This guidance is intended for healthcare providers who order antigen tests, receive antigen test results, or perform point-of-care testing, as well as for laboratory and testing professionals and public health practitioners who perform antigen testing and reporting in a laboratory setting or at the point-of-care.
The purpose of this guidance is to support effective clinical and public health use of antigen tests for different testing situations.
This guidance incorporates considerations for people who are up to date with their vaccines and should be used in conjunction with CDC’s Stay Up to Date with Your Vaccines | CDC
This guidance focuses on the use of antigen tests to diagnose new infections. See CDC’s guidance on Quarantine and Isolation for testing to end isolation.
Guidance for individuals who are performing antigen self-tests can be found on CDC’s Self-Testing webpage
Antigen tests are commonly used in the diagnosis of other respiratory pathogens, including influenza viruses and respiratory syncytial virus (RSV). The U.S. Food and Drug Administration (FDA) has granted emergency use authorization (EUA) for antigen tests that can identify SARS-CoV-2. See FDA’s list of In Vitro Diagnostics EUAs.
Antigen tests are immunoassays that detect the presence of a specific viral antigen, which indicates current viral infection. Antigen tests are currently authorized to be performed on nasopharyngeal, nasal swab, or saliva specimens placed directly into the assay’s extraction buffer or reagent. The currently authorized antigen tests include point-of-care, laboratory-based, and self-tests. Certain tests have age limitations; refer to FDA’s website for more details. See Table 1 for additional information about antigen tests.
Antigen tests produce results quickly (within approximately 15–30 minutes), and most can be used at the point-of-care. Antigen tests for SARS-CoV-2 are generally less sensitive than real-time reverse transcription polymerase chain reaction (RT-PCR) and other nucleic acid amplification tests (NAATs), which detect and amplify the presence of viral nucleic acid. However, NAATs may remain positive for weeks to months after initial infection and can detect levels of viral nucleic acid even when virus cannot be cultured, suggesting that the presence of viral nucleic acid may not always indicate contagiousness.
Antigen tests and NAATs (when indicated) require proper interpretation for both accurate clinical management of people with suspected COVID-19, and for identification of people with infection when used for screening.
The clinical performance of diagnostic tests largely depends on the circumstances in which they are used. Both antigen tests and NAATs perform best if the person is tested when they are symptomatic. Although antigen tests generally have lower sensitivity compared to NAATs, they can also be used to test for infection with specific attention to the context in which they are used, described below.
Antigen test performance data have helped guide the use of these tests as screening tests in asymptomatic people to detect or exclude SARS-CoV-2 infection. See FDA’s recommendations for healthcare providers using SARS-CoV-2 diagnostic tests for screening asymptomatic individuals for COVID-19. Also see information from the Centers for Medicare & Medicaid Services (CMS) on the Updated CLIA SARS-CoV-2 Molecular and Antigen Point of Care Test Enforcement Discretion.
Antigen tests have been used for screening testing for COVID-19 in congregate settings such as nursing homes, dormitories, homeless shelters, and correctional facilities. Screening testing has quickly identified people with COVID-19, informing infection prevention and control measures, thus preventing transmission. In this case, and where rapid test turnaround time is critical, there is value in providing immediate results with antigen tests.
Healthcare providers and public health practitioners should understand test performance characteristics for interpretation of results, to recognize potentially false negative or false positive test results, and to guide additional confirmatory testing and management of the person tested. Laboratory and testing professionals who perform antigen tests should understand the factors that affect the accuracy of antigen testing, as described in this guidance. Healthcare providers, laboratory and testing professionals, and public health practitioners should also understand the differences among diagnostic, screening, and surveillance testing. See FDA’s FAQs on Testing for SARS-CoV-2.
This guidance supplements and is consistent with CDC’s Overview of Testing for SARS-CoV-2 and SARS-CoV-2 Point-of-Care and Rapid Testing guidance. CDC has also published guidance on SARS-CoV-2 Antigen Testing in Long Term Care Facilities, Interim Guidance for SARS-CoV-2 Testing in Correctional and Detention Facilities, Interim Guidance for SARS-CoV-2 Testing in Homeless Shelters and Encampments, and Guidance for COVID-19 Prevention in K-12 Schools.
