A new test for COVID promises an alternative to rapid antigen tests

A new type of COVID test should be available from November for Australians to use at home.

It promises an alternative to rapid antigen tests (RATs) that we are familiar with. It also promises a faster and more convenient option than PCR (polymerase chain reaction) tests carried out in the laboratory.

The distributor sells the new product as “a portable PCR self-test kit“and”a game changer” in detecting COVID.

But does this new set deliver what it promises? And is it worth the price? Here’s what we know from the limited public data.

What is this new test?

The new test is this EasyNAT COVID-19 RNA Testwhich received for delivery to Australia.

This is a variety nucleic acid test. This makes it somewhat similar to laboratory PCR tests, which also detect the genetic material of SARS-CoV-2, the virus that causes COVID.

But laboratory PCR tests amplify the genetic material in a different way to this home test. So, strictly speaking, this new test is not a PCR test.

The a new test not a RAT either. The rats work by testing for viral antigens (the parts of viral proteins that create an antibody response).

But the test uses a collection technique you’re already familiar with – a nasal swab.

How does it work?

What’s new (to the general public) is the technology behind the test and its use to detect COVID at home.

It uses a process called isothermal cross-strengthening of the primer to copy a small amount of viral RNA extracted from a nasal swab. He does this many, many times so that there is enough viral RNA for the test to detect.

It does this without multiple cycles of high and lower temperatures used to copy and amplify viral RNA in laboratory PCR testing.

Medical professionals are already using this technology (and the better known PCR). detect COVID in hospitals and other healthcare institutions. We know them as “point-of-care tests” because they can provide quick results at the bedside, rather than a swab that needs to be processed in a lab.

EasyNAT takes it further because it can be done at home. The test is said to detect all current variants of SARS-CoV-2.

For comparison, there are tests is currently underway to find out how effective the RATs available in Australia are at detecting variant omicron.

Am I doing the test like a RAT?

Unlike the RAT, this test must be refrigerated before use.

You take a swab from your nose, insert it into the solution in the tube, then add one drop to a special battery operated cassette.

You then add the buffer solution to the cassette, replace the cap, turn on the sample processing cassette and wait 55 minutes. After switching off the cassette, add the second batch of buffer solution, close the cap and wait another 5 minutes before reading the result. The result should be read within 30 minutes of completing the test.

So it takes an hour to get results—much faster than waiting for results from a lab-processed PCR test, but much longer than RAT, where you get results in about 15 minutes.

Does it work?

The Therapeutic Goods Administration (TGA) describes the test as “very high sensitivity“. This means over 95% positive match with the lab PCR test. This is comparable to the most sensitive RATs. But it is more sensitive than some RATs on the market (labeled “acceptable sensitivity” that match the lab). PCR tests in more than 80% of cases).

The manufacturer reports a percentage positive agreement with PCR 95.4%.

Regulatory bodies in the European Union and Australia have approved the test for COVID.

The manufacturer also reports the figure in 99% accuracy compared to laboratory PCR tests. This is a reflection of sensitivity (correctly detecting a positive case) and specificity (not giving a false positive result). EasyNAT has a sensitivity of 95.4% and a specificity of 99.8%.

In comparison, depending on the brand, RATs have sensitivity more than 80% to more than 95% and specifics at least 98% to 100%.

What are the disadvantages?

Testing errors (e.g. incorrect swabbing technique, incorrect storage) mean that potential errors with home RAT are just as likely with EasyNAT.

A company spokesperson says the test is expected to retail for around AU$55, which is significantly more expensive than the RAT (a single test retails for US$9-10 or are free for some people).

It is not yet clear whether a positive result for COVID with this test is enough for eligible people to receive oral antiviral drugs for COVID, such as Paxlovid or Lagevrio, under the Pharmaceutical Benefits Program.

Current requirements to have someone’s COVID status confirmed by a PCR test or a “medically verified” RAT (supervised by a healthcare professional).

In two words

EasyNAT is more expensive than RAT and takes longer to run. Overall, it doesn’t seem more sensitive or specific compared to the best “very high sensitivity” RAT. But it is more sensitive than some RATs on the market.

I would like to know if this test can detect COVID earlier after infection compared to RAT (it usually takes at least a couple of days after infection before enough viral proteins accumulate to detect on RAT). This data is not publicly available.

This article is reprinted from Conversation under a Creative Commons license. To read original article.