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What COVID-19 test is best for you? The truth about rapid, PCR, antigen, and antibody tests

January 11, 2022, 4:55 PM UTC

The rapid spread and high infection rate of the Omicron variant have prompted a run on COVID-19 tests at doctor’s offices, pharmacies, and other businesses that carry at-home tests. Making matters even more complicated is conflicting guidance on the accuracy of some of those tests when it comes to the variant.

In late December, the Food and Drug Administration announced rapid antigen tests may now have “reduced sensitivity” in detecting Omicron. Then, earlier this month, a study from a group of U.S. researchers indicated Omicron was better detected with a saliva swab than a nasal one. (The study was not peer-reviewed.)

The conflicting messages, along with shifting CDC guidance on quarantine periods, has only made it more confusing for people to navigate this stage of the pandemic.

Concerned you might have been exposed to COVID and not sure what to do next? Here’s what the experts are saying.

What are the different types of COVID-19 tests?

Ultimately, there are only two types of tests for active COVID and its variants—antigen and molecular. But each of these encompasses a variety of offerings. A third sort of test, which measures antibodies, looks for past signs of the virus.

Molecular COVID testing

These tests, best known as PCR tests, are the most accurate, but take longer to get results, sometimes up to five days or more. It can be done two ways:

Nasal swab: You’re probably familiar with this one. A giant Q-tip goes up your nose and is swirled around for a bit, then sent to the lab for testing.

Saliva: PCR saliva tests don’t involve a swab. Instead, you’ll spit into a funnel attached to a tube several times, then screw a cap on the tube to complete the test. It’s not a quick test. The Minnesota Department of Health notes it generally takes 10 to 12 minutes to gather enough spit to fill the tube, making this less than ideal for young children and some other groups.

Antigen COVID testing

Rapid tests are the most common test on the market these days—and use nasal swabs. They are less accurate than PCR tests, but can be done nearly anywhere. They’re generally administered by one of two methods:

At-home tests: Assuming you can find one, these (typically starting at about $20) let you test yourself in the comfort of your own home, reducing the possible exposure to other people. The downside is not everyone uses them correctly.

Rapid test at pharmacy/doctor’s office: It’s largely the same test as the at-home, but administered by a medical professional who’s more likely to perform the nasal swab as intended.

“I think it’s a good assumption that home tests are not as accurate as [PCR] tests you can get at a drive-thru or walk-in testing site, but they do improve access to testing,” says Yale’s Dr. Richard Martinello.

Antibody tests

Also called serology tests, these use blood draws to tell if you’ve had COVID-19 in the past, but do not identify if someone has COVID at the moment.

How accurate are at-home tests?

At-home tests aren’t perfect, but a lot of the issues come down to user error. For instance, if you’re told to do a nasal swab, you need to do a thorough swab, tracing the inside of your nose, not just quickly sticking it in, a common error with many users.

Experts, though, say you should trust the results if you test positive and isolate for at least five days. At the end of that period, take another test. If you test positive again, quarantine for another five days.

At-home tests, or rapid antigen tests, have a lower sensitivity than PCR tests for all variants (roughly 80% to 90% compared with a PCR), so they will give false negatives more often. Omicron throws a wrench into the works, since they’re less effective at picking up that variant, bringing the false negative count even higher.

Should I have a throat swab instead of a nasal swab?

There’s some evidence that Omicron multiplies more in the throat than the lungs, which might be part of the reason it has thus far proved less fatal. That, along with recent social media posts about it online, has led to a surge in interest in throat swab tests.

The hiccup is: All of the at-home tests that have been approved for use in the U.S. so far use nasal swabs, not throat swabs. To get a saliva-based examination, you’ll need a PCR test, which won’t give you results instantaneously (and doesn’t use a swab, but rather collects saliva).

Can I use a throat swab with my at-home COVID test?

Some people, including epidemiologists, are suggesting people consider adding a throat swab (done by using a nasal swab on your throat) to the nasal swab, saying it increases the tests’ accuracy, particularly when it comes to the Omicron variant.

The FDA and CDC, though, say that’s not a good idea, and urge people to use the tests only as they’ve been authorized, telling the Washington Post a self-administered throat swab could result in harm to patients. Other epidemiologists the Post spoke with warned the practice could result in more false positives with rapid tests, as they weren’t designed to test throat swabs.

What type of test should I get?

That depends on what you need it for.

Travel: A PCR test is what experts at Yale recommend before you go on a trip—and some countries require a PCR versus an antigen test to enter their borders.

School/workplace: Antigen tests are generally considered satisfactory, since the risk of exposure occurs daily.

Worried about possible exposure: Looking for some answers on whether you’ve got the sniffles or a mild case of COVID? An at-home or antigen test is generally the best bet, given its lower expense and wider availability. Just remember to wait three to five days after you fear you were around someone with the virus to test yourself.

The pharmacy is sold out. Should I buy an at-home COVID test online?

You can, but health officials warn that there are a growing number of scams preying on people who are desperate to find an at-home test. Know which tests are FDA approved and stick with that list. The most common names are Abbott’s BinaxNow and iHealth Labs’ test (sold on Amazon).

If you’re having trouble finding an at-home test, there are tools that can help you locate one

Will the test tell me if I have the Omicron variant, Delta variant, or some other form of COVID?

It won’t. The tests aren’t designed to break out whether you’ve got a variant or the original form of the coronavirus. That requires genetic testing, which is done in labs—and only a fraction of the total samples are sent to the lab, where they are anonymously sequenced. The breakdown of those tests forms the estimate for the total cases in your area.

Will my insurance pay for an at-home COVID test?

As of Jan. 15, yes. The Biden administration, on Monday, announced insurance companies and health plans would be required to cover up to eight at-home tests per month per person, paying as much as $12 per test.

“We are requiring insurers and group health plans to make tests free for millions of Americans. This is all part of our overall strategy to ramp up access to easy-to-use, at-home tests at no cost,” said HHS Secretary Xavier Becerra.

Will Medicare pay for an at-home COVID test?

State Medicaid programs and Children’s Health Insurance Program (CHIP) plans are currently required to cover FDA-authorized at-home COVID-19 tests without cost sharing. Medicare also pays for diagnostic tests performed by a laboratory, such as PCR and antigen tests, with no beneficiary cost sharing when the test is ordered by a physician, nonphysician practitioner, pharmacist, or other authorized health care professional.

Can I test positive for COVID even after I’ve recovered?

It’s possible. PCR tests search for even the smallest trace of COVID-19 and are so precise that they can identify the virus in your system long after you’ve recovered and aren’t contagious, which can alarm people who take them. As a result, PCR tests aren’t the optimal choice to find out when you should end isolation. An antigen test will confirm when it’s safe.

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