Dr. Bertalan Mesko
In January of this year, oblivious of the fact that we were about to engage in a twisted round of real-life Jumanji, we released our annual digital health trends e-book. Among one of our 12 forecasts for 2020 was that at-home blood tests would gain traction and become the new direct-to-consumer DNA testing in terms of adoption and availability. While the pandemic threw everyone off guard and messed up regular forecasts, we might have been onto something with our predicted trend.
With the need to limit physical contact and trace COVID-positive individuals rapidly, public health authorities worldwide are finding rapid, point-of-care (POC) tests for the novel coronavirus increasingly attractive. Whether it’s for testing antibodies or antigens, regulatory authorities are issuing approvals for such kits so as to boost testing capacities without the need of neither specialised equipment nor a lab.
Approvals are limited to kits for use by healthcare workers for now; but several companies are working on at-home rapid tests, and could soon follow suit in gaining approvals. Indeed, this adoption will not remain confined to COVID-19 tests either; rather, it will also extend to at-home lab tests for a quick analysis for general checkups and other ailments, despite previous setbacks.
While the pandemic boosted the adoption of rapid tests, this adoption was not immediate. From accuracy issues to uncertainties about the virus itself, rapid coronavirus tests have evolved these last months to offer a more reliable testing method.
In this article, we go through how these tests work, picture the timeline of their evolution and contemplate the potentials they hold for the future.
What is a rapid COVID test and how does it work?
Until now, the standard for COVID-19 testing has revolved around two main methods: molecular testing and antibody testing. The former involves the iconic nasal or throat swab sampling to check for the presence of the virus itself. This molecular testing technique is known as reverse transcription-polymerase chain reaction (RT-PCR). It detects viral genetic material from the sample.
Antibody testing involves checking for the presence of antibodies that one’s immune system develops in response to the virus. For this purpose, blood samples from a finger prick undergo analysis with a serology test.
However, both PCR and traditional serology tests require trained personnel and specific equipment to perform. Additionally, depending on the proximity of the testing lab, they can take hours or days to provide a result.
On the other hand, rapid COVID tests, as the name suggests, offer a quick diagnostic method to determine if someone is infected with SARS-CoV-2; as quickly as 15 minutes. Some come in kits that detect antibodies faster through specialised, portable detection devices like the Abbot ID NOW. Others function by applying a sample of bodily fluid onto a special paper strip which is able to detect antigens, or viral proteins, on the spot. Such rapid tests are much easier, faster and cheaper to perform than the standard tests; without the need for sending back to a central lab for testing.
The potential of expanding access to tests is putting rapid tests in a favorable light. In late August, the FDA granted one such fast antigen testing kit from Abbott Laboratories emergency-use approval. Their BinaxNOW rapid COVID-19 nasal swab test costs only $5 and gives a result within 15 minutes. The U.S. government purchased 150 million of these to put testing on the fast track. In September, the FDA issued an emergency use authorisation for the first antibody POC test for COVID-19. This Assure COVID-19 IgG/IgM Rapid Test Device works by using fingerstick blood samples. For now, these approved POC tests are limited for use by healthcare professionals.
Are they reliable?
The main issue that comes up when rapid tests come into play is that of reliability. Antibodies take about two weeks after a SARS-CoV-2 infection to become detectable. Testing before that time will miss detection and serology tests don’t detect an active infection. Antigen tests for their part detect the viral proteins mostly at the peak of an infection; when virus levels in the body are also peaking. This can indicate when someone has the most potential to infect others. But as of now, there’s no clear viral load threshold demarcating when someone is no longer contagious.
On the other hand, when administered properly, high-sensitivity PCR tests have a nearly 100% accuracy in detecting infected people; even if minute amounts of the virus are present. The ability of Abbott’s quick antigen assay to correctly detect those infected drops to 75% if the test is performed a week after symptoms show. Experts worry that rapid tests will miss infectious persons and lead to spikes in cases; after all, it only takes one infected person to initiate an outbreak.
Nevertheless, rapid tests can be a game changer; in particular when there are a lot of cases and little access to equipped testing facilities. At the beginning of April, India tested only some 150 000 people; one of the lowest testing rates per capita worldwide. Fast-forward a few months to August and the country ran over a million coronavirus tests in a single day. This boost in testing capacity was possible since Indian authorities adopted antigen assays. And since they help identify individuals most likely to spread the infection, appropriate measures to isolate them can be taken in a timely fashion.
To further ensure that no positive cases evade detection from rapid tests, the FDA suggests that negative results “may need to be confirmed with a lab test in some cases, such as when patients have coronavirus-like symptoms.” This can add a layer of certainty to rapid tests in cases of doubt.
The rapid evolution of rapid COVID tests
The quick diagnostic prowess of rapid tests interested public health authorities even at the beginning of the pandemic. But before getting widespread approval, authorities came across issues as those tests were starting to roll out early on.
Back in April, India cancelled some half a million coronavirus rapid testing kits from China. These could detect antibodies in blood samples and deliver a result within 30 minutes. But after reports of these kits showed an accuracy rate of only 5%, authorities axed orders for those rapid tests.
The next month, in May, the FDA advised caution about the Abbott ID Now rapid test. This was because it could miss up to 48% of infections. In the same month, the U.S.-based regulatory authority indicated a list of COVID-19 antibody tests, including a rapid kit by BioMedomics, that should be removed from the market. These tests were sold under former, looser COVID-19 diagnostics policy – which could bypass FDA review.
Hope around rapid tests renewed in later months as health authorities employed them on a larger scale. For instance, Thailand’s main international airport started to use such kits in July as the country opened up to groups of foreigners. Rapid tests saw real success from August, when more tests gained approval from the FDA as mentioned above. Then in late September, the WHO announced that a $5 rapid antigen test from Abbott and SD Biosensor will become available to 133 low- and middle-income countries for faster detection of the virus. This marked the first Emergency Use Listing approval from the WHO for a COVID-19 antigen rapid diagnostic testing (RDT).
“This will enable the expansion of testing, particularly in hard-to-reach areas that do not have laboratory facilities or enough trained health workers to carry out tests,” said the WHO Director General Tedros Adhanom Ghebreyesus. The health authority also mentioned that “several rapid, point-of-care antigen tests are being assessed by WHO for Emergency Use Listing”.Approval of the first RDT within 8 months of the virus’ identification was a first. In comparison, the first RDT for HIV took almost 5 years to develop.
As easy as a pregnancy test?
This rapid rate of approvals from regulatory authorities also attest to a faster rate of innovation in the face of a global challenge; pushing companies to develop more accurate tests. And this rapid evolution could usher the boom in at-home lab tests in the near future. Already companies have developed at-home COVID-19 paper-strip antigen tests. But emergency use approvals from drug regulators haven’t been issued for these tests yet. However, it’s just a matter of time.
“We don’t have a lot of real-life experience with these tests, and a lot of the validations have only been done in the laboratory,” says Edsel Salvaña, an infectious-diseases expert advising Philippine officials on rapid testing. As even approved POC tests give more results, the same companies behind them could repurpose their kits for at-home use to check for COVID-19 or other illnesses.
For example, a rapid, bedside test from DnaNudge, an Imperial College London start-up, showed 94% sensitivity and 100% specificity; signifying a high accuracy level with low false negatives and no false positives. The test is in development to enable simultaneous detection of COVID-19, influenza and respiratory syncytial virus. In the near future, these tests could become as easy and accessible as pregnancy tests; cheap, simple enough to use at home, accurate and not requiring any technical knowledge. “You just spit into a tube, put a piece of paper in it and you get the result within minutes,” explains Martin Burke, a chemist at the University of Illinois at Urbana-Champaign, who is co-developing rapid tests. “Testing should become a part of life: in the morning you take your cereals, your vitamins, and you quickly check your status,” he says.
The future lab is at home but regulated
Of course, with easily accessible at-home tests, new issues arise. People could ask someone else to take their test; or they won’t report positive cases of infection so that they can continue to work. And if those tests give a false negative result, that person would have a false sense of security; and could even not take public health measures as seriously.
Such issues aren’t applicable for only COVID-19, but also for other at-home lab tests that will keep sprouting in the future. As such, regulators should pay closer attention to the potentials of rapid at-home lab tests as they are undoubtedly going to be increasingly put to use.
Indeed, amidst the pandemic, COVID-related point-of-care tests experienced a uniquely quick evolution, which truly paves the way for at-home lab tests. It is a sector ripe for disruption that has yet to be penetrated by advanced technologies. And with the enhanced access to care that these technologies offer, additional concerns over their use will emerge that have to be tackled by policymakers in a timely manner.
Dr. Bertalan Mesko, PhD is The Medical Futurist and Director of The Medical Futurist Institute analyzing how science fiction technologies can become reality in medicine and healthcare. As a geek physician with a PhD in genomics, he is a keynote speaker and an Amazon Top 100 author.
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