Australia's anti-antigen insanity #

Update [28 Sept]: At-home testing planned to be available by end of year. The delay was apparently deliberate.


Australia still does not allow rapid antigen testing for home use. This seems ridiculous to me, that we have basically ignored a valuable tool in helping detect and prevent outbreaks.

Some quotes from the TGA FAQ on Antigen Tests.

There is also a potential risk that some individuals could be motivated to conceal or not report a positive test, especially if they felt that their symptoms were mild and, for example they might lose employment income, be unable to go on holiday, or miss an important family event.

This seems absurd to me. Ignoring non-compliant people (who are unlikely to get PCR tested anyway!), you are missing out of tests for asymptomatic and mild-symptom people. People with mild symptoms aren't going to go wait 2 hours in a queue for a PCR test either, convincing them to have a quick test at home seems like an easier ask..

The "be unable go on holiday, or miss an important family event" bit also seems to disregard millions of people being restricted to their homes for months at a time.

Although these tests can detect the virus in the acute phase of infection from symptomatic patients, in community settings where there are low rates of COVID-19 there is a high risk of false positive and false negative results and therefore the results can be susceptible to misinterpretation.

Every positive test is indeed very significant, but so is every positive case! Antigen tests are less accurate in asymptomatic people, around ~60% for a single test. But since the current advice is get tested when you have symptoms, our current detection rate of asymptomatic cases is closer to 0%! So false negatives are still likely to be less frequent that what we get.

And for false positives - if you test positive with rapid test, then you go get a PCR test to verify. This gives you confirmation, and more data on the accuracy of antigen tests (lack of data being yet another reason given for not having rolled them out).

Even the lower bound on asymptomatic cases suggest 15%, and you then have a 3-5 day lag period of them infecting people!

This risk increases with inadequate sample collection.

This seems like a more compelling argument. People may not wash their hands before the test, or get too much mucus on their sample or other things to decrease accuracy. But again, false positives are pretty cheap when the entire state is in lockdown - most people are basically isolating already.

Work is being progressed that may allow the provision of self-tests for COVID-19 in the future. Any change to the current prohibition on the supply of self or 'home' tests will require regulatory change. The timing of introduction of self-testing is critically dependent on achieving specific higher vaccination rates as outlined in the National Plan to Australia's COVID-19 response, and for the states and territories having established systems for reporting positive self-test results and directing individuals to have immediate PCR confirmatory tests.

This is a particularly ridiculous reason. "It will require regulatory change oh no this could take years". The government is somehow able to rush through sweeping surveillance changes virtually overnight, can extend the maximum length of a state of emergency as needed, lockdowns and travel bans can come into effect the same damn day. But allowing people to self-administer a test used in dozens of other countries in the world? I imagine this will need several decades and many committees.

As for needing to "establish systems for reporting positive self-test results". Here you go: "if you self-test positive, get a PCR test immediately to confirm the result".

Use of the test by untrained persons and testing performed outside the supervision of a health practitioner would mean that the person or organisation could be liable if something goes wrong with the performance or interpretation of the test.

Surely irrelevant for self-testing? Are health practitioners liable for the interpretation of PCR tests?If I get a negative test result but am symptomatic the next day can I sue? "Surely you should have known, doctor!". Has this been a concern anywhere in the world yet? If so, add a clause about liability while you are changing the law around approval.

How could we use rapid tests? #

Combined with wastewater testing, as a screening test #

Wastewater testing is a useful indicator, but can't really be narrowed down. Currently it is reported and then you get the same advice as anyone else - "if you have symptoms go get tested". It could be used for targeting areas to mass-deploy antigen tests as a screening tool. As someone that's lived in what is basically a permanent hotspot, either a local pickup spot or tests in my mailbox would be a welcome addition to the neighbourhood.

More regular testing of people in isolation #

Tests every 3 days rather than every two weeks could hugely reduce contact tracing lag! Currently there are tests on Day 1 and Day 13, then 12 days of "well maybe I guess I sure hope I didn't infect a bunch of people in the 5 days since that exposure site was announced".t

Adding some intermittent self-tests through that period could give quicker results for contact tracing, and actually try containment while it's still relevant.

Regular testing of schoolchildren / employees #

Schools are a perfect opportunity for regular rapid tests. Lower risk, but higher value of catching cases early (before they infect too many people in more vulnerable groups). If you are going to return to a regular indoor group activity, it is an easy way to screen that you can do from work! This is again being introduced now, but crazy that it was not considered a year ago. This idea is not new new.

For ticketed events or busy places (supermarkets etc) #

Again, for stores that have been outbreak risks we currently wait on finding someone with PCR tests. You could test people on their way to the supermarket, and then have a test result before they've even finished their shopping! Announce over the overhead speakers "we just detected a positive case, please get PCR tested immediately". Would stores do this? Would customers listen? Both probably unlikely. But that would give much faster indication than the current multi-day lag of a PCR test and then publishing the exposure site and having other people get tests.

Voluntary tests for hypochondriacs #

As we open up, people could self-test as their social bubble expands. After seeing some people out this weekend, I would have loved to have a test at home sometime this week. Instead I am supposed to wait until I am symptomatic, then drive to a testing centre and wait a day?

Absurd comparisons with PCR #

The obsession with 100% perfection guarantees - both in test accuracy and vaccine safety - has been an infuriating part of the response to COVID. Expected value is apparently ignored, leaving us with vaccine supply shortages, public fears about vaccine safety and weird preferential choices, and just in general terrible decisions.

They are not meant to replace PCR, but should definitely be part of our toolkit.


Last updated: Mon 28 Sep, 2021

Disclaimer: I am not any kind of doctor or expert, potentially wrong about plenty of this.

More notes and links on this here