Rapid antigen tests are here to stay: here’s what you should know.
Since this story was first published in the print edition, I’ve had to update it twice before it went online. Unfortunately, when it comes to the Australian government’s policies on RATs, they’ve been clear as mud so far. What we do know is that they’re a very useful tool for people self-managing Covid risk and exposure.
RATs take roughly 20 minutes from unsealing the packet to delivering a result, and so offer both prophylactic reassurance for those about to go out and mix with large groups or people, as well as diagnostic value for people who may have been exposed to Covid (which is most of us right now).
When they are available at low prices (or free as in the UK), they can be used widely and regularly as part of a person or business’s Covid-combatting kit.
Not all tests have the same accuracy or ease of use. The TGA lists all the self-test kits currently approved for use in Australia at this link.
These tests have been rated according to their PPA levels: the positive per cent agreement, which is the percentage of positives detected by the RAT compared to a ‘gold-standard’ PCR test on the same cases. There are three categories:
Acceptable sensitivity: clinical sensitivity greater than 80% PPA
High sensitivity: clinical sensitivity greater than 90% PPA
Very high sensitivity: clinical sensitivity greater than 95% PPA
Check out the TGA list for how each brand of test is rated. While there is a substantial difference between 80% and 95%, this is per test. Ideally, RATs would be used regularly and multiple negatives or positives, even on the lowest-rated tests, are highly likely to be accurate.
Taxing and testing
Businesses supplying RATs for workplace health and safety are able to claim them as a tax-deductible expense. On 5 Feb, Treasurer Frydenberg announced they would also be exempt from the Fringe Benefit Tax for businesses when they are purchased for work-related purposes. He said the legislation supporting this would be backdated to 1 July 2021.
Individuals purchasing RATs for workplace use will now also able to claim them on tax. This includes workers who do tests before heading in for their shifts. So dig out your receipts from RATs already purchased before you do your next return.
The actual tests are easy for most people to use. Each comes with detailed instructions, which are also available as PDF links at www.tga.gov.au/covid-19-rapid-antigen-self-tests-are-approved-australia if you would like to check before you buy.
In general, a sample is collected from your nose or mouth via swabs or spit and then added to a reagent before being applied to a testing strip. There is some evidence to suggest nasal swabs are more accurate for Delta and saliva/oral tests are better for Omicron.
In some kits, the sample collector, reagent and testing strip are all-in-one. There is a development period for the test, usually 10-15 minutes, then the test can be read (some require UV light, which is supplied).
Each test has two positions for a possible line to develop, one marked C, one marked T. The C is the control line and will tell you that your test is effective. If there is no C line, the test is invalid and should be retaken. Showing ONLY a C line indicates a negative test. T is the test line: a weak or strong T line indicates a positive test and you should follow this up with whatever health directives are in place in your state around further testing, medical contacts or reporting. Some also have an S marked where the sample is added.
Above: The basic responses on a RAT. Note that a positive line may be faint, which is still positive. (Image M. Patthawee/Shutterstock)
For people with limited hand dexterity, look for all-in-one tests like the Orawell or Ecotest, or tests that come with stands or boxes adapted for holding specimen collection tubes. Oral/saliva tests are generally easier to manage.
Do follow the instructions closely, including hand washing. The TGA has also advised people not to eat, drink, smoke/vape, brushing their teeth or chew gum for up to 30 minutes before testing for the most correct result.
Many tests require you to check the results within a specific time window for greatest accuracy, which may be as short as five minutes after the development period. Make sure that you have a timer set and won’t be interrupted through this period.
Since writing the magazine version of this story, accessibility to RATs has improved slightly and prices have stabilised a bit. Fingers crossed, these trends keep going in the right direction and those people eligible for free RATs can start accessing them easily. And also that pharmacy staff across the country have all been given big boxes of chocs by their employers as thanks for getting through this wild time.
