What is an antigen?
According to Harvard’s Medical Dictionary of Health Terms, an antigen is any substance that the body recognizes as harmful or foreign, which induces the immune system to produce antibodies against it1.
How do antigen tests identify COVID-19?
Rapid antigen tests identify protein fragments on the surface of the coronavirus to identify the presence of the pathogen amongst people doing the test2. Samples are taken from subjects by swabbing inside the nose or mouth.
How are antigen tests administered?
Rapid antigen tests are commonly administered by using a sterile cotton swab and taking samples from the nasal cavity or mouth and adding a liquid solution to get a result.
Here is a short breakdown of the procedure:
- Collect the sample by swabbing and rotating the cotton swab inside both nostril
- Place the swab inside the testing well
- Add the liquid testing solution
- Wait for 15 minutes to get a result
Read the full step-by-step guide on how to administer the 20test rapid antigen test.
How accurate or reliable are antigen tests?
The accuracy and reliability of rapid antigen tests is often debated. Compared to polymerase chain reaction (PCR) tests, rapid antigen tests are slightly less accurate.
Generally, test accuracy is measured using sensitivity and specificity.
- Sensitivity is defined as the ability to correctly identify subjects with COVID-19.
- Specificity is defined as the ability to correctly identify subjects without COVID-19.
PCR tests have been shown to be up to 100% accurate, although accuracy varies depending on which test is used. Some tests have been found to present false-negative result rates of 15% to 20%3.
In comparison, rapid antigen tests have been found to show false-negative rates of up to 20%4. 20test’s rapid antigen test kit accurately identifies 92% of people who do have COVID-19, and correctly identifies 99.67% of people without COVID-19.
Just to clarify, a false negative is when a subject is incorrectly diagnosed as not diseased. For example, let’s say that someone has COVID-19 and takes a test, if the test result returns a negative result, despite actually currently being infected, this would be considered a false negative result. The test did not correctly identify someone with the coronavirus.
What are antigen tests used for?
Rapid antigen tests are used to identify people that currently have the virus5. Past infections can be identified using other types of tests.
Other than for identifying COVID-19, antigen tests are commonly used to identify:
- Streptococcus infections
- the influenza virus
- Malaria
Where can I get a rapid antigen test?
Depending on where you live, rapid antigen test kits can be found in physical stores and buildings like pharmacies, local healthcare services, and facilities.
They can equally be purchased online from a variety of websites. Make sure that you buy your test kit from a reliable and trustworthy website to ensure the accuracy of your test.
Who should do a rapid antigen test?
- People with symptoms
- Household, social, workplace or education contact of a positive case
- Pre-event testing, before visiting vulnerable family members
- A worker, resident, patient, or client in a high-risk setting where there is a current confirmed outbreak
- Before going into hospital for a procedure if this is requested by the hospital.
- International arrivals (passengers and flight crew entering NSW from overseas)
What happens if I get a negative rapid antigen test result?
If you are a household contact or classified as a high risk exposure you need to continue to isolate for 7 days. You must follow the advice for people exposed to COVID-19 to determine your risk. To determine if you are a high risk exposure use the information for people exposed to COVID-19 and follow the relevant isolation advice.
If you have symptoms, please take another rapid antigen test in 24 hours or have a PCR test. If your second test is positive you are considered a confirmed case. If the second test is negative, you should isolate until your symptoms have gone.
If I am a confirmed case what do I do?
You should follow the advice for people testing positive for COVID-19 and self-isolate for 7 days since date of the positive rapid antigen test.
You should register your positive test result as soon as possible by visiting the Service NSW app or website (coming soon). Providing NSW Health with your test result will enable us to connect you to the best care and recovery plan appropriate to you.
What type of rapid antigen tests should I use?
The Australian Government's regulatory agency, the Therapeutic Goods Administration (TGA), oversees the conditions of supply for rapid antigen test kits.
For your own safety you should only use a self-test kit that has been approved by the TGA. The TGA website has a list of all home use tests approved by the TGA, along with a copy of the manufacturer’s instructions for each test.
A consumer fact sheet is available on the TGA website.
More detailed information on rapid antigen self-tests can be found on the TGA website.
How do I use a rapid antigen test kit?
There are different self-test kits available. Follow the instructions provided within the test. Watch a quick video from NSW Health on how to use a basic test.
All tests are for single use only. This means you can only use each test once. Do not use a test more than once or try to use one test on multiple people.
EU health preparedness: A common list of COVID-19 rapid antigen tests; A common standardised set of data to be included in COVID19 test result certificates; and A common list of COVID-19 laboratory based antigenic assays Agreed by the Health Security Committee Common list of COVID-19 rapid antigen tests (Annex I) Agreed by the Health Security Committee on 17 February 2021. First update: 10 May 2021; Second update: 16 June 2021; Third update: 7 July 2021; Fourth update: 14 July 2021; Fifth update: 23 July 2021; Sixth update: 20 October 2021; Seventh update: 10 November 2021; Eight update: 8 December 2021; Ninth update: 21 December 2021. Common standardised data set to be included in COVID-19 test result certificates (Annex II) Agreed by the Health Security Committee on 17 February 2021. An update to Annex II was agreed by the HSC on 19 March 2021 Common list of COVID-19 laboratory based antigenic assays (Annex III) Agreed by the Health Security Committee on 20 October 2021 2 I. Introduction Robust testing strategies are an essential aspect of preparedness and response to the COVID19 pandemic, allowing for early detection of potentially infectious individuals and providing visibility on infection rates and transmission within communities. Moreover, they are a prerequisite to adequate contact tracing to limit the spread through prompt isolation. Also in the context of the circulation of SARS-CoV-2 variants of concern, surge testing in addition to existing testing deployment has proven to be key for controlling and suppressing further spread of the virus. While the reverse transcription real-time polymerase chain reaction (RT-PCR) assay, which is a nucleic acid amplification test (NAAT), remains the ‘gold standard’ for COVID-19 diagnosis, rapid antigen tests, which detect the presence of viral proteins (antigens), are increasingly being used by Member States as a way of further strengthening countries’ overall testing capacity, particularly in case of limited NAAT capacities or where prolonged testing turnaround times results in no clinical utility. The Health Security Committee (HSC) agreed on 17 September 2020 on Recommendations for a common EU testing approach for COVID-191 , setting out various actions for consideration by countries when updating or adapting their testing strategies. The Recommendations included Member States’ first experiences with rapid antigen tests and their deliberations concerning the settings and situations in which these tests should be used. Since then, the HSC has been discussing the use and application of rapid antigen tests in great depth, and has brought together a wealth of (technical) information on the types of tests used in European countries and the conditions applied. On 21 January 2021, Member States unanimously agreed on a Council Recommendation setting a common framework for the use of rapid antigen tests and the mutual recognition of COVID-19 test results across the EU2 . The Council Recommendation called on Member States to agree on three concrete deliverables: 1. A common list of COVID-19 rapid antigen tests that are considered appropriate for use in the context of the situations described in the Council Recommendation, that are in line with countries’ testing strategies. 2. A selection of rapid antigen tests of which Member States will mutually recognise the test results for public health measures. 3. A common standardised set of data to be included in COVID-19 test result certificates, further facilitating the mutual recognition of COVID-19 test results. Based on the information collected by the HSC, and taking into consideration the current epidemiological situation and the testing strategies and approaches that have been put in place across the EU, this document sets out the deliverables as agreed by Member States. 1 https://ec.europa.eu/health/sites/health/files/preparedness_response/docs/common_testingapproach_covid-19_en.pdf 2 https://data.consilium.europa.eu/doc/document/ST-5451-2021-INIT/en/pdf 3 This document is based on the content of the Council Recommendation and further criteria agreed by Member States, and considers the relevant recommendations published by the Commission3 as well as the updated technical report issued the European Centre for Disease Prevention and Control (ECDC)4 and the World Health Organization (WHO)5 . II. Annex I: Common list of rapid antigen tests Point 11 of the Council Recommendation of 21 January 2021, calls on Member States to, without prejudice to Directive 98/79/EC, agree on and maintain a common and updated list of COVID-19 rapid antigen tests that are considered appropriate for use in the context of the situations described under point 6 and are in line with countries’ testing strategies. This list should be shared with ECDC and the Commission to prevent duplication of work and to feed into ongoing initiatives, particularly the “COVID-19 In Vitro Diagnostic Devices and Test Methods Database6 , hosted by the Joint Research Centre (JRC). Annex I to this document sets out a common list of rapid antigen tests. This list has been incorporated by the JRC in its COVID-19 In Vitro Diagnostic Devices and Test Methods Database. The common list of rapid antigen tests is regularly being reviewed by Member States, and, if necessary, be updated in line with new results from independent validation studies becoming available and new tests entering the markets. These updates are also taking into account how mutations of the SARS-CoV-2 virus may affect the efficacy of rapid antigen tests, allowing for the removal of tests no longer deemed effective. The effect of SARS-CoV-2 mutations on the efficacy of NAAT, in particular RT-PCR assays, will also be kept under review. A first update to Annex I was agreed by the Health Security Committee on 10 May 2021, a second update on 16 June 2021, a third update on 7 July 2021, a fourth update on 14 July 2021, a fifth update on 23 July 2021, a sixth update on 20 October 2021, a seventh update on 10 November 2021, an eight update on 8 December 2021, and a ninth update on 21 December 2021. As stipulated in point 15 of the Council Recommendation of 21 January 2021, Member States will agree on a selection of rapid antigen tests of which they will mutually recognise the test results for public health measures. The HSC agrees that, considering that all of the rapid antigen tests included in the EU common list are eligible for a test certificate issued as part of the EU Digital COVID Certificate7 , the entire list is considered to consist of rapid antigen tests of which Member States mutually recognise the test results for public health measures.
