Most of us are used to a certain routine by now for when we feel sick. If we feel a little feverish, or start coughing, we reach for an at-home testing kit that tells us, with a quick nasal swab and after 15 minutes, whether we have COVID-19 or not. The tests are easy to use, and for now, paid for by insurance if you’ve got it. If you don’t have insurance, you can still get the kits for free from some community health centers.
If the test shows that you’re positive, you know to stay home and mask up, and ask your doctor about taking antiviral medications that can minimize the symptoms and keep you from getting seriously ill. If you’re a parent and testing your kids, the kits can signal when to keep them at home from school.
It’s a win-win, since knowing your status means you can protect not only yourself but your community by not spreading the virus when you stay home and get treated.
COVID-19 has set a new standard of expectations for testing, and knowing whether you’re sick, that is starting to make the way the U.S. traditionally manages winter season diseases look archaic. Why don’t we have the same self-tests for other common illnesses that spread during the colder months—such as flu and RSV? Each year flu leads to between 300,000 and 800,000 hospitalizations in the U.S., while RSV sends up to 80,000 young children under five years old to the hospital annually.
“The pandemic shifted people’s expectations,” says Dr. Michael Mina, chief science officer at eMed, a digital health company that offers at-home testing and telemedicine options to help with those tests for a range of illnesses. “It’s driving people to ask, ‘why do I need to go to the doctor when COVID-19 testing has shown me that it’s totally safe and okay for me to [use self-tests to determine] if I’m positive for a respiratory illness?’”
Until the pandemic hit, at-home testing was a health trend struggling for respect. While convenient, the medical community and health regulators at the Food and Drug Administration (FDA) weren’t convinced that people could reliably test themselves at home for things like flu, and interpret the results accurately. Decades earlier, home pregnancy test kits battled through similar validation issues, as health care experts raised concerns about releasing a test that wasn’t always completely accurate and about the need to educate women about interpreting the results. Ultimately, regulators decided that the level of uncertainty was an acceptable tradeoff for arming women with knowledge about their pregnancy status and the tests became available in 1978 over the counter.
With similar reasoning, and this time driven by the urgent need during the pandemic to limit the spread of SARS-CoV-2, the FDA authorized the first at-home rapid tests for COVID-19 in spring 2020. Millions of people have since tested themselves or their children, without a medical professional, effectively and responsibly. “The COVID-19 pandemic led to a shift in empowering citizens with the ability to test themselves for respiratory infections,” says Dr. Chaz Langelier, associate professor of medicine in the division of infectious diseases at University of California San Francisco. “The average person in the U.S. now has a working knowledge of the public health implications of respiratory infections on a level that wasn’t there pre-pandemic.”
The barriers to self-testing
Studies conducted on at-home COVID-19 tests showed that people don’t need a medical degree to insert a swab up their nose, swirl it around, and then insert the swab in a pre-made solution and read the resulting lines. In fact, that technology is essentially the same one that doctors and nurses use in doctors’ offices, emergency rooms and health centers to test for influenza, RSV, and strep. “The average person thinks that when they go to the doctor and he or she uses a rapid strep or flu test, that the doctor is doing something complicated behind the scenes,” says Mina. “But no, it’s just the same swabbing of the nose or throat and the same lateral flow antigen test [as in the home kits]. The COVID-19 self tests have demystified how some of these medical tests are performed. And opened to door to people asking, ‘why don’t I have access to that?’”
The reason they don’t yet has to do with a number of factors, from cultural bias to the economics of the flu-testing market. The medical community has historically been reluctant to entrust self-tests in the hands of the public because of concerns about how well the people without medical expertise can collect the samples and perform the chemical reaction required to detect the presence of a virus or bacteria. But streamlined ways to contain reagents and present them in a straightforward way, such as the easy-to-use COVID-19 test kits, have made the process nearly mistake-proof, Mina says.
While that may be true of the COVID-19 self tests, the self-tests for flu that are still being developed aren’t quite there yet. Doctors have relied for years on so-called point-of-care testing that provides results within minutes about whether their patients have flu, but they have also known that the false negative rate of these tests can range up to 40%. “You trade accuracy for speed,” says Dr. Lisa Maragakis, professor of medicine at Johns Hopkins University School of Medicine. Such rapid antigen tests, which pick up proteins made by viruses like SARS-CoV-2 or influenza, are relatively good at detecting people who are positive, leading to low false positive rates, but a negative result doesn’t always mean the person is free and clear. Doctors take other factors into consideration, such as the patient’s symptoms and exposures, when interpreting negative results. And if needed, they repeat the test to confirm the result.
To date, another reason at-home tests for viruses like influenza haven’t filled pharmacy shelves has been the relatively low demand for them. Most doctors don’t order flu tests for every patient who complains of fever and fatigue during flu season. They make an educated guess based on their patients’ symptoms that with influenza viruses circulating widely during the winter months, those people most likely have the flu—and most treatments, such as Tamiflu, are relatively safe but need to be started as soon as possible after symptoms appear in order to be effective. And manufacturers decided that if there wasn’t great uptake of flu tests in the medical community, then for the same reasons, there likely wouldn’t be demand for at-home versions either. Most people with flu-like symptoms would assume they have the flu and wouldn’t feel the need to test themselves to confirm that.
But COVID-19 changed that. Since COVID-19 causes similar symptoms to flu of fever, muscle aches and fatigue, doctors can no longer safely assume their patients are infected with influenza. Now, it’s important to distinguish the two infections because they have different antiviral treatments. Having self-tests for influenza as well as SARS-CoV-2 would help to differentiate them and get people started on the right medications for their respective infections more quickly. “Clinicians are inclined to trust a positive test in the scenario of a patient who also has symptoms consistent with disease,” says Maragakis. “We see that with COVID-19 that doctors are incorporating results of home tests more and more into their clinical decision-making.”
The promise of self-testing
At-home self testing could streamline the entire journey from sick patients to testing to treatments, says Mina. Especially if the convenience of DIY testing is combined with an easy way to access medical advice and treatments via telemedicine. For example, looping in a doctor, nurse, or qualified health care expert using telemedicine after people test themselves can help them interpret their results and provide them with prescription treatments, all from their own home. Some COVID-19 self-test kits already provide this connection, with a link or number that helps the test-taker connect to a telemedicine professional to validate results to document their COVID-19 status for travel or other purposes. It gives people the privacy and convenience of testing themselves, while also supporting that testing with any medical service they might need. “Tying these tests to care is a really smart thing,” says Mina. “We need to give patients the tools to test themselves, but also give them the entire package of health care just like they would receive if they went to the doctor for a test.”
How close are we to having at-home flu tests?
The FDA has set strict criteria for at-home tests, and the false negative rate for rapid antigen tests for influenza has been a stumbling block. Manufacturers are trying to address that concern by offering molecular tests that pick up viral genes rather than rapid-antigen tests, which identify the proteins that viruses make—these molecular tests are generally more accurate.
There are, so far, no FDA-approved at-home tests for influenza. And the FDA has approved two molecular at-home tests for COVID-19, made by Lucira and Cue Health. They are more expensive (Lucira’s test is $29, and Cue offers three tests for $195) than the rapid antigen tests (which retail for around $24 for two tests) because they require more sophisticated reactions—although all of them are reimbursed by insurance. Both Lucira and Cue have developed a version of their COVID-19 self tests that also pick up influenza infection, and have requested authorization from the FDA to make these combination tests available without a prescription. The agency has not made a decision yet.
Even if these molecular tests are authorized by the FDA, their high cost mean that it’s likely that rapid antigen tests for flu would still have a place, despite being less accurate. That’s because antigen tests are still relatively reliable in picking up viral proteins, which are typically at high levels in people when they first get sick—the point in time at which they are most likely to test themselves. “Especially at the beginning stages of infection, you don’t need super-duper sensitivity,” says Mina. “You just need to know if you are positive so you know that treatment is right for you and that you’re infectious and should probably stay home.
Why expanding self-testing is important
Increased access to self testing would likely give experts a better window into exactly how much disease was circulating in a given region. “[Health care professionals] are doing so little testing for flu and RSV at baseline now, it’s not like we would be facing a loss of pre-existing surveillance if more people test at home,” says Langelier.
“I almost guarantee that five years from now, everyone will have access to these,” says Mina of self-tests for common infectious illnesses. “We are in the ugly duckling phase where the antigen self-tests are not perfect, but we can combine them with telehealth technology to better enhance people’s ability to care for themselves. We have to start somewhere, and it’s going to get better.”
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Contributor: Alice Park