Covid-19 home tests: Know your result in minutes

Rapid Covid-19 test kits are now available, allowing Aussies to test for the illness at home and get a result in 15 to 20 minutes. So, how do the tests work and how accurate are they?

In what is being hailed as a game-changer in the fight against Covid-19, Australians in all but two states are now able to test themselves using rapid antigen test kits.

The tests can be purchased from pharmacies, supermarkets and other retailers, both instore and online.

It comes after Health Minister Greg Hunt announced the Therapeutic Goods Administration (TGA) has approved the use of approved at-home testing kits from November 1.

Previously, only health professionals were able to administer them.

Here’s what you need to know.

What is a Covid-19 rapid antigen test?

As the name suggests, rapid antigen tests are a quick and easy way to test for ‘antigens’, a term used for any foreign substance such as bacteria or a virus.

Covid-19 rapid antigen tests are already widely used in Europe and the United States.

In Australia the tests have been used in aged care facilities, hospitals and workplaces such as fly-in fly-out mining sites and television production sets.

How do the testing kits work?

The kits work a little like a home pregnancy test, in that you add a bodily sample, such as saliva or a nasal swab, into a chemical solution, which then uses a colour or a marker to say whether the coronavirus is present.

Results can be known within 15-20 minutes says Covid-19 Primary Care Response First Assistant Secretary, Dr Lucas de Toca.

“Unlike the standard laboratory test, the PCR or polymerase chain reaction test, it doesn’t look for the genetic material of the virus, but (rather) it looks for a number of key components of the virus,” Dr de Toca says.

If specific proteins are present in detectable quantities, the test returns a positive result.

The TGA says nine antigen tests had been approved so far for self-testing or home use and any rapid antigen tests approved for at-home use would come with simple-to-use instructions, fact sheets and a supporting phone helpline or explainer video.

How accurate are rapid antigen tests?

Until now most people in Australia have been diagnosed with a PCR test, usually administered by a doctor or nurse, which involves taking a swab of the nose and throat.

PCR testing is considered the ‘gold standard’ as it provides more accurate results and can diagnose Covid-19 even in the early stages of the virus.

The downside is the sample needs to be sent to a laboratory, taking between several hours to a couple of days to get a result.

Rapid antigen tests are quick, convenient, and don’t need a lab.

World Health Organisation advisor and University of NSW Epidemiology Professor Mary-Louise McLaws says some tests are “close to 100 per cent” accurate in identifying a person as not having Covid-19 at the time of the test.

“They’re relatively cheap and they do have very good accuracy, particularly when you use them over several days in a row,” Prof McLaws says.

“In Australia it’s best not to use them as a diagnostic test, but as a screening test to determine when you are negative.”

What should I do if I test positive from a home Covid-19 test?

Any positive test needs to be followed up with a PCR test, Prof McLaws says.

“Don’t get anxious if you test positive; go straight away and have a confirmatory PCR test at your GP or at the closest test site,” she says.

The TGA recommends staying home while waiting for your PCR test result (contact your state or territory health department to find about quarantine requirements).

Where can I buy a rapid Covid-19 test kit?

TGA head Professor John Skerritt says there are no constraints on where the tests can be sold, including online and at petrol stations.

“It is a screening test and people who test positive should go and have a PCR gold-standard test,” he says.

Chemist Warehouse is selling the two-pack Right Sign Covid-19 Antigen Rapid Test Kit in stores and online and will shortly have a five-pack variant available nationally.

At this stage South Australia and Western Australia don’t allow the use of rapid antigen tests at home to detect or diagnose Covid-19.

How much does a rapid home Covid-19 test cost?

Rapid home antigen tests cost roughly $30 for a packet of two, and between $50 and $100 for five, depending on the retailer and brand.

They’re not covered by Medicare and have a shelf life of about two years.

Can home Covid-19 tests be used for kids?

Tests on children should always be supervised by an adult.

Check the instructions on your particular home test to see if there are any specific guidelines for using with kids.

If you have any further questions about Covid-19 home test kits, check the TGA fact sheet.

Always read the label. Follow directions for use. 

Written by Liz McGrath.