Considering buying a Rapid Antigen Test to screen for Covid, but unsure which is the most accurate? Here, we reveal the most reliable RAT tests on the market, as approved by the TGA.
Many PCR testing sites are currently at full capacity, so it’s becoming more and more difficult to get tested for Covid. As you know, Omicron cases reached record levels just before Christmas, and as a result we saw thousands of people waiting in enormous queues — sometimes hours long — to receive a negative PCR test ahead of their festive travel plans.
With Covid numbers still on the rise, PCR testing sites are becoming increasingly limited, so RAT tests are fast-becoming the go-to for Covid detection. But with questions surrounding how accurate these tests are compared to PCR tests, plus the added issue of a country-wide shortage, which tests should you invest in that guarantee reliable results? Here’s everything you need to know.
What’s the difference between a PCR and RAT?
Much like a PCR test (polymerase chain reaction test), RATs test for the virus by collecting a sample of mucus or saliva from either the nose or mouth, or in some cases, both. This tests for viral particles present in either the mouth and/or nasal passage.
The main difference between the two, is that PCR tests are carried out at either a drive-though or testing clinic, and take 24 to 48 hours to receive results. PCR swabs are then sent to the laboratory for testing to see if the sample matches the coronavirus’ genetic code — it can pick up the smallest fragment of the virus, even if it’s already dead, making them almost 100 per cent accurate.
This makes PCR tests the most accurate and trusted form of testing — PCRs are considered the "gold standard" of testing with an accuracy rate of above 90 per cent. These tests are currently free under Medicare, unless you need an urgent result (for travel purposes, for example), which you would have to pay for.
Rapid antigen testing kits on the other hand, can be bought over-the-counter at pharmacies for anything between $15 and $30. They can be self-administered at home and take around 10 to 20 minutes to get your results.
Rapid tests test for a specific protein of the virus, which is known as an antigen. The swab (which is taken from inside your nose and/or mouth) reacts to a solution and detects whether or not that particular protein is present.
Any RAT approved for use in Australia must have an accuracy rate of at least 80 per cent (there are varying RATs ranging from 80 to 95 per cent accuracy). Whilst this does makes them less accurate than PCRs, the added benefits of an RAT is the convenience to administer yourself, and the fact that you’ll receive your results much quicker, meaning you don’t have to stand in line for hours waiting for a PCR.
Having said that, it’s worth bearing in mind that RATs can, at times, deliver false negative results — trials around the world have found that rapid tests picked up about 72 per cent of cases with symptoms, but only 58 per cent of those without symptoms — and are less likely to pick up early infections or the tail end of an infection.
A statement from the US Food and Drug Administration (FDA) said, "Antigen tests are generally less sensitive and less likely to pick up very early infections compared to molecular tests,"
"If a person tests negative with an antigen test but is suspected of having COVID-19, such as experiencing symptoms or have a high likelihood of infection due to exposure, follow-up molecular testing is important for determining a COVID-19 infection.”
It’s therefore advised that anyone with a positive RAT should consider themselves COVID-positive, then follow up with a PCR test to confirm that diagnosis.
RATs are, however, very effective at picking up whether you are in the infectious phase — RATs work better on symptomatic people because they are more effective at detecting high viral loads — so it’s a good idea to use RATs before attending any large gatherings or before coming into contact with any vulnerable people.
So which rapid antigen testing kit is the best to buy?
The Therapeutic Goods Administration (TGA) has approved more than 15 different types of RATs in Australia, and categorised them according to their clinical sensitivity — acceptable sensitivity, high sensitivity and very high sensitivity.
These are broken down into percentage of accuracy:
- Acceptable sensitivity — kits with a minimum of 80 per cent accuracy.
- High sensitivity — kits with greater than 90 per cent accuracy.
- Very high sensitivity — kits with greater than 95 per cent accuracy.
Any RAT must achieve minimum clinical sensitivity of at least 80 per cent.
So, the greater the sensitivity of the test, the better the chance it has at detecting COVID-19, and the less chance it will deliver a false negative.
It’s also worth noting that five out of the six very high sensitivity tests are all nasal tests:
- All Test nasal swab
- LYHER nasal swab
- OnSite nasal swab
- Panbio nasal swab
- Rapid nasal swab
The sixth is the V-Chek saliva test.
This is because nasal swabs, on the whole, tend to be more sensitive at detecting the virus in people within seven days of having symptoms — when they are the most infectious — compared to saliva tests alone.
In fact, the very high sensitivity nasal swabs are almost equivalent in terms of sensitivity to a PCR in picking up the virus — as documented in a recent study by the University of California, San Francisco. Researchers at UCSF found that the at-home self-swabs of the front part of the nose were almost as accurate as PCR tests, which makes them incredibly reliable when testing for COVID-19.
Although, in terms of the TGA’s sensitivity scale, both nasal and saliva RATs have been listed as highly accurate in detecting the virus. It perhaps depends on your personal preference — some people find the saliva tests are much easier to administer than the nasal swabs, which tend to be a little uncomfortable for some.
A positive RAT result should still be confirmed with a PCR test. A negative test should be validated with another rapid test a day or so later.
You can view the full list of Australian approved COVID-19 self-tests on the TGA website.
We’ve also outlined our full range of rapid antigen tests, available in store and online. And to make things easier for you, we’ve categorised them according to their clinical sensitivity.
Shop the collection below.
Very High Sensitivity RATs
Cellife COVID-19 Antigen Rapid Test (Nasal Swab) Self-Test
All Test COVID-19 Antigen Rapid Test (Nasal Swab) Self-Test
Lyher COVID-19 Rapid Antigen Test Device (Nasal Swab) Self-Test
High Sensitivity RATs
Testsealabs COVID-19 Antigen Test (Nasal Swab) Self-Test
Orawell COVID-19 Rapid Antigen Saliva Test Device (Self-Test)
RightSign COVID-19 Antigen Rapid Test Cassette (Nasal Swab)
Acceptable Sensitivity RATs
Ecotest COVID-19 Saliva Rapid Antigen Test Pen
InnoScreen TGA Approved Individual Rapid Antigen Test
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