Polymerase chain reaction (PCR) tests
The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) considers PCR tests the “gold standard” of COVID-19 testing.
Samples are usually taken through nasal or throat swab, but saliva samples can also be used. This test identifies your current state of infection. It will determine if you are contagious and need to quarantine yourself.
Because timing is a factor with this type of test, the best time to get tested with the PCR test is approximately five days after exposure to the virus.
A follow-up test is usually not needed. If your test result is negative and you are developing symptoms, you should get tested again for clarification.
Antigen tests aim to identify specific proteins on the surface of the virus.
Antigen tests can be done very quickly, using saliva or a nasal swab.
Though antigen tests are faster and can be easily scaled up, they have a high false-negative rate — with as many as half of negative results inaccurate.
Results can be produced in as little as 15 minutes.
Antibody tests identify whether an individual has had an immune response after a COVID-19 infection.
These tests do not detect active infections. Additionally, results will only determine whether you have had the virus, not if you are immune. There is no proof of guaranteed immunity for COVID-19.
Depending on the technology used for testing, turnaround times can be anywhere from 2-10 hours. A follow-up test is usually not needed. If your test result is negative and you are developing symptoms, you should get tested again for clarification.
Neutralization assays set the standard for coronavirus serologic testing. During testing, neutralizing antibodies are measured by a plaque reduction neutralization test (PRNT).
The PRNT utilizes the ability of a specific antibody to neutralize a virus, in turn preventing the virus from causing the formation of plaques.
Turnaround times can range from a few to several days, and PRNTs require a specialized facility.