The Mexican Wave: Covid19 in Australia to October

Postscript: For more detailed information and graphs that support/ augment/ supersede my analysis, see https://www.health.gov.au/news/health-alerts/novel-coronavirus-2019-ncov-health-alert/coronavirus-covid-19-current-situation-and-case-numbers

In Queensland we refer to people in the southern states as “Mexicans” (because they’re from “south of the border, down Mexico way” as sung by Gene Autry, Patsy Kline, Patti Page and many others.)

Read on to find why I describe the Australian Covid19 experience from June to October as the Mexican wave.

Worldometers has these plots illustrating the Australian experience:

Figure 1:  Daily new cases

There were (apparently) two waves in Australia.

Figure 2: Cumulative death toll

In four months the death toll increased by 803- more than 770 %! 

We know what went wrong, but the following plots might illustrate it more clearly.

These plots are from statistics from State government websites, such as this one from Victoria: https://www.dhhs.vic.gov.au/victorian-coronavirus-covid-19-data .

All are correct as of 31 October.  They speak for themselves so I will keep my comments to a minimum.

The next figure compares seven day averages of Victorian and all Australian new cases from 25 July to 6 August, at the peak of the “second wave”.

Figure 3: National and Victorian new cases

Until 5 June, Victoria had 1,681 cases.  From then, the new cases began increasing, adding another 18,666 cases to 31 October.  92% of Victorian cases were in this period.

Comparing all states:

Figure 4:  Total cases

Figure 5:  Mortality:

I estimated population figures from March ABS figures.  With almost zero overseas net immigration and very little interstate migration, natural growth remains, which does not change the rates per million by very much at all.

If Victoria was a separate country, its case rate per million would rank it at 127^th, just ahead of Bangla Desh.   

Figure 6:  Case Rate per million people

Its Death Rate per million would rank it at 76^th, just ahead of Turkey.

Figure 7:  Mortality Rate per million people

The next figure shows Case Fatality Rate, the number of deaths per total cases, which is not complete until the pandemic is over.  These figures are for the CFRs to 31 October.

Figure 8: Covid19 Case Fatality Rate

CFR is affected by whether the virus gets into nursing homes and hospitals which have high proportions of vulnerable people.  There was an outbreak of Covid19 in hospitals in northern Tasmania which affected the Tasmanian CFR.

 4.03% of all Victorian cases so far resulted in death.

The figure for all of Australia is 3.29%.

The figure for Australia excluding Victoria is 1.22%.

The virus first entered Australia via overseas travellers, then spread by local transmission.  The next plot compares infections acquired overseas with those acquired locally in Victoria.

Figure 9: Victorian overseas and locally acquired infections

The contrast is stark.  Victoria compares most unfavourably with other states with over 95% of all cases locally acquired. (Data not available for Tasmania and Territories.)

Figure 10:  Percentage of local transmission in larger states

And Victoria has more than 90% of total national local transmission.

Figure 11:  Percentage of national local transmission

Therefore it can be clearly seen that Australia’s “second wave” was really all about Victoria.  This was easily avoidable with strict hotel quarantine and better contact tracing.  There was no second wave in other states, with small outbreaks mostly due to travellers from Victoria.

Perhaps “Mexican” should from now on describe the government of Victoria, but not their long suffering people, and not governments of NSW, Tasmania, or South Australia.

The Mexican Wave is not something we wish to see repeated.

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Tags: Australia, Covid-19, Victoria