# COVID Odyssey: OZ Adventure ~ COVID OdOZy

We look at the outbreak of COVID-19 in Australia.

In the Vir[tu]al World Tour we estimated that in Australia r = 1.27, where r is the daily rate of spread of COVID-19 used to calculate Ro, the average number of people one person infected with COVID-19 may infect.

Today we look at the following two tables based on Australian case numbers: For an explanation of the above values, please see:
COVID Odyssey: African Safari ~ Big game shooting (with a camera)

We see in the last column that there is only one value close to 1.4 (1.398348).

In the Vir[tu]al World Tour we estimated that in Australia, r = 1.27.

We see in the last column that there are a number of estimated values of r close to 1.27. The big jump in case numbers from day 58 to Day 59 meant that this for r value did not fit closely to the actual case numbers for preceding days.

Over two 5-day cycles (the infectious period), we see below that r is better estimated as around 1.24 (also see previous two columns in the above table). The above table uses two different starting values and two values for r, both providing reasonable estimates for the cumulative case numbers.

We conclude that in Australia in March for the above dates, r was close to 1.24.

Since this value of r was the consistently highest value, we use this to estimate Ro.

For two cycles (infectiuos period) we use Re#2 from the table below.

Using r = 1.24, we obtain Ro ~ 3.36787 which we round to 3.4.

One person in Australia with COVID-19 is likely to infect on average 3.4 other people during this outbreak.

Using r = 1.27, we obtain Ro ~ 3.77483 which we round to 3.8.

We conclude that in Australia one person with COVID-19 is likely to infect 3.4 to 3.8 other people.

Update:
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For a comparison (averaged values) for Australia and other countries, see:
COVIDWorldAvAlpha
COVIDWorldAvRanked
COVIDWorldAvNewRanked4
COVIDWorldAvNewAlpha4
COVID Odyssey Ro update: Occam’s Razor~ A close shave: In NZ is Ro ~ 3, 4, or 6? What are Ro values worldwide?
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For many other countries, including New Zealand, we have seen Ro ~6 using r = SQRT(2). Perhaps it is useful to use the range in the above table to estimate Ro?
For r = 1.27 [Australia] this would give a range for Ro of 3.3 to 3.8 (1 d.p.).
This provides an estimated range for Ro, over a 5-day cycle, ranging from an estimate over one cycle with no rate of decay (r^5), and and estimate over two cycles where the decay rate is 1/r using the formula for Re#2 at the top of the above table. This range includes the 3.4 value for Re#2 calculated using r = 1.24.

For r = SQRT(2) [New Zealand] this would give a range of 5.7 to 6 (1 d.p.).
This range includes the Re#2 value of 5.8 for r = 1.4.

The graph below compares these: I share my posts at:
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