Using rapid antigen tests to test for COVID-19

Questions concerning the numerous rapid antigen tests and when to utilize them, as well as the strong demand for COVID-19 testing, persist. The director of Clinical Virology at Mayo Clinic, Matthew Binnicker, Ph.D., breaks down the various testing choices and explains how they operate.

Nasal swab polymerase chain reaction test

This test, which is carried out in a testing facility or a doctor’s office, searches for the RNA of the virus in a patient’s sample. An individual’s nostril is tapped with a nasopharyngeal swab to extract cells from the back of the nose for use as a sample. Patients may spit into a tube during several laboratory procedures to provide a sample of their saliva.

Nasal swab polymerase chain reaction test

If you have been exposed or are exhibiting symptoms, schedule a visit with your doctor.

You may anticipate receiving your findings within 24-72 hours, depending on the lab your physician employs. When it comes to COVID-19 testing, the polymerase test is considered the gold standard.

Nasal swab at home with a polymerase chain reaction test conducted at a lab

Similar rapid antigen tests are performed in the doctor’s office, however, in this instance, the patient gathers the nose swab themself and mails it to a lab for examination.

When symptoms first appear or soon after exposure, patients should take this test.

It usually takes three to seven days for at-home testing to provide results. Compared to at-home antigen testing, the findings of these polymerase chain reaction rapid antigen tests are more accurate since they are done in a lab.

Polymerase chain reaction test for saliva

Similar rapid antigen tests are conducted in the doctor’s office, but in this case, the patient gathers the saliva sample and mails it to a lab for analysis. Saliva is a specimen that may be obtained for polymerase chain reaction testing, much as swab rapid antigen tests. Comparatively speaking to a nasopharyngeal swab, collecting saliva from patients is often simpler and more pleasant.

Polymerase chain reaction test for saliva

After exposure or when symptoms start, patients should utilize this test.

It usually takes three to seven days to get results from at-home, mail-away testing. Compared to at-home antigen testing, the findings of these polymerase chain reaction rapid antigen tests are more accurate since they are done in a lab. You can also read about What is a COVID-19 Rapid Antigen Test by visiting

Rapid antigen tests at home

Certain viral proteins are discovered in the nasal sample by quick at-home antigen assays.

Patients should aim to do this test on the day of the event in order to get the greatest information on whether they have high levels of the virus in their system at that time. Timing is crucial with this test, so patients should strive to do so. Antigen testing using a nasal swab may provide findings in 15 minutes.

These rapid antigen tests are quicker and less costly than polymerase chain reaction testing, and they may be purchased anywhere at-home rapid antigen tests are marketed. However, there is a higher possibility of false-negative findings with these rapid antigen tests. Patients should continue to use a mask in public places and while near others who are unvaccinated or at high risk of contracting the illness, even if an at-home antigen test is negative.

Patients should have a lab-based polymerase chain reaction test the same day or the next day if the at-home test results in a positive result so that public health authorities may monitor the case and link the patient with a healthcare professional who can assess if treatment is required.

Analyses of antibodies

A serology or antibody test looks for antibodies in your blood that defend against the COVID-19 virus. After being sick or receiving a vaccination against an illness, your immune system produces proteins known as antibodies. For a while following, they may aid in preventing infection or serious sickness if you do get infected. The duration of this protection varies depending on the condition and the individual.

Rapid antigen tests shouldn’t be used to determine if someone is currently infected with the COVID-19 virus. Because it might take your body 1–3 weeks to produce antibodies following an infection, an antibody test may not be able to detect a present illness.

Analyses of antibodies

You could continue to test positive for a while after receiving a positive test result. After your first positive result, you can test positive for antigens for a few weeks. NAAT results might remain positive for up to 90 days. It might be challenging to determine if positive test results in a new infection since reinfections can happen within 90 days. If you have any queries or worries about your particular situation, think considering speaking with a healthcare professional.

How to interpret the outcome

If Your COVID-19 Test is


Any COVID-19 test that is positive indicates that the virus has been found and that you are infected.

  • To prevent others from contracting the infection, isolate yourself and take measures, such as wearing a premium mask.
  • Let others you’ve recently interacted with know they could have been exposed.
  • Keep an eye on your symptoms. Seek emergency attention right away if you experience any emergency warning symptoms.
  • You could think about getting in touch with a doctor, a community health center, or a pharmacy to find out what treatment alternatives might be available to you. To be successful, treatment must be started within a few days after the onset of symptoms.

o If you are an older adult or have a pre-existing medical condition, you are more likely to get very ill. You might perhaps be eligible for therapy.


A negative COVID-19 test indicates that the virus was not found, but it does not rule out the possibility that you may still be infected. FDA guidelines for repeat testing are available if you utilized an antigen test.

If you have symptoms,

  • You might have COVID-19 but were diagnosed with another sickness or you could have tested negative for the virus.
  • Practice normal measures for the public’s health to avoid infecting others.
  • If you have any concerns about your test results or if your symptoms become worse, get in touch with a medical professional.
  • If you were exposed to the virus that causes COVID-19 but do not yet have symptoms, you should keep taking the suggested precautions.
  • You may resume your usual activities if you don’t have any symptoms and haven’t been exposed to the COVID-19 virus.
  • Keep taking precautions to safeguard both you and other people, such as keeping an eye out for signs. If symptoms develop, get retested.

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