When and How You Can Test Yourself for COVID-19 At Home

When history looks back on the COVID-19 pandemic, 2020 will likely emerge as the year of testing, while 2021 (and likely 2022) will be the year of vaccinations. But that doesn’t mean testing no longer matters.

In fact, testing will become more critical than ever as schools, gyms, workplaces, restaurants and shops reopen, and sports events and concerts rev up again. Given that reality, the recent availability of at-home, DIY tests is welcome news. As of last week, Abbott’s BinaxNOW COVID-19 test—which doctors and hospitals have already been using to screen people—started to become available at retail stores without a prescription.

That’s just in time for the exodus from lockdown and social isolation expected this summer. As people start mingling again, they will need access to more convenient, rapid testing that can provide immediate answers—did my child get infected after playing in the soccer game? Is it safe to have a family dinner with relatives who don’t live with you? Did I get infected after going back to work?

The gold standard testing for SARS-CoV-2, called molecular, or PCR, testing, requires people to go to a health care professional, who swabs a sample from deep in the back of the nose and throat, and then sends the sample to a lab that performs the test. Results take at least a day. But such testing isn’t always necessary. In the coming months, being able to test yourself not once, but as often as you need to, to ensure you haven’t been infected from your activities, will become the priority.

The reason for that has to do with the changing landscape of the pandemic. Last year, when infections were spreading like a fire blazing out of control, testing was essential for identifying people who were positive so they could isolate and get the proper care. In most cases, doctors focused testing on people who had symptoms of COVID-19 like coughs, fever, chills and difficulty breathing. If you weren’t feeling sick, there wasn’t a reason to get tested, especially at the beginning of the pandemic when the tests were scarce and took a week or more to produce results,

As more people get vaccinated, however, theoretically, fewer people will be infected and even fewer will have symptoms. Instead of an inferno, the infections will be more like embers, scattered in communities here and there, and harder to find.

That’s where home, or DIY testing like Abbott’s kit, come in. These are tests that people can buy at their local pharmacy without a prescription, perform on their own without any medical help, and get results in about 15 minutes.

The U.S. Food and Drug Administration (FDA) has now authorized four such at-home over-the-counter COVID-19 tests: two from Abbott (the BinaxNow, as well as the BinaxNow Ag Card, which allows people to collect the sample and perform the test while connected to a telehealth provider (an option for those who want the guidance of a professional), and one each from Quidel and Ellume. People swab their noses—not the back of the nose and throat that the other test requires—and place the sample in a specially treated card or tube that provides results, similar to the results of a pregnancy test, in 15 minutes. They are all antigen-based tests, which means that they pick up proteins made by the SARS-CoV-2 virus, and not the virus itself. But the level of viral proteins is a proxy for how active, and therefore infectious, the virus is. SARS-CoV-2 is busiest in the first week or so after infecting a new host, pumping out more and more copies of itself. That’s when people are most at danger of passing the virus on to others, through coughs, sneezes or other close contact, even if they don’t feel any symptoms. And those are the exact people these antigen tests are designed to find.

How at-home antigen tests can slow the pandemic

“These tests aren’t just to tell you if you are sick,” says Dr. Michael Mina, assistant professor of epidemiology at Harvard T. H. Chan School of Public Health. “These tests are society’s way of being able to see the enemy around us, and in this case the enemy happens to be a virus. If you can’t see it, then you don’t know what precautions to take.”

Because they don’t require a prescription, and anyone can take the tests, Mina says their availability should vastly increase access to testing which should in turn help limit the spread of the virus. Parents worried about whether their child’s cough and fever is due to a cold or COVID-19 can use the test at home, for example, and if it’s positive, get in touch with a pediatrician—all without having to bring their sick child into the doctor’s office and potentially infect more people.

People attending small gatherings, or taking a trip, can test themselves beforehand and afterward, so they can be reassured that they haven’t been infected. And schools can rely on the tests to screen for and isolate any positive students or staff, and trace any potentially exposed contacts as quickly as possible.

Ideally, such democratized testing should have been the foundation for the COVID-19 response from the start, says Mina. Instead, since the first test for SARS-CoV-2, from the U.S. Centers for Disease Control (CDC), was slow to roll out after problems arose with its accuracy, and regulatory agencies like the FDA were initially hesitant to allow commercial and academic tests on the market, health officials have been blindfolded in trying to fight the virus. “In lieu of testing extensively, the whole pandemic, we treated everyone like they were positive,” says Mina, “and we had to shut the whole of society down because we’ve been blind.”

The at-home tests could finally give us the eyes that we’ve needed into the virus’ comings and goings—and help to avoid another blanket shutdown. In Maryland, the health department is piloting programs to use at-home rapid testing to identify cases among high-risk populations such as home care health workers and people with disabilities. “We’re trying to target folks who can’t afford to get tested but can benefit from having them,” says Jonathan Weinstein, director of COVID-19 testing passports for the department. Weinstein also sees the self-tests as a way to expand the reach of testing by making them available at places like schools, festivals and baseball stadiums.

How public health officials can make at-home testing even more useful

One barrier to widespread use of the self tests, however, is concern about their accuracy, since health professionals won’t be involved in collecting the samples or interpreting the results. That’s the reason that some experts don’t see them as powerful public health tools, although they might be useful for individual people making personal decisions. “There are lots of conundrums for public health that we are trying to work through,” says Kris Ehresmann, director of infectious disease epidemiology, prevention and control at the Minnesota department of health. “I don’t want to suggest that they have no utility. Just that from a public health system and data collection perspective, and how we do our broader recommendations, I think there are enough gaps in validation and quality of the results that we have to really be careful.”

She notes that self-tests are a good starting point to identify possible new cases, but that using them to take broader action is still problematic. If, for example, a student on a school soccer team tests positive using an at-home self-test, is that enough to quarantine the rest of the team, who might have been exposed to that player, and pull the entire team from upcoming games? To make those kinds of decisions, she says, “You want to make sure you are feeling really confident about the sensitivity and specificity of the test. I think there will be a lot of learning in the next months and years until we ultimately get to a place where we can speak more confidently about the role and place these tests will have.”

Those decisions will also depend on the balance between the test’s sensitivity in detecting infections, and its convenience and accessibility. A CDC study of Abbott’s tests (both use the same chemistry) conducted at community health centers in November and December of 2020, and compared it to the results of PCR tests. They found that the Abbott test picked up 64% of cases among people with symptoms, but only 35% among those who did not. Because symptoms usually occur within days of infection, however, Abbott says its test is useful for identifying people who are most infectious, and therefore could be helpful in identifying infected people early and ultimately controlling spread of disease.

Mina points out that the use case for at-home testing is different than that of molecular, or PCR testing. At-home testing, he says, is better suited to screening a population for infections, where the more involved PCR test isn’t always necessary or practical. And for much of the beginning of the pandemic, the FDA only allowed PCR testing even if it meant people waited as long as 10 days for the results. That strategy slowed the availability of at home testing in the U.S.; they are only now becoming widely available just over a year after the first case was confirmed, when they could have been useful all along in giving public health officials a better sense of where cases were before they became clusters. “We want everything to be totally controlled and totally perfect even if it is at the expense of testing failing,” he says. “We would rather not have any test than an imperfect test, which doesn’t make sense.”

The goal of testing is also changing, from one that is entirely focused on public health needs to one that is increasingly personal and individual. “If you are asking if you can go see grandma right now, you’re asking if you are infectious right now. And that’s what the quick at-home tests allow,” says Mina. “What the super-high-sensitivity PCR tests are doing is effectively finding if someone was infectious two or three weeks ago, and that’s not the information you really want about whether it’s safe to visit your grandma right now.”

“Public health is all about dealing with messy data,” he adds, about the potential that some results may not be as accurate as PCR testing. “We can look for signals in the noise.” One way to do that is to repeat the antigen at-home tests to have more confidence in the result. Indeed, Abbott’s BinaxNOW kit comes with two tests so users can do just that. Mina does acknowledge, however, that the at-home tests could become more useful for public health purposes if they include a way for people to easily report the results to their local health authorities so the data can be collected in a more systematic way. “We should be linking the tests to simple one-click reporting that should be anonymous and only geolocates by your zip code,” he says. “If we have more testing, then even if a small fraction of people are reporting, then ultimately that would provide more public health data, not less. Not having that reporting option is a big mistake.”

Given that the FDA appears to be leaning toward encouraging at-home testing, that could become a huge missed opportunity. The agency has also authorized two at-home, over-the-counter PCR tests, from Lucira and Cue, which are more than 90% accurate in replicating results from lab-based PCR tests—and ready in 20- to 30 minutes, rather than a day or so. Eventually, people may use the cheaper antigen tests, which run $20 to $30, on a more regular basis, and if they test positive, spring for the $50-plus at-home PCR tests to confirm the result.

As more people take advantage of self-testing, it’s now up to the CDC to take advantage of new funding for COVID-19 surveillance to find ways to tap into and exploit that data as more people engage in social activities and want to reassure themselves that they’re doing so safely. Mina says most of the tests are still not cheap enough to truly reach everyone who would want to use them—but it’s a start. “Self tests are a really, really powerful tool at your disposal if and when we need it,” he says.