How Accurate Are At-Home COVID Tests?

Testing for COVID-19 got off to a slow start at the beginning of the coronavirus pandemic. The disease spread quickly, in part because many people didn’t know they were contagious.

Now, COVID tests are readily available. It only takes a few minutes to find out if you have COVID and if you could spread the virus. And most people can complete a test without leaving home. This makes a big difference in keeping the virus from spreading through communities.

But how accurate are home COVID tests? And which one will give you the best results? Here, we’ll answer some common questions about at-home COVID tests, including how they work, who should use them, and when.

How do at-home COVID-19 tests work?

For the most part, at-home COVID tests are rapid antigen (Ag or RAT) tests. Rapid antigen tests use microscopic tags that recognize viral particles, or antigens, in the mucus from your nose. When you use the test correctly, viral antigens the swab picks up cause a color change in an indicator area on a test strip or card.

Rapid antigen tests are useful because they work quickly and don’t require much equipment. Typically, results take 10 to 15 minutes. 

The downside of antigen testing is that these tests aren’t very sensitive. That means that even if the test is negative, you could still have the virus that causes COVID. There needs to be a pretty heavy load of virus in your nose for the test to turn positive. If only a small amount of virus is present, the test may not pick it up and you could get a negative result.

Keep in mind that at-home COVID tests look for signs of the virus itself. The test is only looking to see if you currently have the virus. It can’t detect antibodies or other signs of immunity in your body.  

How do you take a home COVID test?

At-home COVID test kits contain all the materials and instructions you need to test yourself for COVID. The kits are available over the counter (OTC) in many pharmacies and online. Each test can be used only once. Each kit is a little different, but they all share the same basic steps. You should follow the instructions that are specific to your kit. 

In general though, here are the steps for a home COVID test:

• Wash your hands with soap and water.

• Use a swab to collect material from inside your nose. This is done by inserting the swab about a half inch into your nostril and twirling it around.

• Take the swab out of your nostril and mix it into a vial of chemicals.

• Using a dropper, pour a few drops of the chemical solution onto a test strip.

• Set a timer for 10 to 15 minutes.

• When the timer goes off, check the test strip for your results.

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When checking your results, there should always be a marking next to the letter “C.” This marking is the “control,” and it changes color to let you know that you performed the test correctly. It doesn’t mean you have COVID. 

If there’s a marking next to the letter “T,” this marking is for “test results.” If you see a marking or color change, it may mean that you’ve tested positive for COVID. 

How accurate are at-home COVID-19 tests?

At-home COVID antigen tests are pretty good at detecting the virus that causes COVID while you’re experiencing symptoms. They’re not as good at detecting low levels of the virus. A low virus level can happen during the first few days of an infection or after you start to feel better. So, a positive result on an at-home antigen test is a strong sign that you have COVID. 

But a negative result needs careful consideration. You might have a negative antigen test but actually have a COVID infection. This can happen in the following cases:

• You tested too early (fewer than 5 days after an exposure).

• You have a very mild case, or you’re starting to get better.

• You didn’t get a very good swab from inside your nose.

• You didn’t use the test correctly, or the test was damaged or expired.

• You have a variant of the virus that the test doesn’t detect very well.

If you think you have COVID but your at-home COVID antigen test is negative, repeat the test in 48 hours. In the meantime, take steps to avoid possibly spreading it and talk with a healthcare professional. Other, more accurate ways of testing for COVID are available in a medical setting. 

Are expired home COVID tests still accurate?

The test strips used in home COVID tests contain proteins that react and change color if your COVID test is positive. These proteins can break down over time though. If your COVID test is expired, it’s possible that you can get a false negative result.

Many home COVID tests have an extended expiration date. This means that these tests work just fine even after the expiration date printed on their package. To check if your home COVID test has an extended expiration date, check out this database from the FDA.

How accurate is a PCR COVID-19 test?

The most accurate COVID test is a PCR test. This is sometimes called a molecular test, or a nucleic acid amplification test (NAAT test).

These tests are usually sent to a laboratory and take a couple of days to come back. Typically, you get PCR tests from a healthcare professional. But there are some at-home PCR tests too. 

PCR tests can detect the virus even at very low levels. This makes a PCR test more sensitive than antigen testing. And so, if the result comes back negative, you can be more confident that you’re not infected.

There are now at-home COVID test kits designed to bring PCR-like technology into the home. These tests are more expensive than other types of test kits, but they can be useful. They combine the accuracy of PCR testing with the convenience of an at-home antigen test.

When should you use an at-home COVID-19 test?

Test yourself for COVID right away if you have symptoms, such as:

• Fever or chills

• Cough

• Shortness of breath or difficulty breathing

• Fatigue

• Muscle or body aches

• Headache

• New loss of taste or smell

• Sore throat

• Congestion or runny nose

• Nausea or vomiting

• Diarrhea

You should also test if you think you were exposed to COVID, even if you don’t have symptoms. But you’ll want to wait 5 days before you test.

Where to buy at-home COVID tests?

Free at-home COVID tests are available from the U.S. government as long as they’re being distributed. You can also find at-home tests for purchase in your community. 

Here are some places to try:

• Pharmacies

• Retail stores

• Online

To make sure you’re getting the best test for you, check out the list of FDA-approved at-home COVID tests before buying one.

If you’re looking for low- or no-cost testing options, here are some choices:

• Contact your local health department.

• Look for community-based testing sites near you.

• Search the CDC’s no-cost testing database by ZIP code.

Does insurance cover at-home coronavirus testing?

Medicare and most private health insurance will typically cover testing by a healthcare professional. But they may not cover at-home testing. Medicaid coverage will vary by state. Check with your insurance provider to figure out what type of testing is covered under your plan. 

Can you use an at-home COVID test if you recently had COVID?

Your at-home COVID test might show up as positive if you recently had COVID. That’s because viral particles can continue to circulate in your body after you’ve recovered. Very sensitive tests, such as PCR tests, can continue to show a positive result for up to 90 days after a COVID infection. Antigen tests can continue to show a positive result for up to 30 days. 

If you recover from COVID and your symptoms come back within 90 days, don’t use a PCR test to see if you’re contagious again. Instead, choose an antigen test. If the result is negative, repeat it 48 hours later so you can trust the result.

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Written by:

Kerry R. McGee, MD, FAAP

Kerry McGee, MD, FAAP, has over a decade of experience caring for babies, children, and teenagers as a primary care pediatrician. She has a special interest in adolescent health, particularly in adolescent mental health.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

Reviewed by:

Farzon A. Nahvi, MD

Dr. Nahvi is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works clinically at Concord Hospital in Concord, New Hampshire, and is a clinical assistant professor of emergency medicine at the Geisel School of Medicine at Dartmouth. Prior to this, he worked as an ER physician and clinical assistant professor of emergency medicine at the Mount Sinai Health System, NYU Langone Health, NYC Health + Hospitals/Bellevue, and the Manhattan VA. He is a graduate of Cornell University and NYU School of Medicine.

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