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Comment by exclipy | Hacker News Reader

In Australia earlier this year when infections were happening the rate of single-digits per day, they could trace the source of an infection to a fleeting encounter of two people walking past each other in a shop.

Source: https://www.abc.net.au/news/2021-06-22/covid19-cctv-footage-...

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I haven't followed Australia's progress with COVID-19, so I hope these questions aren't too obvious or bothersome:

Were these single-digit infections all symptomatic, or were they detecting asymptomatic infections too? What is the false positive and false negative rate of the type of testing Australia is doing, and how many people were being tested during this time?

If some of the infections were asymptomatic, is it possible that some of them are false positives, and the fleeting encounter was also a false positive (either a false positive test, or that wasn't the true source of the infection) just due to random chance?

Positives would be re-tested to rule out false positives.

In that period 30k-60k people where being tested in NSW. https://www.covid19data.com.au/nsw

I have not seen widespread data on symptomatic vs unsymptomatic cases however during the most recent NSW surge around 5-7% of new infections ended up presenting to hospital at some stage. Testing was widespread and likely highly compliant - daily testing stats were available, NSW at one point was having 180k tests per day (PCR). People were notified of sites of exposure (or via checkin apps) and asked to test. Given it was PCR, false positives were as you would expect quite low but there were at least 2-3 false positives I recall being discussed in the media.

In answer to your final question - no - they were PCR confirmed cases. There was also a high degree of sequencing occurring to enable clarity on lineage transmission

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