COVID-19 testing: How to choose the right test for you


by David Winter, MD

Jan 12, 2021

Information and guidance about COVID-19 care and vaccination continues to evolve. Please refer to the Centers for Disease Control and Prevention for the latest.

What should you do if think you have been exposed to COVID-19, or SARS CoV-2? With a handful of options available for coronavirus testing, there is quite a bit of confusion about what to do if you think you have COVID-19 symptoms or were exposed. 

Let’s try and simplify this.

Stay smart and stay home

First things first, if you are exposed or potentially exposed to the virus, what should you do? 

One option is to quarantine. New guidelines from the Centers for Disease Control and Prevention (CDC) tell us that if you can isolate for 10 days and remain free from COVID-19 symptoms, you are not likely to be contagious even if you had contracted the virus. You should continue to wear a mask, physical distance and wash your hands, of course. 

Additionally, for a total of 14 days from exposure, you should minimize contact with others — we call this time from exposure to symptoms the “incubation period,” and it can last up to two weeks — though that is not usually the case. Calculations by the CDC conclude that at 10 days after COVID-19 infection, asymptomatic individuals have only a 1 percent chance of spreading the virus. 

Questions about the safety of the COVID-19 vaccine? Get the answers.

Finding the right COVID-19 test for you 

PCR viral test 

The very best COVID-19 test is called the PCR viral test; it looks for genetic material from the virus itself. If positive, you can bet on having the virus! 

One issue is that the COVID-19 test may not be positive right after exposure. It takes several days for enough virus to replicate, and maximum sensitivity is said to be five days after being exposed. 

The sampling technique also weighs in here, with deep nasal swab being the most likely to detect the virus if it is there. It is important to note that cheek swabs and saliva specimens are less sensitive. 

You may be wondering, “how long does it take to get COVID-19 test results?” The PCR test takes time to deliver results — typically a day, but when labs are overloaded with tests, the time to receive COVID-19 test results can extend to several days.

Point of care test

What about the rapid tests, commonly called point of care tests?  These test for remnants of the virus and can be done in as few as 15 minutes. When positive, they are reliable, but when they are negative, you could still be harboring the COVID-19 virus and still be contagious.

COVID-19 antibody test

These tests look for antibodies that your body may have produced in response to infection from the virus. A COVID-19 antibody test is not a good test for new cases, as it may take a week or longer to turn positive. 

Some use this test to see if they may have had the infection in the past and now have immunity, but at this point in time that answer is not clear. There have been cases where a patient had COVID-19, tested positive for antibodies and got infected again.

COVID-19 testing is complicated; fortunately, prevention is easier. Following the three W’s — wearing a mask that properly covers your nose and mouth, watching your distance and washing your hands — is the best form of prevention. Avoiding infection is always easier than treating, and easier in many cases than detecting with COVID-19 tests.

For more information about the COVID-19 virus, COVID-19 symptoms  and what you can do to keep yourself healthy, subscribe to the Scrubbing In newsletter.

About the Author

David Winter, MD, is an internal medicine physician on the medical staff at Baylor Scott & White Signature Medicine – Tom Landry.

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