What you need to know about home COVID testing

The overwhelming majority of COVID-19 tests are now done at home, a leading expert believes. Knowing when and how to use them is essential. Here are the answers to some frequently asked questions.

How accurate are rapid home tests?

They are significantly less accurate than PCR tests, said Dr. Luis Marcos, an associate professor at Stony Brook University’s Renaissance School of Medicine and an infectious disease expert.

You’re most likely to get an accurate result on either test around one to three days after symptoms start, and even then the rapid tests only pick up the virus in around 60% cases, he said. This compares to around 80% for PCRs.

If you don’t 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 results from a PCR test, Marcos said. During this time “you may not be isolated, you may think you are not positive and the spread will continue,” he said. “At least with a quick test you have something quick. You can diagnose people faster, isolate them faster, and stop the spread. »

If you’re going to an indoor gathering — especially if there are people at higher risk for severe COVID-19 — do the rapid test as close to the time of the event as possible, the CDC says.

Dr. Luis Marcos, associate professor at the Renaissance School of Medicine at Stony Brook University.
Credit: James Carbone

If the rapid test often does not detect the virus, does that mean I can test negative and still be contagious?

Yes. If you test negative but have symptoms of COVID-19, suspect you were around people with COVID-19, were unmasked in a large crowd, or were in other risky situations , “You may want to self-isolate and follow up with a PCR test” or other 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’re less likely to transmit the virus because a negative test can 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 testing positive or having symptoms. If you test positive, “that means you still have a high viral load, in which case you really shouldn’t go out and get together with people,” Silvera said.

Stephanie Silvera, epidemiologist and professor of public health at...

Stephanie Silvera, epidemiologist and professor of public health at Montclair State University in New Jersey.
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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 a home test to detect it, Marcos said. So if you’ve just been infected with the virus, it won’t show up on a rapid test, or even on a PCR, he said.

“There aren’t a lot of false positives,” so if the test says you’re positive, you’re almost certainly positive, Silvera said.

What’s in a rapid test that makes it less accurate than a PCR?

The rapid test picks up the virus protein, which is like “a big arm of the virus,” Marcos said. PCR is more sensitive and “will detect RNA, or genetic material, which is much smaller than protein,” and it will amplify that genetic material, he said. The rapid test is not sensitive enough to detect genetic material.

There are detailed instructions on how to perform home tests. Do I really have to follow them?

Yes, “instructions should be followed exactly” to reduce the risk of a false negative, Marcos said.

Is there a way to get free tests?

Yes. Each U.S. household can get two kits each containing four tests. Go to https://www.covid.gov/tests. Additionally, New York State has distributed more than 70 million home testing kits.

Does my insurance cover the tests?

The Biden administration began in January requiring insurance companies to cover the cost of home testing, up to eight tests per individual per month. Insurance payments can be upfront or by submitting a claim. Contact your insurance company for details. There are limits to off-grid coverage. Medicaid fully covers the cost of testing. Medicare coverage depends on the type of Medicare Advantage plan.

A recent CDC study found that blacks, Latinos, and Asians were less likely to use home testing than whites, and that use of home testing increased as income rose. Why is it so?

Cost is a big factor, Silvera said. Most people don’t know 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 think you need the test more than once, it can be quite expensive.”

More awareness about how to get free tests is needed, she said.

How often are home tests?

Mara Aspinall, professor of practice at Arizona State University College of Health Solutions and COVID-19 advisor to the Rockefeller Foundation, said Thursday that in recent weeks there have typically been about 30 to 35 million rapid tests performed. each week, down about half from January’s omicron surge. All but a small percentage of these rapid tests were done at home. The numbers are based on data from manufacturers, retailers and individual samples, so they’re general estimates, Aspinall said.

In contrast, there are currently around 5-6 million laboratory PCR tests performed per week.

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