Rapid antigen tests explained: What you need to know about at-home Covid tests

Australians can get rapid Covid tests from supermarkets, chemists and petrol stations now. Join our experts for a live chat to see how they work.

Australians will be able to tell whether they have Covid within 15 minutes from Monday when nine rapid antigen tests go on sale in supermarkets, pharmacies and even petrol stations.

The self-administered rapid tests are similar to off-the-shelf pregnancy tests and will cost between $8.50 and $15 per test. There is no Medicare rebate.

Here we explore some of the key questions surrounding their ease of use and validity.

Sue Dunlevy, News Corp’s National Health Editor host a live chat with Allison Rossiter, Managing Director of Roche Diagnostics Australia whose company makes the kits at pharmacies, with Dr Lynette Waring, the chair of the Royal College Pathologist Australasia’ s microbiology advisory committee.

Watch it above or on Facebook.

HOW ACCURATE ARE RAPID TESTS?

The rapid tests aren’t as accurate as PCR tests, and if a person tests positive they will need to have a regular PCR test to confirm the diagnosis.

The tests are likely to miss a small number of Covid cases and some people will get a false positive result indicating they have Covid when they do not.

Allison Rossiter, the managing director of Roche Diagnostics which makes one of the rapid tests, said this was why it was important to have a follow up PCR test if there was a positive result.

“You should always double check it and also I would recommend, if you feel absolutely dreadful, and it’s come up as a negative, but you think I still I’m not right, go and get a PCR always double check it,” she said.

WHEN DO THE TESTS WORK BEST?

The tests work best in the first week of a Covid infection and can pick up the virus even if you are asymptomatic.

Some people will get a false positive result indicating they have Covid when they do not. .

HOW DO YOU PERFORM THE TESTS?

The good news is most of the tests do not require an eye watering, brain tickling deep swab off the back of the nasal cavity and some work using saliva instead.

“You put the swab a couple of centimetres into the nostril, and you kind of sweep it around the nostril about four times, a tiny little brush, so there’s no more making your eyes water,” Ms Rossiter said.

The swab is then put into a buffer solution that takes any virus found in the nostril, off the brush and into the solution.

A small amount of this solution is then squeezed into the window of the test cassette.

“You squeeze a bit of that onto the to the window, and then within 15 minutes, you’ll get your results and it gives you two lines just like a pregnancy test to say whether it’s worked and then whether you’re positive or negative,” she said.

Two lines means you are positive, one line means the test is negative.

HOW MUCH DO THE TESTS COST?

The Roche test will be sold in pharmacies and cost around $60 for a pack of five, or $12 per test, bulk packs of rapid antigen tests are being sold online for around $80.

Rapid antigen tests generally cost around $8-$15 per test but many are sold in multi packs containing around 5 tests. Prices can go as high as $80 so consumers are being advised to shop around to get the best price.

SHOULD I BUY THE TESTS OVER THE INTERNET?

There are many brands of rapid antigen tests but only nine have been approved by the TGA for self use in Australia. If you are buying over the internet please check the TGA website to make sure the test is one of the brands approved by the TGA. You can check the list of approved tests here.

ARE THERE TESTS THAT DON’T REQUIRE YOU TO PUT A SWAB UP YOU NOSE?

The My Covid tests, made by AM Diagnostics, and the Ecotest, made by Emergence Technology, do not require a nasal swab. Instead you spit saliva into a test tube, or place a test tube under your tongue, add a buffer then squeeze this onto the test cassette and get a result in 15 minutes.

Some tests use saliva to detect Covid. (Photo by Phil Walter/Getty Images)

HOW MANY TESTS ARE AVAILABLE?

The TGA has approved nine self administered rapid antigen tests including six Chinese-made tests sold by AM Diagnostics (three tests), Medsupply, Hough Pharma and Emergence Technology.

Also approved are a test manufactured in the US by Pantronic, a German-made test sold by Abbott Rapid Diagnostics and the Roche test, manufactured in the Republic of Korea.

What does the medical regulator say about the tests?

“They can’t claim to be diagnostic, you know, because it’s a screening test and people who test positive should go and have a PCR gold standard test,” TGA boss Professor John Skerritt said.

WHEN WOULD YOU USE THIS TYPE OF TEST?

The rapid tests will be useful for people who want peace of mind before visiting elderly relatives, are worried their children may have been infected at school or childcare or want to be sure they are not infectious before attending weddings, funerals or large events, Ms Rossiter said.

“Especially with Christmas coming up and people wanting to be together or travelling and crossing the border,” she said.

SHOULD YOU RELY ON THE TESTS AS A FINAL DIAGNOSIS?

President of the Royal College of Pathologists of Australasia (RCPA) Dr Michael Dray has said rapid antigen tests are less able to detect SARS-CoV-2 and “therefore should never be used alone for diagnostic purposes in a symptomatic patient where a false-negative result may provide unwarranted reassurance and lead to ongoing community transmission”.

SHOULD YOU REPORT THE TEST RESULT IF IT IS POSITIVE?

The RCPA said it was vital that positive and negative results were reported to public health authorities.

Ms Rossiter said there was no way of forcing people to notify authorities if they recorded a positive test.

“This is where I guess the trust has got to come in, I think it’s about Education Trust,” she said.

Authorities need to know who’s got Covid so they can have them isolate and manage outbreaks, she said.

“We educate people to it’s nothing to be ashamed about or embarrassed about, we’re trying to help you so that the health services are there at the right time and make sure that you’re that you’re going to get through the virus and you’re going to come out the other end and be okay,” she said.

Originally published as Rapid antigen tests explained: What you need to know about at-home Covid tests