Tests for COVID-19 aim to detect the causative virus, SARS-CoV-2, or an immune response to SARS-CoV-2.
Available evidence on the performance of COVID-19 tests mainly comes from symptomatic patients.
The indications for conducting a COVID-19 test have changed through the course of the pandemic. See the current suspect case definition and the testing criteria on the Department of Health website.
The three main types of SARS-CoV-2 tests are:
- Nucleic acid detection tests - to detect SARS-CoV-2 viral (Ribonucleic acid) RNA;
- Rapid antigen tests - to detect antigen viral proteins from the SARS-CoV-2 virus; and
- Serology tests - to detect IgM and/or IgG antibodies against SARS-CoV-2.
Nucleic acid tests
There are different types of nucleic acid tests that can be used to detect SARS-CoV-2 viral RNA, including reverse transcriptase (RT) polymerase chain reaction (PCR) and isothermal nucleic acid amplification tests (e.g. loop-mediated isothermal amplification (LAMP) tests). PCR tests are generally considered better at detecting the presence of the SARS-CoV-2 virus and are currently the gold standard for diagnosis of COVID-19.
PCR assays typically take several hours (including specimen processing time) to generate results and require complex laboratory equipment and trained technicians. There are now some near patient SARS-CoV-2 PCR instruments available that can be used outside of a laboratory. These systems can provide quicker results but cannot do as many tests at once.
The Peter Doherty Institute for Infection and Immunity has completed a validation study of the Beijing Genomics Institute SARS-CoV-2 Real time PCR test kit and associated instrumentation and reagents.
Rapid antigen tests for viral protein
Rapid antigen tests intended for use at the point-of-care detect the presence of viral protein from SARS-CoV-2 and may be used in the diagnosis of a SARS-CoV-2 infection in a symptomatic patient. COVID-19 antigen tests are generally intended for use with nasopharyngeal, throat or nasal swabs or saliva and testing should be performed in accordance with the manufacturer's instructions for use.
While rapid antigen tests can provide a result within 15-30 minutes, they are generally considered to be less sensitive than a PCR test which is still currently the gold-standard in SARS-CoV-2 diagnosis.
Rapid antigen tests are best performed within the early stages of acute infection, when viral load is at its highest levels (i.e. within the first 5-7 days from symptom onset), after which antigen levels may drop significantly. A symptomatic patient with a negative rapid antigen test result should be advised to have a PCR test. The rapid antigen tests are not as reliable when used to screen asymptomatic persons and can generate false negative or false positive results particularly in low prevalence disease settings.
Different state and territory jurisdictions may have differing testing and reporting requirements based on their public health orders. The responsibility for reporting positive test results to state and territory health departments typically rests with the individual being tested. The relevant state or territory government websites provide more information on whether reporting of positive test results is required and how individuals can report them.
Rapid antigen point of care tests
Rapid antigen point of care tests are tests that can be performed by health practitioners, or trained persons under their supervision. This ensures a suitable health practitioner, or trained person under their supervision is available to ensure an adequate sample is collected, correct interpretation of results and they can provide immediate clinical advice if required.
For more information see COVID-19 Point-of-Care tests.
Rapid antigen self-tests (home use tests)
These are tests that can be used unsupervised at home without the involvement of a health practitioner. The person collects the sample, performs the test, and interprets the results by themselves.
For more information see COVID-19 rapid antigen self-tests.
Serology antibody tests
The TGA has approved a number of laboratory-based serology immunoassay tests and point-of-care serology tests that utilise lateral flow immunoassay technology.
Point-of-care serology tests are intended to detect IgG and/or IgM antibodies to SARS-CoV-2 from venous or finger prick blood samples that are placed on a test strip. These tests look similar to common pregnancy tests. Results take about 15–30 minutes.
There is a window period between virus infection and the production of IgM and IgG antibodies, and the sensitivity and specificity of IgM/IgG antibody tests early in SARS-CoV-2 infection is not well characterised. Antibodies can take up to two weeks or more to become detectable after infection with SARS-CoV-2. Because antibody tests do not detect active viral shedding, they cannot detect if an individual is infectious. Though they provide some useful information when combined with the clinical picture, a suggestive clinical picture plus a positive point-of-care may be considered sufficient for a presumptive positive diagnosis and subsequent management.
Human coronaviruses circulate frequently every year and cause a common cold type illness. Cross reaction with antibodies formed by current and past exposure to seasonal human coronavirus infections can cause false-positive results. Serology tests can also fail to detect COVID-19 if testing is performed in the acute phase of the infection prior to the development of detectable antibodies.
Serology antibody assays generally provide historic information about viral exposure. They can indicate whether an individual has past exposure to SARS-CoV-2. It is not yet evident that the detection of antibodies reflects the presence of protective immunity, so the detection of antibodies may not exclude remaining infectivity in a patient.
For more information see COVID-19 serology point-of-care tests.
COVID-19 test performance
The TGA continues to prioritise applications for COVID-19 tests taking into consideration the analytical and clinical performance data available at the time of application. All SARS-CoV-2 tests currently approved for supply are required to provide updated evidence to support the ongoing safety and performance of the tests to the TGA.
The TGA is conducting post-market review of all approved COVID-19 serology and rapid antigen point-of-care tests and rapid antigen self-tests to verify their performance and inform their best use. The Department of Health has engaged the Peter Doherty Institute to assist in the post-market validation of these tests.
The TGA will take action in relation to any report of poor or faulty performance of these devices. Reports can be submitted via the TGA website.
How to report an adverse event/problem with a medical device
An adverse event or problem with a medical device can be reported online at Report a problem or side effect.
If you require assistance to report a medical device problem, call 1800 809 361 (08:30 am to 5:00 pm, Monday to Friday) or email IRIS@health.gov.au.
For more information please contact us at COVIDtests@tga.gov.au or 1800 141 144.