There are two kinds of tests used in Australia to detect COVID-19, these are known as diagnostic and screening tests. A rapid antigen test is a screening test that is used to potentially identify positive cases earlier to help reduce the spread of the virus and prevent outbreaks. When used regularly, rapid antigen test help identify individuals who may be infectious early on. These individuals can be pre-symptomatic or asymptomatic but still carry the virus and may transmit it to others.
A standard polymerase chain reaction (PCR) test is a diagnostic test, and can confirm if someone has COVID-19, with results available in approximately 24 hours. These tests take a deep nasal sample and throat sample and are tested in laboratories.
Rapid antigen testing is a screening tool to help detect COVID-19 in those without any COVID-19 symptoms. The test generally involves a nasal/saliva swab (using a small cotton bud) that is placed into a chemical solution. The results are then displayed on the device within 10 to 15 minutes.
Benefits of rapid antigen testing
Rapid antigen tests have been used internationally and in some Australian industries enabling them to perform easy screening with results available within minutes.
However, these tests have some limitations compared to the standard COVID-19 test (PCR) used at testing clinics.
Accuracy rate
Rapid antigen tests will detect most cases of COVID-19 but are not as accurate as the standard test (PCR). Rapid antigen tests can detect the virus in the acute phase of infection, especially in the week before symptoms are apparent. In the Australian community where there are low rates of COVID-19, the tests are less accurate as there is a higher risk of both false positive and false negative results. If you develop symptoms or are identified as a close or casual contact of someone who has COVID-19, you must get tested at a clinic to receive a PCR test and self-isolate.
A positive rapid antigen test doesn’t mean you necessarily have COVID-19, it means you need to get a standard (PCR) test straight away to confirm the result.
What to do if you get a positive test result?
If you get a positive rapid antigen test result, you must immediately get a standard COVID-19 test (PCR) at a testing clinic to confirm the result of your screening test. You must isolate until you get a negative result from the Health Department. Self-isolation after the positive test or if you have COVID-19 symptoms can help break chains of transmission and limit the spread of COVID-19. It is not acceptable to just repeat the rapid antigen test, hoping for a negative result. Any positive results need follow up with a PCR test, it is important that you receive timely medical advice.
What if I get a negative test result?
You must continue to follow the latest health advice and restriction of the state that you reside in. If you develop any symptoms, you must immediately get a standard COVID-19 test and isolate until you get a negative result from the state health department.
What if I have symptoms of COVID-19?
Rapid antigen testing is not appropriate if you have any symptoms of COVID-19. You will need to get a standard COVID-19 test (PCR) at a COVID-19 testing clinic and isolate, until you receive a negative result.
Please note that different states and territories may have differing testing requirements, based on their public health orders.
It is important that you follow the rapid antigen test instructions this will ensure that you do not get false negatives and false positive results, minimise spread of infection and the correct way for sample collection to avoid physical damage. This will also ensure the proper and safe disposal of samples and used tests.
Reference
https://www.tga.gov.au/qas-conditions-supply-rapid-antigen-tests