While PCR tests are still available and remain the “gold standard” for testing, many have turned to rapid antigen tests (RATs) out of convenience or as part of a requirement to return to work or school.
They can provide results within minutes, don’t require a healthcare worker or lab to process, and help to catch COVID-19 cases that otherwise would have gone undetected.
But with these benefits comes a range of limitations – the biggest one being that they can provide false negative or false positive results.
Recently, some doctors have warned people against relying on a negative RAT result.
Meanwhile, the makers of RATs have hit back, blaming false negatives on a lack of education about how and when to properly use the tests.
So is there any evidence that indicates the effectiveness of RATs has been impacted? And does it have to do with people using them incorrectly?
Australia faces ‘an education gap’ that was ‘never filled’ after RATs went on the market
Pathology Technology Australia, the peak body for test manufacturers and suppliers, defended the performance of rapid tests against new variants of Omicron, accusing critics of “fearmongering”.
“Nothing has changed, we’re yet to see any evidence that clearly indicates performance has been impacted by the subvariants,” chief executive and clinical biochemist Dean Whiting said in a statement.
“There is an education gap in Australia that was never filled after RATs became available.”
“I think a lot of the false negative results are due to incorrectly collecting the sample,” Mr Whiting said.
Here are the essentials to taking a RAT.
Store the test at 2C-30C
The Therapeutic Goods Administration (TGA) warns that tests “may not work properly” if they have been exposed to excessive light or heat, or if the packaging is damaged.
The instructions for a RAT specifically say to store it in a cool, dry place at 2 degrees Celsius up to 30C.
Do not freeze the kit and do not store it in direct sunlight.
Check the expiration date
According to the TGA, RATs can be stored for 12 months from the date of manufacture.
Do not use the test after its expiration date.
Blow your nose
David Speers, a clinical microbiologist and head of the microbiology department at PathWest, told ABC Radio Perth this will clear any excess mucous so that it won’t interfere with the results.
“What you want to do is sample the lining of the nose — you’re not sampling the secretions as such,” he said.
Only open the kit right before use
If you open the kit components, don’t suddenly delay taking the test and leave it out until you decide to.
When you open the kit, take the test straight away.
Don’t contaminate the test
Whether it’s with your fingers or your kitchen tiles after dropping it (there’s no five-second rule here), the tip of the swab should not touch anything.
So make sure it doesn’t come into contact with any other surfaces.
Swabbing at the wrong angle and depth
You’ve made it to the hardest part.
It’s easy for many to get the angle or depth wrong when it comes to swabbing.
Mr Whiting said he has seen many people wave the swab around the inside of their nostrils when taking a RAT.
“This is not the way the manufacturer intended for you to use the test,” he said.
“The manufacturer intended you to put the swab at least 1.5cm up your nose and swish it around five times, then do the other side.”
A guide published by the Public Health Laboratory Network (PHLN) and the Department of Health says to insert the swab tip 2cm to 3cm into each nostril.
The key is to insert the swab all the way up your nostril until you feel it rub against the back of your nose.
Rather than going directly upwards with the swab, make sure the swab passes horizontally.
Then rotate the swab gently against the walls of the nasal passage five times, for 15 seconds in each nostril.
“You will know when you’re doing this correctly because it’s slightly uncomfortable,” Mr Whiting said.
“If your eyes aren’t watering or you’re not resisting the urge to sneeze, then you’re not taking the sample correctly.”
Swirl the swab in the tube for 10 seconds
Hold the solution tube firmly with one hand.
Once you’ve inserted the swab into the tube, swirl it around in the fluid for 10 seconds.
Then pinch the swab tip through the tube to remove any remaining fluid.
For some testing kits, you will need to snap the end of the swab. The swab will indicate where to do this.
Don’t add too many drops to the device
Remove the test device from its protective package and place it on a well-lit, flat surface.
Keep the tube vertical with the cap pointed down.
Squeeze three drops of liquid from the tube into the well on the device.
Some tests say two drops, while others may say four. Make sure you follow the instructions of the manufacturer of your test.
Adding too many drops or too few will affect the timeline and the test will be inaccurate.
Follow the no earlier than 15, no later than 20 rule
Keep the test device on a flat surface.
Read the result at 15 minutes.
Do not read it earlier than this, or after 20 minutes.
After 20 minutes, the result might become inaccurate.
Misreading the result
- Two lines mean you have tested positive for COVID
- A line at C only means you have tested negative for COVID
- A line at T but not C means your test is faulty
- No means lines your test is faulty
Dispose of the kit correctly
Make sure you place the swab, tube and test device into the plastic bag provided and seal everything in there.
Then you can dispose of it in the rubbish bin.
As more variants emerge and evolve over the pandemic, many are wondering whether we’re likely to get a variant that can elude testing.
Epidemiologist and biostatistician from the University of South Australia Adrian Esterman said at some point in time, we would likely get a variant that was much harder to detect with existing tests.
But because of Australia’s diverse population and geographical spread, Mr Whiting believes RATs are going to remain highly useful, especially in rural and remote areas.
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