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Dodgy Covid RAT tests

I purchased a box of 5 SARS-CoV-2 rapid antigen tests made by All Test and found that they don’t work. All 5 tests showed I was negative when I was actually positive, as confirmed by a PCR test, a RAT test made by a different manufacturer, and my Covid symptoms. When using the All Test units I carefully followed the instructions, and they were all done on different days during the course of my infection, so they should have showed positive on at least a few days. I reckon the All Test units don’t work.


Welcome to the Community @CMC

The list of approved RAT tests and their tested accuracy is listed on the TGA site.

You should report your experience to the TGA with full documentation of the All Test product, batch number and batch dates, dates of each respective test as well as similar details of the other RAT tests you used accompanied by your PCR result.

It could be a bad batch. The TGA needs reports of real or suspected anomalies to do their job.


Some things to note and useful information for the TGA will be when you used the tests and when did you take the test from the different manufacturer. This information may assist the TGA in determining if the tests were faulty or that there are other reasons to explain the anomalies in the results.

Has PCR test also be undertaken to confirm the positive RAT test (as it could be that this test which is showing a false positive result and could be the anomaly)?


The answer was in the OP unless your query was intended to be more complex than the obvious?

Whether the timing of the various tests has anything to do with the potentially false negative vs the apparently confirmed infection remains information in progress.

FWIW a family all had COVID but the lady of the house did not test positive with RATs they bought even though she had all the symptoms and was surrounded by COVID positive family, but did go positive on a PCR. It adds insight into the veracity of testing as being an end all determination.


Apologies, it should have been timing associated with the tests. Sequencing tests and their results will be useful information to the TGA.

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Hi PhilT & phb.
I’ve lodged a detailed report with the TGA, giving all relevant info (dates, batch no, etc). Presumably not much will happen unless they get a few more reports of dodgy batches of RATs, but at least they’re now got one report. I was aware that the timing of the test relative to the start of infection could affect the test result, which is why I did the 5 tests over a week.


RAT tests have an error rate.
The accuracy or reliability varies with the product.

The probability of a false negative is high, approx 20% in the following discussion. IE the test fails to detect Covid in someone who has Covid approx 1 in 5 times.

It’s not mentioned if this is a random event. If it is the odds of someone with a detective level of infection returning 5 negative tests consecutively is 1 in 5x5x5x5x5. IE 1 in 3125, which are not impossible odds given the millions of Aussies who have been RAT tested.
In comparison the probability of a false positive is low.

There are three key concepts to understanding how accurate RATs (or any diagnostic test) are: sensitivity, specificity and pre-test probability.

RAT tests are a quick indicator. The reliability (sensitivity, specificity) are assessed as by the TGA when issuing approval for a particular RAT product. There is a trade off between the lesser reliability accepted at a low relative cost, ease of use and a quick indicator vs an expensive highly reliable PCR test that takes time.

I believe the concern was that there were symptoms leading to suspicion and other branded RAT tests were positive as well as the PCR, and the All Test product was an outlier. Not the statistical odds of a false negative. The timing of each we know little, eg was the All Test negative and another RAT going positive done concurrently? Perhaps just a detail in the saga but an important one. Unless one or more of us are researchers specialising in infectious disease testing or experts in regulatory affairs/approvals in the TGA, the specifics are essentially speculative against our knowledge bases…

Putting the details we know together and the right thing to do was to report it as was done, and good on @CMC for doing so. :wine_glass:


I agree that is what needed to be done.
The ABC’s frequent presentations by Dr Norman Swan included a discussion on the statistical probabilities around RAT testing not giving the correct result. His commentary and those of several other professional variously providing input across the ABC in particular pointed out that the TGA approved RAT tests were far more likely to report false negatives than false positives.

It’s one supposed reason there was an initial reluctance by medical authorities and the Federal Health Minister to include RATs in their control strategies. It’s possible that ‘All Test’ product has a quality issue, and that is for the TGA to assess.

It’s also relevant to point out there may not be an issue with any of the ‘All Test’ product in use by the community, or give cause for a loss of confidence. Note the TGA had approved at least two types of ‘All Test’ kits, one nasal and one oral. Both were well rated by the TGA relative to other brands.

Which Covid rapid antigen tests sold in Australia can you trust and what do they cost? | Australia news | The Guardian

The best thing to do if you have symptoms or other indications and the RATs are returning negative is to as @CMC did visit a clinic for the highly reliable PCR. Of note there are questions around the effectiveness of the most common type of test we are likely familiar with.

I’ve experienced numerous deep nasal swabs, some administered by Doctors and nursing professionals, vs self inflicted sampling. There is a tendency to not be as diligent. The difference in outcomes (various reasons) noted by the Imperial College London is not a surprise.


It appears the ‘trust us’ aspect of the TGA’s approval process has not been met with the explicitly required ‘trust’ in return. Some might consider it is just red tape or administrativia rather than the tests themselves, but when a company ignores its responsibilities to monitor, support, and report nobody really knows.


The saga continues. Who to believe? On one side we have Hough Pharma defending their honour (and profits) and on the other the TGA supposedly defending the rest of us.

"In a statement about Hough Pharma, the TGA said: “In addition to not meeting deadlines for providing information to the TGA, the lack of customer support has been reported by consumers and verified by TGA investigations.”

It appears Hough started well but went missing on the details required over time, all mentioned by TGA in the article.