COVID-19 tests are a powerful tool for fighting the coronavirus, but misconceptions about them abound. Read on for the facts, plus testing tips.

With so many people getting COVID-19 vaccines and boosters, it’s easy to lose sight of the other important tools we have for taming the COVID-19 pandemic. Testing is an especially important measure that should not be overlooked.

Unfortunately, misconceptions about these tests are rampant, making it hard for people to separate truth from falsehoods.

Here, experts debunk some of the most common COVID-19 testing myths and tell how to use tests correctly.

Fact: The Centers for Disease Control and Prevention (CDC) recommends that testing occur in a wide range of situations. Of course, one of these occasions is when you have symptoms of COVID-19, which include fever or chills, headache, nausea, and loss of taste or smell, among other issues, whether or not you’ve been vaccinated.

But there are other times when testing is warranted, too. If you come in close contact with someone who has COVID-19, you should be tested immediately and again five to seven days later if you are unvaccinated, and five to seven days after exposure if you are fully vaccinated, the CDC advises.

Attending large gatherings and spending time in crowded indoor spaces are high-risk endeavors that will increase your risk of coming into close contact with someone who has COVID-19.

If you are unvaccinated and travel within the U.S., you should be tested three to five days afterwards, and you should stay home and self-quarantine for seven full days even if you test negative, the CDC advises. International air travel may also require testing, whether or not you are vaccinated, both before you leave home and prior to your return.

Moreover, “I would also recommend at least doing a rapid home test if you are planning to see someone who is immunosuppressed or elderly,” so you don’t inadvertently infect them, says Thersa Sweet, PhD, MPH, associate teaching professor of epidemiology and biostatistics at Drexel University in Philadelphia.

The CDC’s Viral Testing Tool provides additional guidance on when testing can be beneficial.

Fact: Testing is an important way for health experts to track how widespread the virus is in a community, says Gigi Kwik Gronvall, PhD, a senior scholar at Johns Hopkins Center for Health Security, who directs the Johns Hopkins Center’s COVID-19 Testing Toolkit.

“We know more about cases due to testing, but the testing doesn’t cause more cases,” Dr. Gronvall says.

Some people blame spikes in COVID-19 cases on an excessive amount of testing, but experts say that is not accurate. In fact, says Dr. Sweet, “If the percent positive is high, that actually means you’re not testing enough people.” She adds, “All of the spikes I have seen lately go hand in hand with an increase in the percent positivity, indicating that the spikes are true increases in the virus in a community.”

Fact: There are two different types of tests used to detect COVID-19. One is the polymerase chain reaction (PCR) tests, which looks for traces of the virus’s genetic material and is sensitive enough to detect infection in its earliest stage. These tests are available at dedicated COVID-19 testing sites, hospitals, doctor’s offices, and the like, with samples sent to a lab that typically provides results in one to several days.

The other main kind of diagnostic test is an antigen test, also known as a rapid test, which detects the presence of a specific molecule that implies a current viral infection but does not document it directly, making it a bit less accurate. Results are available within minutes, which is why this is the type of test used at home.

Especially for someone who is experiencing symptoms of COVID-19 or is at higher risk of infection, “The best test is the readily available test,” says Melanie Swift, MD, MPH, co-chair of Mayo Clinic’s COVID-19 Vaccine Allocation and Distribution Work Group in Rochester, Minnesota.

Because the antigen test can miss low levels of infection, if you get a negative result (meaning the test says you don’t have COVID-19), for maximum accuracy you need to take either a second antigen test — typically, from 24 to 48 hours later — or a PCR test to confirm, Dr. Swift says.

In many cases, the antigen test is the better option, she says. Because it can be used at home, “Antigen tests are a good choice for people without symptoms who want to be checked before or after traveling, or who need to be tested as part of a surveillance program,” Swift says.

Fact: At the beginning of the pandemic, COVID-19 tests required the insertion of a swab all the way back to where your nose meets the top of your throat, an area known as the nasopharynx. Scientists were sure if viral activity was present it would be found there, an area where the coronavirus replicates.

But many people can’t tolerate the feeling of a swab deep in the nasal passage, so testing criteria changed to the middle part of the nasal passage — less than an inch in — an area known as the mid-turbinate region. “This is much easier and more comfortable,” Sweet says.

Samples taken from the nasopharynx still remain the most accurate. A review study published in PLoS One in July 2021 found tests using a nasopharynx swab to be 98 percent accurate, while those using a mid-turbinate or even more shallow swabs range from 82 to 88 percent accurate.

Still, this lower sensitivity is offset by the ability to screen more patients, making it worth taking a shallower sample, the study authors conclude.

Fact: Several of the rapid COVID-19 test brands currently available, such as the Abbott BinaxNOW and the Quidel QuickVue, are packaged as a set of two.

If you get a negative result from one of these tests, you are instructed to take the second test within three days, letting some time pass between tests — generally at least 24 hours and no more than 48 hours (check the instructions in your kit to verify).

This is because antigen tests can give a false negative result if you test too early in the course of your disease, when your viral levels are too low to be detected. By the time you take the second test, it should be positive if you do have COVID-19.

(If either of the two tests is positive, you should reach out to your doctor and also stay home and isolate away from other people.)

Fact: When taking a home COVID-19 test, it is crucial that you follow the directions exactly as instructed. If you deviate even a little, your results may be inaccurate.

For example, with the Abbott BinaxNOW test, the instructions call for swabbing the inside of your nose for 15 seconds. If you swab for a shorter amount of time you may not pick up enough specimen for the test to find indications of the virus. Similarly, the test calls for exactly 6 drops of solution to be placed on the test card. More or fewer drops can make the test function improperly.

Because it is so important that you follow the test instructions exactly, you should always take a few minutes to read through all of the steps before you begin, even if you have done a test before.

Fact: Any of the authorized COVID-19 vaccines dramatically reduce the likelihood that you will catch COVID-19, and, especially, that you will be hospitalized or die from the disease.

Testing, by contrast, cannot keep you from getting sick. “Testing regularly won’t prevent COVID or stop the spread,” Gronvall says. This is similar to the way getting regular mammograms can’t keep you from getting breast cancer.

What regular testing can do is alert you early in the course of your disease that you are sick. You can then isolate so you don’t spread the disease to others, and also notify your close contacts that they should test and quarantine, too. In this way, you won’t spread COVID-19 to (many) others.

Still, there is no better way to protect yourself and others than to be vaccinated.

Fact: "A negative test is not a license to forego masking, social distancing, or other routine precautions when COVID is circulating in your community,” Swift says.

For one thing, Sweet says, “The tests are not foolproof. There are some false negatives,” where the test results would indicate that you were disease-free even though you were infected. Plus, a negative test means no virus was detected at the time of the test. It might be too early in your infection for the test to detect disease, or you might have been healthy when you took the test but then contracted COVID-19 after.

This means the best way to protect yourself and others is to mask and social distance when the virus is circulating, regularly wash your hands and, of course, get the vaccine and all boosters — in addition to testing when appropriate.

“It’s not an either-or. We really need a multi-tiered approach,” Sweet says.

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