What assessments can be found to detect COVID-19?
There are currently three types of COVID-19 tests authorized by the US Food and Drug Administration (FDA):
- Molecular tests are used to detect the genetic material of SARS-CoV-2, the virus that causes COVID-19. Molecular tests are fairly accurate and can be used to diagnose the disease.
- Antigen tests are a new category of tests that can quickly detect fragments of the virus from nasal swabs. Antigen tests can provide results in minutes, but they are not as sensitive as molecular tests. Positive results from antigen tests are highly accurate, but negative results may need to be confirmed with a molecular test.
- Antibody (or serology) tests detect the body’s immune response to COVID-19 by looking for antibodies in the blood to help determine prior exposure. When the body is fighting an infection or has fought an infection, antibodies can be found in the blood. These tests do not detect the actual virus but are used to identify people who have been infected with the virus in the past.
FDA has issued an emergency use authorization for home use with self-collected nasal swab samples in individuals age 14 years and older who are suspected of COVID-19. The self-administered test, which requires a prescription, can provide rapid results at home or in a medical setting.
More than 285 tests have been authorized for emergency use including 224 molecular tests, 58 antibody tests, and 7 antigen tests. Accuracy varies among all of the tests. The resulting uncertainty can complicate public health decisions.
Some antibody tests have a high potential for false-negative and false-positive results. They may not be able to detect antibodies in the blood of someone who is newly infected, and they may not be able to distinguish SARS-CoV-2 from other coronaviruses. The presence of antibodies may indicate immunity from COVID-19, but that has not yet been conclusively proven; nor do scientists know the duration of protection. Although serologic tests should not be used at this time to determine if an individual is immune, these tests can help determine the proportion of a population previously infected with SARS-CoV-2 and provide information about populations that may be immune and potentially protected.
Serologic test results should not be used to make decisions about returning to school or the workplace. Additional data are needed before modifying public health recommendations based on serologic test results, including decisions on discontinuing physical distancing and using personal protective equipment.