An At-Home Contagiousness Test for COVID-19 Already Exists. Why Can’t We Use It?
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
You're lying in bed late at night, the foggy swirl of the pandemic's 8th month just beginning to fall behind you, when you detect a slight tickle at the back of your throat.
"If half of people choose to use these tests every other day, then we can stop transmission faster than a vaccine can."
Suddenly fully awake, a jolt of panicked electricity races through your body. Has COVID-19 come for you? In the U.S., answering this simple question is incredibly difficult.
Now, you might have to wait for hours in line in your car to get a test for $100, only to find out your result 10-14 days later -- much too late to matter in stopping an outbreak. Due to such obstacles, a recent report in JAMA Internal Medicine estimated that 9 out of 10 infections in the U.S. are being missed.
But what if you could use a paper strip in the privacy of your own home, like a pregnancy test, and find out if you are contagious in real time?
e25 Bio, a small company in Cambridge, Mass., has already created such a test and it has been sitting on a lab bench, inaccessible, since April. It is an antigen test, which looks for proteins on the outside of a virus, and can deliver results in about 15 minutes. Also like an over-the-counter pregnancy test, e25 envisions its paper strips as a public health screening tool, rather than a definitive diagnostic test. People who see a positive result would be encouraged to then seek out a physician-administered, gold-standard diagnostic test: the more sensitive PCR.
Typically, hospitals and other health facilities rely on PCR tests to diagnose viruses. This test can detect small traces of genetic material that a virus leaves behind in the human body, which tells a clinician that the patient is either actively infected with or recently cleared that virus. PCR is quite sensitive, meaning that it is able to detect the presence of a virus' genetic material very accurately.
But although PCR is the gold-standard for diagnostics, it's also the most labor-intensive way to test for a virus and takes a relatively long time to produce results. That's not a good match for stopping super-spreader events during an unchecked pandemic. PCR is also not great at identifying the infected people when they are most at risk of potentially transmitting the virus to others.
That's because the viral threshold at which PCR can detect a positive result is so low, that it's actually too sensitive for the purposes of telling whether someone is contagious.
"The majority of time someone is PCR positive, those [genetic] remnants do not indicate transmissible virus," epidemiologist Michael Mina recently Tweeted. "They indicate remnants of a recently cleared infection."
To stop the chain of transmission for COVID-19, he says, "We need a more accurate test than PCR, that turns positive when someone is able to transmit."
In other words, we need a test that is better at detecting whether a person is contagious, as opposed to whether a small amount of virus can be detected in their nose or saliva. This kind of test is especially critical given the research showing that asymptomatic and pre-symptomatic people have high viral loads and are spreading the virus undetected.
The critical question for contagiousness testing, then, is how big a dose of SARS-CoV-2, the virus that causes COVID, does it take to infect most people? Researchers are still actively trying to answer this. As Angela Rasmussen, a coronavirus expert at Columbia University, told STAT: "We don't know the amount that is required to cause an infection, but it seems that it's probably not a really, really small amount, like measles."
Amesh Adalja, an infectious disease physician and a senior scholar at the Johns Hopkins University Center for Health Security, told LeapsMag: "It's still unclear what viral load is associated with contagiousness but it is biologically plausible that higher viral loads, in general, are associated with more efficient transmission especially in symptomatic individuals. In those without symptoms, however, the same relationship may not hold and this may be one of the reasons young children, despite their high viral loads, are not driving outbreaks."
"Antigen tests work best when there's high viral loads. They're catching people who are super spreaders."
Mina and colleagues estimate that widespread use of weekly cheap, rapid tests that are 100 times less sensitive than PCR tests would prevent outbreaks -- as long as the people who are positive self-isolate.
So why can't we buy e25Bio's test at a drugstore right now? Ironically, it's barred for the very reason that it's useful in the first place: Because it is not sensitive enough to satisfy the U.S. Food and Drug Administration, according to the company.
"We're ready to go," says Carlos-Henri Ferré, senior associate of operations and communications at e25. "We've applied to FDA, and now it's in their hands."
The problem, he said, is that the FDA is evaluating applications for antigen tests based on criteria for assessing diagnostics, like PCR, even when the tests serve a different purpose -- as a screening tool.
"Antigen tests work best when there's high viral loads," Ferré says. "They're catching people who are super spreaders, that are capable of continuing the spread of disease … FDA criteria is for diagnostics and not this."
FDA released guidance on July 29th -- 140 days into the pandemic -- recommending that at-home tests should perform with at least 80 percent sensitivity if ordered by prescription, and at least 90 percent sensitivity if purchased over the counter. "The danger of a false negative result is that it can contribute to the spread of COVID-19," according to an FDA spokesperson. "However, oversight of a health care professional who reviews the results, in combination with the patient's symptoms and uses their clinical judgment to recommend additional testing, if needed, among other things, can help mitigate some risks."
Crucially, the 90 percent sensitivity recommendation is judged upon comparison to PCR tests, meaning that if a PCR test is able to detect virus in 100 samples, the at-home antigen test would need to detect virus in at least 90 of those samples. Since antigen tests only detect high viral loads, frustrated critics like Mina say that such guidance is "unreasonable."
"The FDA at this moment is not understanding the true potential for wide-scale frequent testing. In some ways this is not their fault," Mina told LeapsMag. "The FDA does not have any remit to evaluate tests that fall outside of medical diagnostic testing. The proposal I have put forth is not about diagnostic testing (leave that for symptomatic cases reporting to their physician and getting PCR tests)....Daily rapid tests are not about diagnosing people and they are not about public health surveillance and they are not about passports to go to school, out to dinner or into the office. They are about reducing population-level transmission given a similar approach as vaccines."
A reasonable standard, he added, would be to follow the World Health Organization's Target Product Profiles, which are documents to help developers build desirable and minimally acceptable testing products. "A decent limit," Mina says, "is a 70% or 80% sensitivity (if they truly require sensitivity as a metric) to detect virus at Ct values less than 25. This coincides with detection of the most transmissible people, which is important."
(A Ct value is a type of measurement that corresponds inversely to the amount of viral load in a given sample. Researchers have found that Ct values of 13-17 indicate high viral load, whereas Ct values greater than 34 indicate a lack of infectious virus.)
"We believe this should be an at-home test, but [if FDA approval comes through] the first rollout is to do this in laboratories, hospitals, and clinics."
"We believe that population screening devices have an immediate place and use in helping beat the virus," says Ferré. "You can have a significant impact even with a test at 60% sensitivity if you are testing frequently."
When presented with criticism of its recommendations, the FDA indicated that it will not automatically deny any at-home test that fails to meet the 90 percent sensitivity guidance.
"FDA is always open to alternative proposals from developers, including strategies for serial testing with less sensitive tests," a spokesperson wrote in a statement. "For example, it is possible that overall sensitivity of the strategy could be considered cumulatively rather than based on one-time testing….In the case of a manufacturer with an at-home test that can only detect people with COVID-19 when they have a high viral load, we encourage them to talk with us so we can better understand their test, how they propose to use it, and the validation data they have collected to support that use."
However, the FDA's actions so far conflict with its stated openness. e25 ended up adding a step to the protocol in order to better meet FDA standards for sensitivity, but that extra step—sending samples to a laboratory for results—will undercut the test's ability to work as an at-home screening tool.
"We believe this should be an at-home test, but [if FDA approval comes through] the first rollout is to do this in laboratories, hospitals, and clinics," Ferré says.
According to the FDA, no test developers have approached them with a request for an emergency use authorization that proposes an alternate testing paradigm, such as serial testing, to mitigate test sensitivity below 80 percent.
From a scientific perspective, antigen tests like e25Bio's are not the only horse in the race for a simple rapid test with potential for at-home use. CRISPR technology has long been touted as fertile ground for diagnostics, and in an eerily prescient interview with LeapsMag in November, CRISPR pioneer Feng Zhang spoke of its potential application as an at-home diagnostic for an infectious disease specifically.
"I think in the long run it will be great to see this for, say, at-home disease testing, for influenza and other sorts of important public health [concerns]," he said in the fall. "To be able to get a readout at home, people can potentially quarantine themselves rather than traveling to a hospital and then carrying the risk of spreading that disease to other people as they get to the clinic."
Zhang's company Sherlock Biosciences is now working on scaled-up manufacturing of a test to detect SARS CoV-2. Mammoth Biosciences, which secured funding from the National Institutes of Health's Rapid Acceleration of Diagnostics program, is also working on a CRISPR diagnostic for SARS CoV-2. Both would check the box for rapid testing, but so far not for at-home testing, as they would also require laboratory infrastructure to provide results.
If any at-home tests can clear the regulatory hurdles, they would also need to be manufactured on a large scale and be cheap enough to entice people to actually use them. In the world of at-home diagnostics, pregnancy tests have become the sole mainstream victor because they're simple to use, small to carry, easy to interpret, and costs about seven or eight dollars at any ubiquitous store, like Target or Walmart. By comparison, the at-home COVID collection tests that don't even offer diagnostics—you send away your sample to an external lab—all cost over $100 to take just one time.
For the time being, the only available diagnostics for COVID require a lab or an expensive dedicated machine to process. This disconnect could prolong the world's worst health crisis in a century.
"Daily rapid tests have enormous potential to sever transmission chains and create herd effects similar to herd immunity," Mina says. "We all recognize that vaccines and infections can result in herd immunity when something around half of people are no longer susceptible.
"The same thing exists with these tests. These are the intervention to stop the virus. If half of people choose to use these tests every other day, then we can stop transmission faster than a vaccine can. The technology exists, the theory and mathematics back it up, the epidemiology is sound. There is no reason we are not approaching this as strongly as we would be approaching vaccines."
--Additional reporting by Julia Sklar
Kira Peikoff was the editor-in-chief of Leaps.org from 2017 to 2021. As a journalist, her work has appeared in The New York Times, Newsweek, Nautilus, Popular Mechanics, The New York Academy of Sciences, and other outlets. She is also the author of four suspense novels that explore controversial issues arising from scientific innovation: Living Proof, No Time to Die, Die Again Tomorrow, and Mother Knows Best. Peikoff holds a B.A. in Journalism from New York University and an M.S. in Bioethics from Columbia University. She lives in New Jersey with her husband and two young sons. Follow her on Twitter @KiraPeikoff.
Some hospitals are pioneers in ditching plastic, turning green
This is part 2 of a three part series on a new generation of doctors leading the charge to make the health care industry more sustainable - for the benefit of their patients and the planet. Read part 1 here and part 3 here.
After graduating from her studies as an engineer, Nora Stroetzel ticked off the top item on her bucket list and traveled the world for a year. She loved remote places like the Indonesian rain forest she reached only by hiking for several days on foot, mountain villages in the Himalayas, and diving at reefs that were only accessible by local fishing boats.
“But no matter how far from civilization I ventured, one thing was already there: plastic,” Stroetzel says. “Plastic that would stay there for centuries, on 12,000 foot peaks and on beaches several hundred miles from the nearest city.” She saw “wild orangutans that could be lured by rustling plastic and hermit crabs that used plastic lids as dwellings instead of shells.”
While traveling she started volunteering for beach cleanups and helped build a recycling station in Indonesia. But the pivotal moment for her came after she returned to her hometown Kiel in Germany. “At the dentist, they gave me a plastic cup to rinse my mouth. I used it for maybe ten seconds before it was tossed out,” Stroetzel says. “That made me really angry.”
She decided to research alternatives for plastic in the medical sector and learned that cups could be reused and easily disinfected. All dentists routinely disinfect their tools anyway and, Stroetzel reasoned, it wouldn’t be too hard to extend that practice to cups.
It's a good example for how often plastic is used unnecessarily in medical practice, she says. The health care sector is the fifth biggest source of pollution and trash in industrialized countries. In the U.S., hospitals generate an estimated 6,000 tons of waste per day, including an average of 400 grams of plastic per patient per day, and this sector produces 8.5 percent of greenhouse gas emissions nationwide.
“Sustainable alternatives exist,” Stroetzel says, “but you have to painstakingly look for them; they are often not offered by the big manufacturers, and all of this takes way too much time [that] medical staff simply does not have during their hectic days.”
When Stroetzel spoke with medical staff in Germany, she found they were often frustrated by all of this waste, especially as they took care to avoid single-use plastic at home. Doctors in other countries share this frustration. In a recent poll, nine out of ten doctors in Germany said they’re aware of the urgency to find sustainable solutions in the health industry but don’t know how to achieve this goal.
After a year of researching more sustainable alternatives, Stroetzel founded a social enterprise startup called POP, short for Practice Without Plastic, together with IT expert Nicolai Niethe, to offer well-researched solutions. “Sustainable alternatives exist,” she says, “but you have to painstakingly look for them; they are often not offered by the big manufacturers, and all of this takes way too much time [that] medical staff simply does not have during their hectic days.”
In addition to reusable dentist cups, other good options for the heath care sector include washable N95 face masks and gloves made from nitrile, which waste less water and energy in their production. But Stroetzel admits that truly making a medical facility more sustainable is a complex task. “This includes negotiating with manufacturers who often package medical materials in double and triple layers of extra plastic.”
While initiatives such as Stroetzel’s provide much needed information, other experts reason that a wholesale rethinking of healthcare is needed. Voluntary action won’t be enough, and government should set the right example. Kari Nadeau, a Stanford physician who has spent 30 years researching the effects of environmental pollution on the immune system, and Kenneth Kizer, the former undersecretary for health in the U.S. Department of Veterans Affairs, wrote in JAMA last year that the medical industry and federal agencies that provide health care should be required to measure and make public their carbon footprints. “Government health systems do not disclose these data (and very rarely do private health care organizations), unlike more than 90% of the Standard & Poor’s top 500 companies and many nongovernment entities," they explained. "This could constitute a substantial step toward better equipping health professionals to confront climate change and other planetary health problems.”
Compared to the U.K., the U.S. healthcare industry lags behind in terms of measuring and managing its carbon footprint, and hospitals are the second highest energy user of any sector in the U.S.
Kizer and Nadeau look to the U.K. National Health Service (NHS), which created a Sustainable Development Unit in 2008 and began that year to conduct assessments of the NHS’s carbon footprint. The NHS also identified its biggest culprits: Of the 2019 footprint, with emissions totaling 25 megatons of carbon dioxide equivalent, 62 percent came from the supply chain, 24 percent from the direct delivery of care, 10 percent from staff commute and patient and visitor travel, and 4 percent from private health and care services commissioned by the NHS. From 1990 to 2019, the NHS has reduced its emission of carbon dioxide equivalents by 26 percent, mostly due to the switch to renewable energy for heat and power. Meanwhile, the NHS has encouraged health clinics in the U.K. to install wind generators or photovoltaics that convert light to electricity -- relatively quick ways to decarbonize buildings in the health sector.
Compared to the U.K., the U.S. healthcare industry lags behind in terms of measuring and managing its carbon footprint, and hospitals are the second highest energy user of any sector in the U.S. “We are already seeing patients with symptoms from climate change, such as worsened respiratory symptoms from increased wildfires and poor air quality in California,” write Thomas B. Newman, a pediatrist at the University of California, San Francisco, and UCSF clinical research coordinator Daisy Valdivieso. “Because of the enormous health threat posed by climate change, health professionals should mobilize support for climate mitigation and adaptation efforts.” They believe “the most direct place to start is to approach the low-lying fruit: reducing healthcare waste and overuse.”
In addition to resulting in waste, the plastic in hospitals ultimately harms patients, who may be even more vulnerable to the effects due to their health conditions. Microplastics have been detected in most humans, and on average, a human ingests five grams of microplastic per week. Newman and Valdivieso refer to the American Board of Internal Medicine's Choosing Wisely program as one of many initiatives that identify and publicize options for “safely doing less” as a strategy to reduce unnecessary healthcare practices, and in turn, reduce cost, resource use, and ultimately reduce medical harm.
A few U.S. clinics are pioneers in transitioning to clean energy sources. In Wisconsin, the nonprofit Gundersen Health network became the first hospital to cut its reliance on petroleum by switching to locally produced green energy in 2015, and it saved $1.2 million per year in the process. Kaiser Permanente eliminated its 800,000 ton carbon footprint through energy efficiency and purchasing carbon offsets, reaching a balance between carbon emissions and removing carbon from the atmosphere in 2020, the first U.S. health system to do so.
Cleveland Clinic has pledged to join Kaiser in becoming carbon neutral by 2027. Realizing that 80 percent of its 2008 carbon emissions came from electricity consumption, the Clinic started switching to renewable energy and installing solar panels, and it has invested in researching recyclable products and packaging. The Clinic’s sustainability report outlines several strategies for producing less waste, such as reusing cases for sterilizing instruments, cutting back on materials that can’t be recycled, and putting pressure on vendors to reduce product packaging.
The Charité Berlin, Europe’s biggest university hospital, has also announced its goal to become carbon neutral. Its sustainability managers have begun to identify the biggest carbon culprits in its operations. “We’ve already reduced CO2 emissions by 21 percent since 2016,” says Simon Batt-Nauerz, the director of infrastructure and sustainability.
The hospital still emits 100,000 tons of CO2 every year, as much as a city with 10,000 residents, but it’s making progress through ride share and bicycle programs for its staff of 20,000 employees, who can get their bikes repaired for free in one of the Charité-operated bike workshops. Another program targets doctors’ and nurses’ scrubs, which cause more than 200 tons of CO2 during manufacturing and cleaning. The staff is currently testing lighter, more sustainable scrubs made from recycled cellulose that is grown regionally and requires 80 percent less land use and 30 percent less water.
The Charité hospital in Berlin still emits 100,000 tons of CO2 every year, but it’s making progress through ride share and bicycle programs for its staff of 20,000 employees.
Wiebke Peitz | Specific to Charité
Anesthesiologist Susanne Koch spearheads sustainability efforts in anesthesiology at the Charité. She says that up to a third of hospital waste comes from surgery rooms. To reduce medical waste, she recommends what she calls the 5 Rs: Reduce, Reuse, Recycle, Rethink, Research. “In medicine, people don’t question the use of plastic because of safety concerns,” she says. “Nobody wants to be sued because something is reused. However, it is possible to reduce plastic and other materials safely.”
For instance, she says, typical surgery kits are single-use and contain more supplies than are actually needed, and the entire kit is routinely thrown out after the surgery. “Up to 20 percent of materials in a surgery room aren’t used but will be discarded,” Koch says. One solution could be smaller kits, she explains, and another would be to recycle the plastic. Another example is breathing tubes. “When they became scarce during the pandemic, studies showed that they can be used seven days instead of 24 hours without increased bacteria load when we change the filters regularly,” Koch says, and wonders, “What else can we reuse?”
In the Netherlands, TU Delft researchers Tim Horeman and Bart van Straten designed a method to melt down the blue polypropylene wrapping paper that keeps medical instruments sterile, so that the material can be turned it into new medical devices. Currently, more than a million kilos of the blue paper are used in Dutch hospitals every year. A growing number of Dutch hospitals are adopting this approach.
Another common practice that’s ripe for improvement is the use of a certain plastic, called PVC, in hospital equipment such as blood bags, tubes and masks. Because of its toxic components, PVC is almost never recycled in the U.S., but University of Michigan researchers Danielle Fagnani and Anne McNeil have discovered a chemical process that can break it down into material that could be incorporated back into production. This could be a step toward a circular economy “that accounts for resource inputs and emissions throughout a product’s life cycle, including extraction of raw materials, manufacturing, transport, use and reuse, and disposal,” as medical experts have proposed. “It’s a failure of humanity to have created these amazing materials which have improved our lives in many ways, but at the same time to be so shortsighted that we didn’t think about what to do with the waste,” McNeil said in a press release.
Susanne Koch puts it more succinctly: “What’s the point if we save patients while killing the planet?”
The Friday Five: A surprising health benefit for people who have kids
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
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Here are the promising studies covered in this week's Friday Five:
- Kids stressing you out? They could be protecting your health.
- A new device unlocks the heart's secrets
- Super-ager gene transplants
- Surgeons could 3D print your organs before operations
- A skull cap looks into the brain like an fMRI