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How to Use Rapid Home Tests (Once You Find Them)

As the Omicron variant spreads, regular home testing can lower risk, ease worry and allow you to live a more normal life.

Testing isn’t a substitute for being vaccinated or getting a booster shot. But at-home rapid tests can tell people within minutes whether they are contagious with Covid-19.Credit...Getty Images

The rapid spread of the Omicron variant has added even more uncertainty about how to navigate life after vaccination. Is it safe to gather unmasked with my vaccinated friends? Can I travel for the holidays? Can my children safely see their grandparents?

But rapid home testing can lower risk, ease worry and allow you to spend time with the people you care about.

Testing isn’t a substitute for being vaccinated or getting a booster shot. But at-home rapid tests can tell people within minutes whether they are contagious with Covid-19. It gives added assurance that no one at a child’s birthday party, a wedding or a family holiday gathering is spreading the virus. If you’ve been traveling through airports, it’s a good idea to take a few rapid tests, days apart, to make sure you didn’t contract the virus during your travels.

One big problem is that the tests can be hard to find. The Biden administration has promised an investment of $1 billion in home testing. Many stores and websites do still have tests in stock, but it may require some effort to find them. The administration has said that starting in December, an estimated 200 million rapid tests should be available to Americans each month.

No test is a 100 percent guarantee, but given that your vaccine and booster already protect you, a home test is another layer of precaution to lower risk. Unvaccinated people can benefit from using home tests as well, but they should not rely on testing as a substitute for a vaccine.

Home tests are particularly useful for families with young children who aren’t yet eligible for vaccination and for anyone with an at-risk family member. When my vaccinated daughter wanted to visit her 80-year-old vaccinated grandmother in New Mexico, she was tested in New York before leaving, and she carried several rapid home tests to use when she landed and every day of the short visit.

“Testing is an information business, and that information is liberating,” said Mara Aspinall, an expert in biomedical diagnostics at Arizona State University who is also on the board of OraSure, which makes rapid Covid tests. “For some, it’s going to be to not wear a mask at an event. For some, it’s going to be to go visit great grandma or interact with the public. If your test is positive, it means you’ve got the power to protect yourself and other people.”

In the United States, a boxed set of two tests can range from $14 to $24, making them too expensive for most people to use frequently. But home tests can still be a helpful way to lower the risk of indoor gatherings and spending time with extended family members.

“I think people should embrace home testing more,” said Neeraj Sood, a professor and vice dean for research at the University of Southern California and director of the Covid Initiative at the U.S.C. Schaeffer Center. “I’m planning to go to India. I’ll do the home test the moment I land to make sure I’m not infectious before I give a hug to my father.”

Most of the home tests on the market are rapid antigen tests. They work much like a pregnancy test with a pink line indicating you’re positive for the coronavirus. The tests all require you to swizzle a long swab in both nostrils. Depending on the test, you may insert the swab into a special card reader or dip the swab in a solution and use a test strip, then wait 10 to 15 minutes for the result.

Currently, there are several rapid home antigen tests available in the United States. The best known include Abbott’s BinaxNOW, Quidel’s QuickVue and the recently authorized test by Acon Labs, Flowflex. Newer tests on the market include the Intrivo On/Go, the iHealth Covid-19 test and the BD Veritor at-home digital test kit. The InteliSwab test has the longest wait time, at 30 to 40 minutes. Australia’s Ellume has been in the news for a high rate of false positives, but those faulty tests have been recalled. Most of the tests are typically packaged two per box, although Flowflex offers a single test pack for about $10. Read the label before you buy. Some of the tests require an app. Wired Magazine has a great summary of all the tests, how to use them and where to find them.

A more expensive test, called a rapid home molecular test, uses a technology similar to what you might get at the doctor’s office. But those tests can also be hard to find and are expensive, so they aren’t a practical option for most people to use regularly. The Lucira Check It test kit costs $75 and takes about 30 minutes. A new test, Detect, offers a $75 starter kit that includes a reusable “hub” that processes the test in about an hour. Additional Detect tests cost $49 each, but the tests are often sold out.

Although no test is 100 percent accurate, the new rapid home antigen tests are highly reliable for telling you whether you’re contagious on a given day. Testing studies have shown that rapid tests identify about 98 percent of cases in which a person is most infectious.

But it’s possible to test negative on one day and then test positive for Covid a few days later. That doesn’t mean the first rapid test was incorrect — it just means on the day you tested, you weren’t infectious yet, even though you later tested positive for the virus. (Rapid molecular tests and the test you get at the doctor’s office can also return a false negative, depending on the timing of the test.)

“If the test is negative and you later test positive, it’s not wrong,” said Gigi Gronvall, an associate professor at the Johns Hopkins Bloomberg School of Public Health. “The question the rapid antigen test is asking is, Do you have a lot of virus in your nose at this moment, yes or no?”

The timing of the test matters. Using one test is a useful precaution right before seeing friends or family members who want to gather indoors and unmasked. A quick test can also help a parent make sure a child’s cough or sniffle isn’t spreading Covid.

If you’re using a rapid test to lower the risk of a holiday gathering, make sure you take it on the same day of the event, preferably about 15 minutes before you walk in the door. Recently, a Christmas party in Norway became a superspreader event even though everyone was vaccinated and had used a rapid test. But in that case, people tested one day before the event.

Two tests are better than one. The biggest mistake people make using rapid home tests is taking a single test and thinking it means they don’t have Covid-19. If you’re worried that you’ve been exposed to Covid, you should take at least two tests over a three- to four-day period. The Centers for Disease Control and Prevention says the best testing window after a potential exposure is to test three to five days after the high-risk event or contact with an infected person.

The bottom line is that the more often you use the tests, the better, said Dr. Michael Mina, a former Harvard epidemiologist who is now the chief science officer for eMed, a company that verifies at-home test results. If you want to spend time with a medically vulnerable person, you should take a test a few days before seeing them, and then take another test on the day of the visit.

“Think about, How do I test as close as possible to the thing that I’m doing?” Dr. Mina said. “When I go visit my parents, I always bring rapid tests with me. Right before I walk in the door, I use the test in my car.”

Most of the time, a positive result means you have the coronavirus, particularly if you have symptoms. But false positives do happen. Recently, Ellume, an Australian company, recalled nearly 200,000 test kits because of concerns about a higher-than-expected rate of false positives.

If there’s reason to doubt a positive result, take another test, preferably from a different manufacturer or at a testing center. People hosting large events, like weddings, and using the tests to screen guests should have a few extra tests on hand from a different brand for those guests who test positive. You can be confident in the result if the second test is negative, Dr. Mina said.

“It would be really rare for someone to have a true positive and then have a second test show a false negative result,” he said. “If you’re having a dinner, you may as well just cancel dinner if someone tests positive. But if it’s a high-consequence event, like you’re having a wedding and flying somewhere, and you’re going to screen a few hundred people, you may get a false positive and want to test again.”

There’s no requirement to report the results of a home test to a public agency, but you should check in with your doctor. If you want to double check the result, you can get a confirmatory test at a testing center. On its website, the C.D.C. says that if you test positive using a home test, “you should isolate and inform your health care provider, as well as any close contacts.”

Because of high demand, the tests can be difficult to find right now. Try the websites of stores like CVS, Walgreens, Costco or Walmart, or check with a local drugstore. I recently searched the CVS website for a friend in New Jersey and found BinaxNOW tests at a store about 30 minutes away. When he arrived, he found the shelves stacked with tests.

A word of warning: Make sure you search by brand name. If a store is sold out of a rapid test, the website may direct you to a different type of test, called a home collection test, that requires you to mail the sample to get the result.

But hold out until you find a rapid test. “The fact that they are rapid,” Dr. Gronvall, of Johns Hopkins, said, is what “makes them a really great test to make sure somebody is not infectious at that moment.”


Tara Parker-Pope is a columnist covering health, behavior and relationships. She is the founding editor of Well, The Times's award-winning consumer health site. More about Tara Parker-Pope

A version of this article appears in print on  , Section D, Page 6 of the New York edition with the headline: At-Home Covid Tests Add a Layer of Precaution. Order Reprints | Today’s Paper | Subscribe

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