What you need to know about at-home COVID testing
The guidance that comes in the test kits is so confusing that a study published in JAMA showed that it was worse than no enclosed advice at all. Credit: AP/Tom Williams
The overwhelming majority of COVID-19 tests are now done at home, a leading expert estimates. Knowing when and how to use them is key. Here are answers to some commonly asked questions.
How accurate are at-home rapid tests?
They’re significantly less accurate than PCR tests, said Dr. Luis Marcos, an associate professor in the Renaissance School of Medicine at Stony Brook University and an infectious disease expert.
You’re most likely to get an accurate result on either test about one to three days after symptoms begin, and even then, rapid tests only detect the virus in about 60% of cases, he said. That compares with about 80% for PCRs.
If you do not have symptoms, test at least five days after possible exposure, according to the Centers for Disease Control and Prevention.
If a rapid test is less accurate, why take it rather than a PCR?
It often takes two to three days to get the results of a PCR test, Marcos said. During that time, “You may not be in isolation, you may think you are not positive, and the spread will continue,” he said. “At least with a rapid test you have something quick. You can diagnose people faster, isolate them faster and stop the spread.”
If going to an indoor gathering — especially if there are people there at higher risk for severe COVID-19 — take the rapid test as close to the time of the event as possible, the CDC says.
Dr. Luis Marcos, an associate professor in the Renaissance School of Medicine at Stony Brook University. Credit: James Carbone
If the rapid test often doesn’t detect the virus, does that mean I can test negative and still be contagious?
Yes. If you test negative but have COVID-19 symptoms, believe you were near people with COVID-19, were unmasked in a large crowd or were in other risky situations, “You might want to isolate and follow up with a PCR test” or additional rapid tests later, said Stephanie Silvera, an epidemiologist and professor of public health at Montclair State University in New Jersey.
If you test negative, you may be less likely to transmit the virus, because a negative test may mean you have a lower amount of virus in your body, Marcos said.
Silvera recommends using rapid tests to determine when to come out of isolation after a positive test or after having symptoms. If you test positive, “That means you still have a high viral load, in which case you really shouldn’t be going back out and gathering with people,” Silvera said.
Stephanie Silvera, an epidemiologist and professor of public health at Montclair State University in New Jersey. Credit: Corey Sipkin
Why does the rapid test often not detect the virus?
It takes a few days for the virus to multiply in the body to reach a high enough level for an at-home test to detect it, Marcos said. So if you were just infected with the virus, it won’t show up on a rapid test, or even a PCR, he said.
“There are not a lot of false positives,” so if the test says you’re positive, you’re almost surely positive, Silvera said.
What is it about a rapid test that makes it less accurate than a PCR?
The rapid test detects the protein of the virus, which is like "a big arm of the virus," Marcos said. The PCR is more sensitive and "will detect the RNA, or the genetic material, which is much smaller than the protein,” and it will amplify that genetic material, he said. The rapid test is not sensitive enough to detect the genetic material.
There are detailed instructions for how to perform at-home tests. Do I really have to follow them?
Yes, “The instructions have to be followed exactly” to reduce the chance of a false negative, Marcos said.
Is there a way to get free tests?
Yes. Every U.S. household can obtain two kits that each contain four tests. Go to https://www.covid.gov/tests. In addition, New York State has distributed more than 70 million home test kits.
Does my insurance cover the tests?
The Biden administration in January began requiring insurance companies to cover the cost of at-home tests, up to eight tests per individual per month. Insurance payments may be upfront or by submitting a claim. Contact your insurance company for details. There are limits on out-of-network coverage. Medicaid fully covers the cost of tests. Medicare coverage depends on the type of Medicare Advantage plan.
A recent CDC study found that Black, Latino and Asian people were less likely to use home tests than white people, and that at-home test use rose as income rose. Why is that so?
Cost is a big factor, Silvera said. Most people are unaware they can get free tests, and filling out insurance paperwork can be complicated, she said.
“You have to pay an average of $10 to $25 for these tests,” she said. “If you have multiple people in your home or you feel like you’ll need the test more than once, that can get quite expensive.”
More outreach on how to obtain free tests is needed, she said.
How common are at-home tests?
Mara Aspinall, a professor of practice in the Arizona State University College of Health Solutions and a COVID-19 adviser to the Rockefeller Foundation, said Thursday that, in recent weeks, there typically were roughly 30 million to 35 million rapid tests performed every week, down by about half from the January omicron surge. All but a small percentage of those rapid tests were done at home. The numbers are based on data from manufacturers, retailers and individual sampling, so they are general estimates, Aspinall said.
In contrast, there are currently about 5 million to 6 million lab-based PCR tests performed a week.
David Olson covers health care. He has worked at Newsday since 2015 and previously covered immigration, multicultural issues and religion at The Press-Enterprise in Southern California.
