Antigen testing is a diagnostic method used to detect specific proteins, known as antigens, from pathogens like viruses. This type of test is commonly used for identifying infections, such as COVID-19, by providing quick results, often within 15 to 30 minutes. Antigen tests are typically performed using a nasal swab or saliva sample. These tests are generally less sensitive than PCR tests, which means they may not detect all infections, especially in individuals with low viral loads. However, antigen tests are valuable for rapid screening and can help in controlling outbreaks by identifying infected individuals quickly.