Since the start of the coronavirus pandemic, testing has become vital, with a push centered around increasing testing and testing accessibility nationwide. According to The COVID Tracking Project, the number of people tested for COVID-19 has exceeded 1 million per day over the past month.

There are three main types of tests for the coronavirus: genetic test, antibody test, and antigen test. Although the most accurate tests, according to the CDC, are genetic or polymerase chain reaction (PCR) tests, antigen tests currently have high demand because results can be received significantly faster.

What is a rapid test?

These rapid tests, also known as point-of-care diagnostic tests, are antigen tests. They don’t require lab equipment and can be performed anywhere, including at home. The quick results theoretically let people know whether or not to isolate to avoid transmitting the disease.

“The molecular tests are looking at the virus’s RNA,” explained Mara Aspinall, professor of practice biomedical diagnostics at Arizona State University. “The antigen tests are essentially looking at the proteins on the surface of the cell and what the virus is shedding. The virus always sheds these antigens and the tests are looking at the material that is shed to say there must be the virus inside the cell.”

The FDA issued the first rapid antigen tests in May 2020. They require either a nasal or throat swab to analyze if there is an active infection, with results in as little as 15 minutes.

How accurate are rapid tests?

Rapid antigen tests are cheaper and can get results in a matter of minutes, but they are more likely to produce false negatives.

Experts explain that that’s due to its decreased sensitivity. A test’s sensitivity refers to how effectively the test can identify those with the virus. (Doctors also talk about “specificity.” That refers to how effectively the test can identify those without the virus.) According to the CDC, the first antigen tests that received FDA emergency use authorization showed sensitivity ranging from 84% to 97% (and specificity of 100%). So a negative result still leaves room for doubt.

That’s why, following a negative result from a rapid test, a molecular test if often still recommended by health care providers before taking next steps.

“What everyone wants is for a test to be cheap, accurate, and fast,” said Geoffrey Baird, PhD, a laboratory medicine specialist at the University of Washington, Seattle. “You can only ever have two of those.”

Rapid tests are often used for businesses, hotels, airports, and those returning to work or school as a way to quickly identify those who have the virus before they enter these public settings. But regardless, the “gold standard” of the CDC is the PCR test.

Where to get a rapid test?

Those who are experiencing COVID symptoms or have come in close contact with someone who has tested positive for the virus should get a test. As of now, there are six antigen tests authorized by the FDA, and most require a healthcare professional to administer. The FDA recommends checking your local or state health department websites for locations to get tested. You can also check with your healthcare provider about the option of an at-home rapid test.

Not sure if you should get tested?

Check out this Coronavirus Self-Checker by the CDC, an interactive tool that helps you determine if you should get tested or seek medical assistance.

How often can you take a rapid test?

Antigen tests can be done frequently, with some people taking them two or three times a week. Aspinall says it’s ideal for antigen tests to be used for those who are in contact with the public, or high-risk individuals, on a regular basis.

However, today there is a relatively limited supply of tests. Although nationwide distribution of rapid tests has increased, official recommendations are that it is only necessary to get tested if you are showing COVID symptoms or know you were exposed. Some clinics across the country are even administering tests only to those who are symptomatic.

“If someone’s at an increased risk for severe illness or has close contact with someone who’s at an increased risk for severe illness, I think getting tested regularly is smart,” Suzanne Pham, MD, medical director at Weiss Memorial Hospital in Chicago, told Health. “For those who are merely worried but don’t have a history of contact with anyone of concern and aren’t at an increased risk of severe illness, regular testing could strain the system and may take away the ability to test those who truly need it.”

How necessary are rapid tests?

According to Aspinall, rapid tests are absolutely essential. They are meant to be fast and frequent, which is vital during the pandemic both before and after an authorized vaccine becomes available.

“What’s interesting and unusual about this disease is that at least 50 percent—some say as much as 80 percent—of people have this disease and have zero symptoms,” said Aspinall. “You hear people say, ‘I was exposed but I feel fine.’ Well, it’s great that you feel fine, but it doesn’t mean you’re not infectious. And that’s why we need to be using these rapid tests more aggressively, to quickly say, you may feel fine but you still need to stay home.”

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