What is an Antigen? How does it work?

Antigens are molecules, such as proteins, that are foreign to your body. They can cause your immune system to produce antibodies to them. Antigen tests are used to identify foreign proteins. These are structural or functional components that are specific to a pathogen. This test gives a definitive answer to whether the patient has the pathogen. The test will determine if the target antigen is present at sufficient levels in the patient sample. This allows healthcare professionals to quickly diagnose conditions such as strep and flu from the point of care in minutes.

What are the advantages of antigen testing? SARS-CoV-2 antigen tests can be used in combination with molecular testing or as an alternative. They can provide solutions to the greatest challenge we face today: scale. The cost of antigen testing is relatively low and can be used to help healthcare system combat COVID-19. Laboratories-based antigen tests can reduce cost and errors. Interpretation errors may be eliminated through automation. They also have fast turnaround times and high test throughput. The benefits of rapid tests are that they can easily be distributed in a community. This includes non-traditional settings such as schools and nursing homes. These areas could benefit greatly from having access to test results at the point where care is provided. The rapid turnaround of results makes it possible to quickly act on the results in real time. Rapid antigen test can be used to reduce the spread of the disease in areas where the virus is high. A patient can self-quarantine within minutes, rather than waiting for lab results and possibly infecting others.

Antigen tests should be used when necessary. Antigen tests work best when the person’s viral load, which is usually at the beginning stages of infection and when patients are not symptomatic, is high. These tests are especially useful in congregate settings such as schools and nursing homes where rapid and repeated testing can be used to reduce the spread of the virus. Antigen tests generally have a high level of specificity. This refers to the test’s ability generate negative results for those who do not have the disease you are testing. High-specificity tests will not produce false positives and do a great job of excluding people who aren’t affected by the disease. It is important to remember that antigen tests may not be as sensitive as PCR tests. These tests amplify the target virus DNA or RNA sequence to produce a quantifiable signal that indicates the presence of the virus within a sample. To make up the possible decrease in antigen test sensitivity, negative results should be combined with additional patient factors such as COVID-19 history and clinical symptoms.