COVID-19 Testing: The Basics
COVID-19 testing is a fast-growing field that is evolving as our understanding of SARS-CoV-2 improves and more test manufacturers enter the market. Whether you are taking a test prescribed by your doctor or choosing a test for your organization, it is important to choose the right type of test to give you the most useful information.
COVID-19 testing can be categorized into 2 main groups: testing for active SARS-CoV-2 infection or testing for past SARS-CoV-2 infection. Active infection indicates that a person has virus that is replicating and that they could infect others. Past infection indicates that an individual has recovered from COVID-19 and has no actively replicating virus.
To test for active infection, diagnostic antigen or molecular tests are used. Antigen rapid tests detect the presence of viral proteins (antigens) in a patient sample and can provide results in under a half hour. In contrast, molecular tests amplify existing viral genomic material from a patient sample. These tests can detect if a patient has a current infection, which can help patients and healthcare providers make decisions about treatment and isolation to reduce spread.
To test for past infection, serology tests are used. Serology tests detect the presence of antibodies produced by our immune system in response to a pathogen and are specific to certain proteins (antigens) of those pathogens. The presence of antibodies specific to SARS-CoV-2 indicates that a person was exposed to the virus and is currently seropositive for SARS-CoV-2-specific antibodies.