How Accurate Are Rapid COVID-19 Tests?

Since the start of the COVID-19 pandemic, testing for COVID has been one of the most important tools in our fight against the virus. Early on, it sometimes took days to weeks to get test results. But with fewer roadblocks and improvements in rapid testing, now you can get faster results.

Rapid COVID tests are available at healthcare offices and on the shelves of your local pharmacy or supermarket. Here, we’ll cover the basics of rapid COVID tests, how fast they are, and the accuracy of the results. 

What is a rapid COVID test, and how do they work?

The key difference between rapid tests and standard laboratory tests is how long they take to process results. As the name suggests, rapid tests can produce fast results. In general, most rapid tests provide results in 15 to 30 minutes.

You can do rapid tests at point of care, like a testing site or a medical clinic. They don’t need an outside lab to process. What’s more, many rapid tests are available over the counter (OTC). You can also buy these tests without an order or prescription from a healthcare professional. And you can get results with these tests from the comfort of your home.

Types of rapid COVID tests

There are two different types of rapid COVID tests available: molecular and antigen. These tests work differently in how they detect SARS-CoV-2, the virus that causes COVID.

Rapid molecular tests

Molecular tests are the most accurate type of COVID test available. Molecular tests detect the presence of viral genetic material in a sample. They were the first type of COVID test to be authorized and widely used. 

Many rapid molecular tests have been authorized for use in healthcare settings and for at-home use. These include several that can also test for other viruses, like those that cause the flu (influenza). Most of these tests provide results in 30 minutes or less. 

There are FDA-approved, at-home COVID test kits designed to bring PCR-like technology completely into the home: 

• 3EO Health COVID-19 Test

• Lucira Check-It COVID-19 Test

• Lucira COVID-19 & Flu Home Test

• Metrix COVID-19 Test by Aptitude 

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How much is a rapid molecular test?

Rapid molecular COVID tests are more expensive than other types of test kits, You can buy a rapid molecular test on Amazon for under $25. Your health insurance may cover the cost of rapid molecular tests. If you’re paying out of pocket, keep in mind that the cost can vary widely across the U.S.

Although they can be pricey, rapid molecular at-home COVID tests can be useful. These tests combine the accuracy of PCR testing with the convenience of an at-home antigen test. They deliver results in 30 to 60 minutes.

Rapid antigen tests

Antigen tests are the most widely available rapid COVID test. Antigen tests look for specific proteins on the surface of the virus. These tests tend to be simpler in design and less expensive than molecular tests. But they’re less accurate than molecular tests.

Many antigen tests have been authorized for use in clinic settings or at home. Several are available OTC, and tests typically take about 15 minutes to get results. 

How much is a rapid antigen test?

Your health insurance may cover the costs of these tests. If you have a flexible spending account (FSA), check the eligibility of rapid antigen COVID tests. The median self-pay price for a rapid antigen COVID test at a hospital or outpatient setting is $51. 

You can also buy them at many locations, including grocery stores and online. The cost ranges from less than $10 to over $25, depending on the brand.

How accurate are rapid COVID tests?

Now that you know a little more about how rapid COVID tests work, let’s go over the accuracy of the two types of tests. 

Accuracy of molecular tests

Molecular tests are the gold standard (most accurate option) for COVID testing. Rapid molecular COVID tests use the same technology as the tests in labs, and they can detect low levels of virus. If you have a positive result from a rapid molecular COVID test, you’re infected with the COVID virus. 

A negative rapid molecular COVID test means the test didn’t detect the COVID virus. If you have symptoms, you may still have COVID. But if you test too early, you may not have enough virus to cause a positive result. This is a “false-negative” result. That means you’re infected with the virus, but you’ve tested negative.

If you test negative, it’s also possible you have another infection that causes similar symptoms, like the flu. Either way, it’s important to monitor your symptoms, check in with a healthcare professional, and take basic prevention measures so you don’t spread the virus to anyone else.

Accuracy of antigen tests

Rapid antigen tests are more widely available than molecular tests. Although they’re less accurate, they’re still a good test to figure out if you have COVID or not. 

Test sensitivity

Rapid antigen tests don’t detect low levels of virus. So you may be more likely to get a false-negative result with a rapid antigen test. This is the sensitivity of a test. Because the sensitivity is less than 100%, there’s a chance that you may have COVID even if the test is negative. This is more likely if you test early in the disease, or after you start feeling better.

Test specificity

Researchers have found that most rapid antigen tests have very high specificity. That means the test has very few false-positive results. With a specificity of nearly or at 100%, if you get a positive result on a rapid antigen test, then you have a COVID infection. 

Comparing molecular vs. antigen test accuracy

The sensitivity and specificity of rapid COVID tests can vary widely. In general, rapid molecular COVID tests tend to have higher sensitivity and specificity than rapid antigen tests. 

Below is a table of some of the sensitivities and specificities of common rapid COVID tests.

What causes a false positive on a rapid COVID test?

Rapid COVID tests are very good at correctly identifying people who have a COVID infection. But you must follow the test instructions to get this high level of accuracy. There have been cases where people received a positive result on a rapid COVID test — but in fact they didn’t have COVID. These are typically due to user error.

For example, one study found that contaminating the test with commercial drinks like juice and soda can result in a false positive. You can imagine this might happen when testing school kids in a lunchroom. 

Another study found false-positive results due to a manufacturing error in a batch of tests.

What causes a false negative on a rapid COVID test?

There are two common causes of false negative results on a rapid COVID test: user error and low levels of the virus.

User error

Rapid COVID tests include several steps: 

• Swabbing your nose

• Mixing the swab with chemicals included in your kit

• Adding a few drops of the chemical mixture on a test strip

Along the way, a lot can go wrong. Some people might not swab their nose the right way. Or you might mix the chemicals incorrectly. A mistake in any one of these steps can cause a false negative result. 

Low virus levels

When you’re infected with COVID, the virus is circulating throughout your body. COVID likes to hang out in the nose. But it’s possible there’s not enough of the virus in your nose at the time of your test. This can happen because it’s early on in your illness. Or it could simply be because of normal variations in how the virus behaves. Low virus levels will make it harder to detect, and this can lead to a false negative result. 

How to increase the accuracy of a rapid test

Timing is essential when using rapid COVID tests. You’re more likely to have a false-negative result if you:

• Tested too early (fewer than 5 days after an exposure)

• Have a very mild case, or you’re starting to get better

• Didn’t get a good swab from inside your nose

• Didn’t use the test correctly, or the test was damaged or expired

• Have a variant of the virus that the test doesn’t detect very well

If you’re using at-home rapid antigen tests, it’s recommended that you test multiple times over the course of a few days. For example, if you’re experiencing symptoms but test negative, test again 48 hours later. 

If at any point you test positive, you likely have a COVID infection.

If you’ve been exposed to the virus and don’t have symptoms, wait at least 5 days to test. If you test negative, test again 24 to 48 hours later. 

Why do people still use rapid antigen COVID tests if they’re not as accurate?

Rapid antigen COVID tests are a quick, easy way to figure out if you have COVID, even if the results aren’t 100% accurate. 

The number-one thing to remember is that if your rapid antigen test is positive, you have a COVID infection. The chances of a false-positive result are very low. And it’s important to take any positive result seriously.

But you should interpret negative rapid antigen tests with caution and retest to be sure.

Where to find rapid testing near you

If you have COVID symptoms, or believe you’ve been exposed to the virus, you have several options for rapid tests. For example, pharmacies like CVS and Walgreens offer rapid antigen and molecular tests. 

You can also buy many OTC at-home tests online and at your local pharmacy and grocery store. You can do these tests yourself and get results in an hour or less, depending on the type of rapid test.

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Written by:

Angela Dunn, MD, MPH

Angela Dunn, MD, MPH, is a public health physician practicing in Utah, with a focus on serving under-resourced communities.

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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