COVID-19: Where are we? #3
On 6/4/20, I wrote “Within … 6-8 weeks, we can be back where we were in January, with relatively few cases & their contacts to trace & put into quarantine.” That day, the number of recoveries/day exceeded the number of new cases for the first time.../2
On 6/4/20, I wrote “Within … 6-8 weeks, we can be back where we were in January, with relatively few cases & their contacts to trace & put into quarantine.” That day, the number of recoveries/day exceeded the number of new cases for the first time.../2
The number of new cases dropped to ~100/day, and the following day, covid-19-au.com added a new line illustrating active cases to their Cases, Deaths and Recoveries graph. A week later, the number of new cases halved, to <50/day. ../3 
The graph shows the number of active cases, which, since 5/4/20, has been following a roughly linear trend, reducing by 1,000 cases over the fortnight. The total active cases now stands at 2,333, so we are still on track to hit minimal active cases in another 4-6 weeks. ../4
The data underlying this trend are not very robust, primarily because retesting active cases has not been a priority for many states other than Victoria. Nevertheless, if we assume proportional rates of recovery to those in Victoria, we get the same result. ../5
What about untested cases? The States have now opened up testing, practically to anyone with symptoms. This resulted in an increase in tests, particularly over the last weekend, and a reassuring reduction in the %+ve rate from 3% to 0.3%. ../6
This proportion (0.3%) becomes an estimate of the maximum possible number of background infections in Australia, since it is unlikely that ill people have a lower infection rate than the general population. Nevertheless, that value is 10x the number of confirmed infections. ../7
You can think of the subset who have been tested as a sample of the whole population, and that sample illustrates the efficacy of our social distancing measures across the whole community, whether tested or not. PROVIDED an untested subset is not behaving differently. ../8
It seems plausible, at the very least, that a group that did not cooperate with distancing, might not cooperate with testing, which brings up the need for community-wide screening once we hit minimal active cases. ../9
The tests currently being used amplify the viral genome and are very sensitive, technically demanding and expensive. They are not ideal for community screening. An alternative being trialled measures antibodies people raise against the virus when infected. ../10
Antibodies are not an ideal way of identifying infection because they may not be present in some infected, and they remain present for a period after the infection. As a screening tool, however, they can identify subgroups in which COVID-19 is still spreading. ../11
The antibody tests are relatively cheap and can be very quick, but screening the whole population, possibly repeatedly, is still a major logistic challenge. It would help if the pockets of COVID-19 infections could be identified by another mechanism. ../12
There are at least two possibilities: 1) A case tracking app that identifies social interactions with known infected people; 2) Using the genetic test to screen sewerage. The app depends on a level of govt intrusiveness not seen in Australia before. ../13
It also depends on cooperation – and the main source of infection once we hit minimal active cases is likely to come from uncooperative people. Nevertheless, the information gained would aid the early identification of many new cases before they can spread. ../14
Sewerage testing has the advantage that pockets of infection can be identified, and then tracked up the dendritic pipelines, testing at branch points, to identify a relatively small part of the community for individual testing. ../15
If widespread community testing and a mechanism of identifying outbreaks before they spread widely are not in place before we reach hit minimal active cases and reduce distancing, all we will have achieved is the opportunity to watch exponential spread of the pandemic again.../16
If these services are in place, and border controls, of both people and goods, are improved, it may then be possible to re-open most businesses for trading within Australia, and potentially with other “premium” countries similarly positioned, such as NZ. ../17
Many have been dismayed by the seemingly widespread view presented in the media that restrictions should be relaxed now. This view was not reached independently, and the individuals speaking have affiliations to the same political/media agglomerate. ../18
The infection rates example countries they use to justify their proposed changes in our approach are illustrated in this figure. It should be clear that the effects of social distancing as practised in Australia have resulted in some of the best outcomes in the world. ../19
Their proposals are akin to bailing out of an aircraft, having one’s descent safely slowed by a parachute, and then throwing the parachute away before reaching the ground. They propose to snatch defeat from the jaws of success. ../20
As a result of our relatively successful management of COVID-19 Australia’s stock market (ASX) is performing well. Last week, it had its best trading day in its history. In this case, health is wealth. What we are doing is working: Hold fast. ../21
There is no #21. Keep safe.
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