what is an antigen test

An antigen test is a diagnostic tool that detects the presence of a specific viral antigen, which suggests current viral infection. It is a rapid diagnostic test that directly detects the presence or absence of an antigen. Antigen tests are commonly used in the diagnosis of respiratory pathogens, including influenza viruses and respiratory syncytial virus (RSV). They are less invasive than other diagnostic tests and return results within 10-30 minutes. Antigen tests are a type of lateral flow test that detects antigens, rather than antibodies or nucleic acid. They work by detecting specific proteins, called antigens, on the surface of the virus. Antigen tests are better at detecting a SARS-CoV-2 infection when someone has COVID-19 symptoms compared to if they do not. They are less likely to detect the SARS-CoV-2 virus than molecular tests, such as polymerase chain reaction (PCR) tests and other nucleic acid amplification tests (NAATs), which detect genetic material called RNA from the virus. However, they are quick to implement with minimal training, offered significant cost advantages, costing a fraction of existing forms of PCR testing and give users a result within 5–30 minutes. Antigen tests have found their best use as part of mass testing or population-wide screening approaches.