Offering free at-home COVID-19 testing. How and when should you use them?

At-home COVID-19 testing, also known as rapid antigen testing, is convenient and accessible, and now American families can once again order four free tests. Be careful though. Test results may be wrong. Learn when and how to use testing.

Millions of people living in the United States have ordered free at-home COVID-19 tests. Starting September 25, 2023, every American household can again order four free tests.

Ordering a test takes less than a minute. Just visit the popular covid.gov/tests website . Then fill in your address and your free at-home COVID-19 test should arrive within a week or two. Currently, every household in the United States is entitled to four free at-home COVID-19 tests. People living in poor or low-income communities should have access to more free coronavirus testing.

Easy, right? 

Well, ordering a test is quick and easy. But figuring out when and how to use them or how to understand your results isn't always simple. That's because at-home COVID-19 tests, also called rapid antigen tests, are not as accurate as the more reliable nasal swab PCR tests you can get at a doctor's office. PCR stands for polymerase chain reaction. ( Learn more about getting a PCR test .)

The appeal of at-home COVID-19 testing is its convenience and accessibility. You can take the test at home (hence the name) and get results in about 15 minutes. But it's important to be cautious about rapid home test results and how you use them. If you get a positive result, the test is probably accurate. If your result is negative but you get sick, you may still have COVID-19. 

To help you understand what an at-home COVID-19 test is and how to interpret the results you get, we spoke with Dr. Michelle Barron, senior medical director of infection prevention and control at UCHealth and a professor of medicine and infectious diseases at the university . University of Colorado School of Medicine .

What is an at-home COVID-19 test?

Home tests detect proteins in the virus that causes COVID-19. These proteins are called antigens, which is why rapid at-home tests are called antigen tests or rapid tests. They don't have to be sent to a lab to get results. Typically, people can see results in about 15 minutes. PCR tests, on the other hand, test for the genetic material of active viruses. Samples for these tests need to be analyzed in a laboratory. This can take several hours or even days, depending on how busy the lab is.

Home Follicle Stimulating Hormone FSH Test Kit

Are at-home tests reliable?

The at-home test is about 80% accurate. While 80% sounds good for an algebra test score, it's not perfect for a COVID-19 test. This means that when a person is infected with COVID-19, 20% of the time, or one in five times, the test will not detect evidence of the virus. This is called a false negative result. And if people mistakenly use false negative results from rapid at-home tests, it could endanger the elderly, people with cancer or those with compromised immune systems who are at high risk.

That's why Barron and other medical experts urge people to be cautious about these tests.

Here are Barron's basic guidelines for interpreting at-home COVID-19 test results:

• If you feel sick and get a negative result, don't assume the rapid at-home test is accurate.
• If you have been in close contact with someone who has tested positive for COVID-19 and you feel sick, please do not assume that the rapid at-home test is accurate . If you have been in close contact with someone who has tested positive for COVID-19 and you develop any symptoms, you most likely have COVID-19.
• It is important to assume that a positive result from a home test is accurate. If your rapid antigen test shows you have COVID-19, you probably do. Barron said false-positive results are uncommon when testing for COVID-19 at home.

"Use your common sense," Barron said. "If you have symptoms, do not take a negative at-home test result as a free pass to go out. If you have a sore throat, runny nose, headache, or any other COVID-19 symptoms and your test result is negative, you are likely infected COVID-19, and testing is missing that.”

Barron encouraged people to continue using the safety protocols that have been in place since the start of the pandemic. If you feel uncomfortable, be considerate and friendly. If you have symptoms of illness, whether you think it is COVID-19, the flu, or just a cold, please stay home and do not spread it to others. People who are sick should not go to work, go to the gym, fly or attend social gatherings.

If I test positive for COVID-19 at home, are the results likely to be correct?

Yes. A positive COVID-19 test result taken at home may be accurate.

If I test positive for COVID-19 at home, do I need a PCR test to confirm my positive test result?

Won't. If your test result is positive, it can be assumed that you have COVID-19.

What should I do if I test positive for COVID-19 at home?

• If you have any serious symptoms, such as difficulty breathing, call 911 for help immediately. 
• If you do not have severe symptoms, you should self-isolate at home, stay hydrated, and use over-the-counter medications if needed . 
• If you detect an infection early, call your doctor. You may receive a prescription for a drug called Paxlovid, which can shorten the course of your illness.
• If you are older, immunocompromised, pregnant, or in another high-risk group and you test positive at home, contact your healthcare provider immediately. 

Why are at-home COVID-19 tests showing so many false negative results?

At-home COVID-19 tests produce a high rate of false negative results because they are less sensitive than PCR tests. The accuracy of PCR testing is close to 99%. Antigen tests do not detect all COVID-19 infections, but timing is also important. People sometimes test negative because they took a rapid test at home too early in their illness. Or, they may not be wiping themselves properly.

How to get tested for COVID-19 at home?

Follow the instructions for the at-home test. Typically, at-home testing requires people to swab their nose to obtain a sample. As at-home COVID-19 tests have been in short supply across the United States, there have been reports of families sharing one at-home test. Do not do this. The tests don't work, and it's unhygienic to test multiple people with one swab.

Do at-home COVID-19 tests expire?

Yes. Rapid tests do expire. However, some validity periods have been extended. View more information about the expiration date of at-home COVID-19 tests .

If you think you have COVID-19, or you have been exposed to someone who has tested positive, when is the best time to get a rapid at-home test?

• If you are asymptomatic, wait approximately five days before taking a home test.
• If you do develop symptoms and you have been exposed to someone with a confirmed case of COVID-19, you can assume that you also have the disease because the disease is very contagious and omicron transmission is very widespread. If you think you have COVID-19, please self-isolate to avoid spreading the disease.

"Unless you have symptoms, wait at least 72 hours and preferably five days before getting tested," Barron said.

The reason she recommends waiting to get tested (unless you have symptoms) is because tests cannot detect COVID-19 infection right away.

"Suppose I have COVID-19 and I cough on you. You don't suddenly become positive within an hour. With omicron, the infection accelerates faster. However, it doesn't happen overnight. It takes a few days time," Barron said.

If you have symptoms, you can go ahead and get tested, or simply assume you have COVID-19 and act accordingly.

"If you have symptoms, you are more likely to have COVID-19 than any other illness," Barron said.

Who should get tested for COVID-19?

People who are at high risk for severe consequences from COVID-19 should get tested. Others may need to get tested before going to work, school or traveling.

People undergoing medical procedures sometimes need to be tested for COVID-19. 

People with common symptoms of COVID-19 may need to get tested. By now, the symptoms of this disease are very familiar. They include: fever, shortness of breath, new cough, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion or runny nose, nausea, vomiting, or diarrhea. Of course, the symptoms are also similar to those of the flu.

In general, if you are sick, stay home and do not spread your illness to others. If you need confirmation if you have COVID-19, use a rapid test or call your doctor's office.

When does it make sense to use a rapid at-home COVID-19 test?

If you're hosting a family birthday party and an older relative is attending, the first step is to make sure everyone who comes is vaccinated. Learn more about getting the new COVID-19 vaccine this fall.

Then, if someone is feeling unwell, you need to discuss it ahead of time. Anyone with any symptoms of illness should not attend gatherings of any kind. COVID-19 rates are likely to climb this fall and winter as they have in past years.

If you are hosting a smaller vaccination gathering, after screening for those who are sick, you may consider having everyone take a rapid test before attending the gathering. However, it is important to know that the results do not guarantee that every guest will be negative for COVID-19. And you shouldn't use these results to determine whether it makes sense to include vulnerable people at your party. You have to weigh the potential risks and decide what makes sense

Barron cited an example from her family. About two days after reuniting with her parents, a relative tested positive for COVID-19. Family members are fully vaccinated and wear masks at public events. Barron's parents asked if they should get tested immediately. Barron encouraged families to monitor symptoms and wait at least 48 hours before getting tested. If a family member takes a rapid at-home test and gets a positive test result, it means they have COVID-19. However, a negative result from a home test does not mean they are free of infection.

In the meantime, she encouraged parents not to attend large group events.

“You don’t want to go to the YMCA and take a dance class with a bunch of seniors,” Barron said.

Barron said people should get tested, preferably with a PCR test, about five days after exposure or if they develop symptoms.

What are the benefits of taking a rapid COVID-19 test at home?

Barron said one of the biggest potential benefits of rapid at-home testing is accessibility. 

It's much easier to get tested at home than to go to the doctor's office. Home testing is also useful for people living in rural or remote areas.

For many people, it is very convenient to have a test mailed directly to every address in the United States. Four tests per home won't last long. People should be aware that false negative results are common. 

"Use tests wisely. Understand the limitations of what they can and cannot do," Barron said.

With an at-home test, could you test negative in the morning and test positive later in the day?

Yes. All COVID-19 tests can only give results that amount to a snapshot in time.

Therefore, it makes sense to wait until about five days after developing symptoms or being exposed to someone who tests positive for COVID-19 to get tested. Testing immediately after exposure does not do much good. 

"You're just trying to reassure yourself, but you're not really reassuring yourself," Barron said.

Can U.S. citizens living abroad order four free at-home rapid tests?

Those serving in the military and diplomatic missions overseas can take four tests at home for free. People living on U.S. soil are also eligible.

What brands will people be tested on?

As the old saying goes, "You get what you get." With the federal program, you won't be able to choose a brand for the free tests you receive. But all rapid antigen tests that federal officials will ship are fully authorized by the U.S. Food and Drug Administration (FDA).

How will the test be conducted?

U.S. Postal Service workers will provide four free tests to American households. Tests are expected to arrive approximately 7 to 12 days after you place your order.

Do some states actually offer free at-home COVID-19 testing to individuals?

Yes. Check with your state's public health agency and learn more about Colorado's plan to provide people with rapid home testing .