The high demand for COVID-19 tests continues, along with questions about the various types of tests and when to use them.
A few types of COVID-19 tests are available to help you identify if you have COVID-19:
Polymerase chain reaction test
A polymerase chain reaction (PCR) test looks for the virus' genetic material in a patient's sample. The sample is collected by inserting a swab into a person's nostril and taking cells from the back of the nose or in the person's saliva.
If you take a PCR test, you can expect to receive results in one to four days, depending on the lab. These tests have a high level of accuracy.
If you test negative for COVID-19 using a PCR test, you are likely not infected, provided you do not have any symptoms. If you do not have symptoms of COVID-19 and do not have a known exposure to a person infected with COVID-19, you do not need to quarantine. Continue to wear a surgical/procedural mask in all public settings.
If you test positive for COVID-19 using a PCR test, follow these Centers for Disease Control and Prevention (CDC) guidelines:
- Stay home for at least five days.
Day zero is your first day of symptoms or a positive viral test. Day 1 is the first full day after your symptoms developed or your test specimen was collected. Stay home for five days and isolate from others in your household. Wear a tight-fitting mask when around others. If you don't have symptoms, you can end isolation after five full days. If you have symptoms, you can end isolation after five full days if you are fever-free for 24 hours without the use of fever-reducing medication and your other symptoms have improved. Check with your employer, school district or public health department for exact isolation guidelines for you or your family, as those guidelines may vary in your community.
- Wear a mask.
After the end of your isolation period, wear a surgical or procedural mask in all public settings for at least 10 days.
- Tell your healthcare provider.
Contact your healthcare provider so your COVID-19 positive test can be documented in your health record. At Mayo Clinic, patients can do this by sending a secure message using Patient Online Services the patient portal. Tests that were completed at a Mayo Clinic location are automatically entered into the patient's health record.
If you still have a fever, regardless of how many days you've been in isolation, continue to stay home and monitor your symptoms until you no longer have a fever.
You may need to have a negative COVID-19 test result ― either a PCR or at-home antigen test ― before you can return to work or school. Check with your employer, school district or public health department to determine if this is needed.
Rapid at-home antigen test
Rapid at-home antigen tests detect certain viral proteins in a nasal sample using a nasal swab. While antigen tests can produce results in 15 minutes, the chance of false-negative results increases.
If you take an at-home COVID-19 antigen test and your results indicate you are positive for COVID-19, here are answers to common questions that will help determine your next steps:
Can you trust the results of an at-home antigen test?
If you have symptoms of COVID-19 and the at-home antigen test result is positive, you likely have COVID-19 and should isolate, per Centers for Disease Control and Prevention (CDC) guidelines. Sometimes an at-home antigen test can have a false-negative result. This means the test incorrectly indicated that you don't have COVID-19 when you do. The antigen test may have missed signs of an early infection.
A negative at-home test is not a free pass. If you are experiencing symptoms and the at-home antigen test result is negative, it's a good idea to get a lab-based PCR test for COVID-19 and influenza. You also should stay home and isolate until PCR test results are available.
How long do you need to stay in isolation if you test positive for COVID-19 using an at-home COVID-19 antigen test? Is isolation time the same as for a PCR test?
Generally, if you are positive for COVID-19, by either the COVID-19 antigen or PCR test, you will need to be in isolation for a minimum of five days from the onset of your symptoms or a positive test for COVID-19.
Do you need to have another PCR COVID-19 test completed before you return to work or normal activity following the five days of isolation?
You may need to have a negative COVID-19 test result ― either a PCR or at-home antigen test ― before you can return to work or school, depending on specific requirements for the organization and where you live.
Should you let your local health care provider know you tested positive for COVID-19 with an at-home antigen COVID-19 test?
Yes. You should let your local healthcare provider know that you tested positive for COVID-19 using an at-home antigen test. At Mayo Clinic, you can do this by submitting a photo of your positive antigen test result to your care team in secure message using the patient portal. This will ensure your care team can help you with any care needs related to COVID-19 if you continue to have prolonged symptoms of COVID-19 or if you need to seek additional care related to COVID-19.
If you tested positive for COVID-19 using an at-home antigen test and receive your care from another health care organization other than Mayo Clinic, contact your local healthcare provider so your positive result can be documented.
Do you need to take another at-home COVID-19 antigen test to make sure you're negative after a certain amount of time to make sure you no longer have COVID-19 before you return to normal activity?
No. If you no longer have symptoms after five days or are fever-free for at least 24 hours without using fever-reducing medication, you do not need to take another COVID-19 test to confirm you are no longer positive, unless you have been directed by your workplace or school. However, if your symptoms persist longer than five days, you should remain isolated until you no longer have symptoms for at least 24 hours.
Does your entire household need to be tested to make sure they are not positive following my positive at-home COVID-19 antigen test?
No. If others in your household do not have any COVID-19 symptoms, they do not need to be tested. However, if they experience symptoms, they also should be tested.
If someone in your family also tests positive using an at-home COVID-19 antigen test, do you need to quarantine again even though you've already had a positive COVID-19 diagnosis?
If a member in your household tests positive for COVID-19, and you also tested positive for COVID-19 within the last 90 days, you do not need to quarantine based on guidance from the CDC.
Information in this post was accurate at the time of its posting. Due to the fluid nature of the COVID-19 pandemic, scientific understanding, along with guidelines and recommendations, may have changed since the original publication date.