a significant role in the process of validating at-home tests.
Jodie Guest, PhD, professor and vice chair of the department of epidemiology at Emory’s Rollins School of Public Health, spoke to Wilbur Lam, MD, PhD, about his team’s work to bring new COVID-19 diagnostic tools to market and provide free testing to the Atlanta community. Lam is a principal investigator of the NIH-funded Atlanta Center for Microsystems Engineered Point-of-Care Technologies (ACME POCT), which serves as the national test verification center for the NIH’s RADx initiative.
Lam is also professor and W. Paul Bowers Research Chair in the department of pediatrics at Emory University School of Medicine and professor of the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. He is a pediatric hematologist/oncologist at Children’s Healthcare of Atlanta and serves as chief innovation officer for Children's Healthcare of Atlanta’s and Georgia Tech’s Pediatric Technology Center.
Their conversation is part of an online video series hosted by Guest, who also leads the Emory COVID-19 Outbreak Response Team, answering questions related to the COVID-19 pandemic.
Q: How did Emory researchers become involved in the development of COVID-19 tests?
A: In response to the pandemic, the NIH formed the RADx initiative to accelerate the development, validation and commercialization of point-of-care and home-based tests that can detect the virus that causes COVID-19.
The Atlanta Center for Microsystems Engineered Point-of-Care Technologies (ACME POCT) leads the test validation efforts for RADx. A joint effort by Emory University, Georgia Tech and Children’s Healthcare of Atlanta, ACME POCT fosters collaboration among clinicians, technologists and entrepreneurs to accelerate the innovation and translation of microsystems-engineered technologies — including microchip-enabled devices, microfluidics and smartphone-based systems.
“Because of our technology bent, and because we have big patient populations — the adult side at Emory and a very large pediatric population at Children's — when the pandemic started, the leadership of the NIH realized that we here in Atlanta were the perfect and ideal center to be the national test verification center for RADx,” says Lam. “What we've been doing since the pandemic is really serving as the eyes and hands, so to speak, for the NIH — but also more recently for the FDA, as well.”
“So much of this is a true team effort that I think really attests to what we here at Emory are really good at,” he adds. “We've been able to really put together some amazing teams who are able to focus on a singular mission, and I think that's something that many other institutions couldn't really do. We often get remarks on that, in a very positive way; you know, ‘How did you all at Emory do that?’ And I think it's because we do have this culture that allows us to all collaborate and work together under a single task and mission.”
Q: How does the ACME POCT team assess new COVID-19 tests?
A: With more than 150 collaborators spanning multiple institutions and disciplines, the ACME POCT team assesses new rapid tests using a large supply of patient samples.
“When a test comes to us for testing, we collect patient samples,” Lam explains. “Even when standard testing wasn't available yet, we had a community outpost where we were constantly collecting samples for standard PCR testing, and we would get another sample to ‘test the test’ at hand.”
At community sites, the team collects samples from patients with a range of COVID-19 symptoms, from asymptomatic to severely ill. With duplicate samples from each patient, RADx investigators validate new tests by comparing the rapid test results to the PCR results.
The team also draws upon a centralized biobank, which includes locally collected samples and samples sent to the center from around the world.
“Our pathology groups are constantly collecting samples, amassing a very large biobank,” Lam says. “In fact, we have the largest COVID-19 biobank in the country. We have every variant, we have every subvariant and we also leverage our DNA sequencing capabilities by multiple scientists here at Emory who can then characterize those samples when they come in.”
Additionally, the group’s Biosafety Level 3 (BSL3) laboratory utilizes live virus.
“We grow up all the variants of concern and we have the capability to culture these viruses, to therefore have different controlled concentrations of virus,” Lam says. “We find that to be a very nice resource, so that we can really determine what's called the ‘limit of detection’ of each test.”
“And then, in collaboration with our folks at Georgia Tech, we can do technology readiness level assessment,” he adds. Collaborators at Georgia Tech conduct a usability analysis to help determine whether the test is too complex for at-home use.
“Just because something works, may or may not mean that it's actually ready to hit the shelves,” Lam explains. “Could my mother use it, could my elderly aunt use it, could someone who has disabilities use it? That's another major component of assessment.”
Q: How many COVID-19 testing technologies has ACME POCT assessed?
A: “RADx knew that most of the tests wouldn't make it all the way past the finish line,” Lam says. “We were thinking almost like a venture capitalist, where we know that there's many, many projects and only a few will make it all the way — and that's pretty much what happened.”
“Our goal in the beginning of the pandemic was really to have two or three tests, especially home tests, make it past FDA Emergency Use Authorization, and that really panned out,” Lam says. “We've seen over 100 technologies now, but we've also helped about 15 technologies get their EUA — and we work in conjunction with the FDA on this. That's not a bad ratio, but certainly the majority were not ready.”
“Many of them are still being worked out by the technology developer,” he adds. “Just because those technologies didn't make it, doesn't mean that we won't see them in the near future.”
Q: How does the RADx team influence the development of the tests?
A: “My Outbreak Response Team and I were lucky enough to work with RADx and take a bunch of the tests that [RADx] had found could find the virus out into the field,” says Guest. “We would do regular, routine testing, that we know works, with people who came and needed to be tested, but we would also offer the opportunity for them to try out additional tests and then [RADx] would pair them together.”
“It was really interesting watching some of the different types of tests we did,” she continues. “We determined a couple saliva tests didn't sit well and you couldn't put them back on the table, so then there were some crafted little test-tube holders that we had. Watching people put those things together was a bit of a science experiment.”
Lam’s team sends feedback from groups like Guest’s Outbreak Response Team to the technology developers so that the tests can be improved for at-home use.
“Our feedback is always taken seriously,” he says. “When we report back our data and our observations, we've had many technology developers turn around and give us a new version within as short as several weeks. For example, if it's as easy as changing the instructions for use, which is pretty important, they can easily do that, and they have done that.”
Q: How do new variants of COVID-19 affect the assessment of the tests?
A: “To some extent, once we got the first authorizations for these rapid tests, we thought we were done,” Lam says. “And then these variants popped up, so what that meant was we had to actually repeat.”
“What RADx did was form something called the Variant Task Force, which our center is intimately a part of,” he continues. “That is a joint effort between the NIH, our center, the FDA, and CDC to some extent as well, where we're constantly watching which variants are popping up and then we get samples. We bring them into our biorepository, we grow them up in our BSL3 laboratory, we retest — and that's what we've been doing with every variant of concern that's been popping up.”
The center also works proactively to anticipate new variants.
“Dr. Eric Ortlund in biochemistry here in our School of Medicine is developing a novel assay in which, if we know the sequence of the variant — it could even be a hypothetical variant — and we know which antibodies the rapid tests use, we could then predict whether there might be a mismatch,” Lam says. “We could predict whether or not that specific test could miss that variant.”
Q: Are PCR tests better at detecting COVID-19 infection than rapid tests?
A: “Typically, a PCR test is probably able to detect the virus at a lower viral load than an antigen test,” Lam says. “That said, it really depends on what the context is and how you use it.
“Rapid tests are so much more readily available,” he continues. “You can do serial testing, and if you do serial testing where you test yourself on your first day of symptoms, second day, third day, fourth day, that does tend to mitigate the aspects of decreased sensitivity compared to PCR.” Many rapid antigen tests are sold in packages of two to encourage repeat testing, Guest notes.
“While there might be slightly decreased sensitivity compared to PCR tests, in general all the rapid tests have a very good specificity,” Lam adds. “What I often tell my patients is: if you're positive on a rapid test, you’re positive. So, really that's a good take-home message.”
Q: Is it better to use a nasal swab or a throat swab for a rapid test?
A: “One question that has popped up during Omicron, especially on social media just a few months ago, was people started testing different parts of their body; they started swabbing their throat,” Lam says. “And what the FDA and NIH asked us to do is, as we enroll our test subjects, could we swab them in different places and really answer the question: where is Omicron? Is it in the throat, is it in the nose, is it in saliva? And that's what we did for about 60 to 80 test subjects, and then tested some of these subjects over time, as well.”
“At least with that small cohort, what we found was that Omicron is kind of everywhere, and there's no real pattern,” he continues. “It goes from one place to another and in general it doesn't seem like the throat was any better of a place to swab than the nose. Therefore, our advice would be really to follow the instructions for use. So, if it's authorized for a nasal swab, that's what you should be using, and not a throat swab, because there hasn't been any established data for those different anatomic sites.”
Q: Does vaccination status affect the results of a rapid test?
A: “That's another experiment that we're currently conducting right now,” Lam says. “In theory, it might. One could envision how someone who's vaccinated has a pretty robust immune response and is getting rid of that virus, so that you can't even really swab enough to yield a positive test on a rapid test.”
“Right now, we’re looking at all of our data we've collected here at Emory, and we're looking at vaccination status and even the timing of when the vaccination or booster was received, compared to the viral load we get with the PCR, compared to quantitative antigen testing and then compared to several of the rapid tests that we can get over the counter, really trying to answer that question.”
Q: How can community members participate in the RADx research?
A: “The whole goal here is to allow our community families to get access to testing easier and to do it all at once, do it for free, and also if they’re willing, to be test subjects to test new technologies,” Lam says.
Members of the community can now visit the RADx Executive Park COVID research site for free testing and to participate in the study. Testing can also be scheduled in advance through the ACME POCT online portal.
“We chose a place that was very close to the Children's hospital, but also close to Emory, and it really is a one-stop shop for entire families,” Lam explains. “Our Children's Healthcare of Atlanta clinical team will take care of the kids, and our Emory team will take care of the adults, and that's one major reason we want to do this.”
“We are also centralizing all of our resources so we can be more nimble, and also allow us to test technologies that are very different — maybe even technologies that are meant in the clinical laboratory but have some novel aspect to them, and might not even be a PCR test, might not even be a rapid test,” he adds. “So, having that capability to be nimble and really prepare for the next type of pandemic, and also use this place to look for and assess point-of-care diagnostics for other diseases. Having this infrastructure there allows us to do all that.”
Q: How will these technologies continue to improve?
A: “What the pandemic has really shown us is that point-of-care and home-based testing is here to stay and will only ramp up,” Lam says.
He notes that technology developers are now working to combine rapid tests for respiratory illnesses, such as COVID-19 and influenza or RSV. There are also new technologies on the horizon, such as breath tests for COVID-19 and other diseases.
“There's starting to be this blurring of medical diagnostics with consumer products, and we here at Emory will play a major role there,” Lam says. “In fact, we're starting a new diagnostics center that will really take all the best of what we've done for RADx, but help our local technology developers here within our own Atlanta ecosystem accelerate their technology through the translational pipeline. So, that's something we're really excited about, and I think will be good not only for our institutions, but our local community, as well.”