COVID-19 and Diagnostics
Rapid detection of COVID-19 cases in the United States requires wide availability of testing. On February 4, 2020, the Secretary of Health and Human Services determined that there is a public health emergency and that circumstances exist justifying the authorization of emergency use of unapproved in vitro diagnostics for detection and/or diagnosis of the novel coronavirus.
In vitro diagnostics are tests performed on samples taken from the human body, such as swabs of mucus from inside the nose or back of the throat or blood taken from a finger prick or drawn by a phlebotomist. In vitro diagnostics can detect diseases or other conditions and can be used to monitor a person's overall health to help cure, treat, or prevent diseases.
The term "diagnostic test" is generally used to refer to molecular or antigen tests, both of which can be used to diagnose infection with the SARS-CoV-2 virus.
Molecular tests identify the virus in samples from the respiratory system and can be used to diagnose illness. Some tests are conducted at the testing site you visit with results available to you within minutes. Other tests must be sent to a laboratory for analysis, a process that may take one or more days once the lab receives your samples. Molecular tests include PCR (polymerise chain reaction) tests, which are considered to be the most accurate.
Antigen tests detect the presence of viral proteins found on the surface of the SARS-CoV-2 virus. While antigen testing is not new, at this time, only the following antigen test(s) have been issued an Emergency Use Authorization (EUA) for SARS-CoV-2. This test also uses specimens taken from mucus swabs. Emergency use of this test is limited to authorized laboratories and other authorized testing locations.
You can learn more about risk, symptoms, and diagnostic testing here.
Serological or Antibody Tests
The terms "serological" or "antibody" generally refer to blood tests that detect antibodies to the SARS-CoV-2 virus. Because the antibodies are part of the body's immune response to exposure and not the virus itself, such testing should not be used to diagnose infection but can help identify whether an individual has an adaptive immune response to SARS-CoV-2. Such a response would indicate recent or prior infection by detecting antibodies to SARS-CoV-2 in human blood specimens. Researchers are working to determine if the antibodies indicate immunity to the virus, and if so, how long that protection from reinfection might last.
Regulation of Tests
The U.S. Food and Drug Administration is responsible for regulating medical devices such as diagnostic tests. During this emergency, some tests have been issued Emergency Use Authorizations. You can find a list of those tests here.
Lab tests, and the laboratories that run tests, vary in level and complexity. Simple tests with a very low risk of error can be run in nearly any FDA-certified lab, such as one in a primary care office, and some tests (although none for COVID-19 yet) are even approved for use at home. These are labeled as W when you click on the test link above.
You will also see tests marked as M and H, representing Moderate Complexity and High Complexity labs. As tests become more complex, so do the labs that process the tests and where they might be available. These designations basically let you know that those tests require more specialized handling, which may include higher levels of training, materials/equipment, experience, and proficiency. In some cases, the High Complexity labs may be the labs that actually developed the test.
Use the links below to learn more about diagnostics and testing.
Diagnostic Tests for COVID-19 – Answers to frequently asked questions, including information on tests available for detecting SARS-CoV-2 and a list of organizations offering testing and/or test kits
Emergency Use Authorizations – Lists current and terminated EUAs that make available diagnostic and therapeutic medical devices to respond to public health emergencies
EUA Authorized Serology Test Performance – FDA summarizes expected performance of authorized tests
Medical Devices and the COVID-19 Pandemic – Information from FDA about medical devices used to diagnose, prevent, and treat COVID-19
Policy for Coronavirus Disease-2019 Tests – Immediately in effect guidance from FDA for clinical laboratories, commercial manufacturers, and FDA staff
Thermal Imaging Systems and COVID-19 – FDA answers questions about using thermal imaging systems during COVID-19