The Biden administration’s recent investment of $230 million to expedite rapid production of the Ellume home Covid-19 test represents an audacious step forward in mitigating the pandemic.
Some experts have criticized it as a “waste of money” because this kit costs more than other alternatives and because of the timing of the investment. I believe the test is worth the extra cost, due to its connectivity and the types of research it enables, though all of these tests need to be evaluated against the other options.
Throughout the pandemic, public health officials have struggled to demonstrate the value and importance of measures such as mask wearing, social distancing, and vaccines. The ultimate result has been public skepticism, poor uptake of helpful interventions, and even outrageous conspiracy theories. We must learn from these missteps and design interventions that can be measured quickly and precisely.
Ellume joins the Lucira Covid-19 All-In-One Test Kit as tests the FDA has approved for use under emergency use authorizations. A third home test, made by Quidel, is currently under FDA review, and more are underway. Fully at-home tests quickly tell users if they have been infected by SARS-CoV-2, the virus that causes Covid-19, unlike tests in which users collect samples at home then ship them to the manufacturer or a lab for analysis.
The accuracy and limits of detection for the three fully at-home Covid-19 are similar. The big difference is how the results are delivered — and to whom.
All three kits use a nasal swab to collect a sample to test and deliver results in 15 to 30 minutes. With the Lucira test, the user places the loaded swab into a testing device, which displays the result on an LCD screen. The Quidel test displays the result in much the same way as home pregnancy tests. The Ellume kit is the most automated of the three. Its sample-processing device requires a Bluetooth connection with a smartphone. Users download an app, connect it to the kit, watch a detailed instructional video, collect their sample, and put it in the analyzer. It then processes the sample and gives the user the result via the app (or email, if desired). At the same time, it transmits the result to the kit manufacturer along with the kit’s unique ID number and limited data, such as date of birth and ZIP code, about the user.
This workflow is highly useful to public health officials, and the ability to report results directly to health authorities is explicitly listed within the emergency use authorization. Use of the Ellume kit will generate a highly detailed view of where these kits are being used and what the test results are, affording granular, actionable data to support health interventions. The video that’s part of the kit should limit complexity and user error.
With the Lucira and Quidel tests, and others without network connectivity, there is no automated data collection and no way to know when or if a purchased kit has been used. The only way to measure the effects of home testing via such kits would be through some form of facilitated voluntary reporting, regional surveillance of kit sales and hospitalizations, testing for coronavirus concentrations in wastewater, or other indirect measures. There is also no way to know the result of each kit or any way to associate the result of any given kit with any individual or any community.
There are tradeoffs, however, some of which place digitally connected tests on the challenging side of a growing digital divide. The Ellume test requires the user to have a smartphone and to use it to share personal health information with the test’s manufacturer. Such data sharing is not required by other kits, which means that socio-economic issues such as price, privacy preferences, owning a smartphone, and internet access, as well as the concerns of underserved populations, must be taken into consideration when evaluating the effectiveness of these tests as pandemic interventions.
Given the lingering ambiguity regarding the value of rapid Covid-19-testing technologies, unanswered questions about the performance of these tests in the home setting amplifies the uncertainty. While there is no debate that unlimited testing capacity is desirable in fighting the outbreak, large mass-testing experiments, such as those performed in Slovakia and in Liverpool, have generated significant controversy and raised more questions than they answered.
It’s also possible that home test kits will be misused or misconstrued, as when a user derives a false sense of confidence following a negative test result despite warnings that a negative result does not mean that there is no risk that the individual is infected or contagious.
It must also be noted that emergency use authorizations often afford a temporary relaxation of manufacturing quality and inspection requirements in the interests of speeding the delivery of needed therapeutics or diagnostics to consumers. As manufacturers rush to deliver millions of these tests, there’s no assurance that quality won’t slip.
Although critics of the decision to underwrite the Ellume kit with substantial federal investment make some solid points about cost and complexity, from the standpoint of generating evidence on the effectiveness of home Covid-19 testing I believe that the Biden administration has made the right choice under the circumstances. By selecting a digital, internet-enabled option, public health experts will be able to take advantage of a greatly enhanced capability to assess the usefulness of home testing during the pandemic than are possible with cheaper options — options that potentially offer more privacy but provide far less opportunity for detailed assessment of the impact of home testing as a public health intervention.
Debate about the utility of home Covid-19 testing will persist until the number of knowns exceed the number of unknowns. By investing in a home testing platform that automates data collection and reporting, the Biden administration has given us a head start in understanding the uptake, utility, and eventually the public good of these emerging technologies.
Eric D. Perakslis is a researcher and the chief science and digital officer at the Duke Clinical Research Institute, a faculty member in population health sciences at Duke University School of Medicine, and a lecturer in biomedical informatics at Harvard Medical School.