4 COVID-19 Questions: Why is COVID-19 testing so confusing?

Why is COVID-19 testing so confusing?

There has been a lot of talk about testing for COVID-19. There are tests to see if you’re sick and tests to see if you’ve been sick and have antibodies for the virus. There’s also been confusing messaging about when to get tested and what kind of test to get. And because COVID-19 is a new virus, everyone is having to learn these things quickly. It’s not surprising that testing is so confusing.

Types of COVID-19 tests

There are two types of tests: diagnostic tests and antibody tests.

Diagnostic Tests

Diagnostic tests identify the presence of the genetic material of the COVID-19 virus inside the mouth or nose of an individual. The diagnostic method most commonly used in COVID-19 testing (and for other viruses) is the PCR or swab test. This test tells a person that they either currently have or recently have had COVID-19.

The PCR test is performed by inserting a swab into the nose or mouth to obtain cellular material on the swab tip. Once this cellular material is on the swab, it is put into a machine that extracts the genetic material (RNA) from the cells. Following extraction, the RNA is multiplied many times through a technique called a polymerase chain reaction, or PCR. Now that the RNA has been multiplied many times, the test can identify the presence of the unique features of COVID-19 or SARS-CoV-2. Because SARS-CoV-2 is a novel strand of virus, the presence of these features indicates that you have recently been infected with COVID-19.

Antibody Tests

Antibody tests, also known as serology tests, are for people who have already recovered from a COVID-19 infection. An antibody test screens for the presence of antibodies that are formed when the body’s immune system fights off the infection. An antibody test is a simple blood test, but antibodies can only be detected after your body has cleared the infection. The presence of antibodies confers some type of protection from COVID-19. The absence of antibodies does not rule out other forms of immunity.

What testing can't tell us

The presence of a positive PCR swab is useful for diagnosing COVID-19, especially in those with symptoms. However, there are limits to what the PCR swab can do. It does not indicate whether you are infectious or not. In fact, people can have the presence of genetic material in their swab specimens up to 12 weeks after infection.

A PCR swab cannot tell you how long you have had COVID-19. It also cannot determine whether someone is still infectious after having COVID-19. It has been found that a non-hospitalized healthy person is no longer infectious or capable of spreading COVID-19 ten days after a positive test.

What now?

Testing for COVID-19 is available at each of our five Birmingham clinic locations. If you suspect you have COVID-19 and need to be tested, you can schedule a telehealth screening for same-day rapid testing.

To learn more about exposure to COVID-19, read the next post in our series about common COVID-19 questions, "I've been exposed to COVID-19. What should I do?"