Types of COVID-19 Tests

COVID-19 tests come in a variety of forms and can be used to confirm a current infection or identify people who may have the disease but don’t show symptoms.

Molecular Tests

Molecular tests are a wide variety of laboratory techniques that examine the genetic material (DNA and RNA) inside a person’s cells. A molecular test analyzes changes in these two types of molecules to look for red flags that may indicate a disease. One of the most common COVID-19 molecular tests is a real-time reverse transcriptase polymerase chain reaction (RT-PCR). It combines a type of enzyme called polymerase with a probe that can read a strand of RNA and make a DNA copy. A PCR test is highly specific and sensitive. However, it requires special equipment and trained personnel to perform. It takes 1 to 3 hours for a sample to be run, and it requires RNA extraction before the result can be seen.

Antigen Tests

Antigen tests (also known as rapid tests) look for specific proteins on the surface of the COVID-19 virus without amplifying or replicating them in the lab. They can be done with a nasopharyngeal swab and are often given to people in the early stages of infection. These tests are fast and easy to use. However, they can be less accurate than PCR tests. They can miss very early infections, because not much virus is in the nasal and throat areas where the swabs are taken. They also have a higher chance of generating false-negative results — meaning that you could still be infected if the test is negative. Depending on the situation, your health care provider may recommend another type of test to confirm that you have COVID-19.

RNA Tests

Several types of RNA Tests are available to detect COVID-19, including real-time reverse transcriptase quantitative polymerase chain reaction (rRT-qPCR) and loop-mediated isothermal amplification (LAMP). These methods require special equipment and trained lab personnel to run. RT-qPCR is an extremely sensitive testing method that uses a series of temperature changes to create copies of viral DNA in the sample. It can amplify genetic information up to a billion times before the sample is no longer detectable. The sensitivity of RT-PCR can be a disadvantage because it can pick up small amounts of virus very early in an infection. This means it can miss pre-symptomatic or asymptomatic COVID-19 infections and can also cause false positives among people who have cleared their virus infection and are no longer contagious. LAMP tests are newer and not as well developed, but they can quickly detect if someone is infected with COVID-19. They are cheaper than RT-PCR, can be done in hospitals and can produce results within 2-3 hours.