Part 2. in a series. Death rates in the 2021 Melbourne COVID-19 Delta 2 outbreak start out lower than rates at start of the Sydney 2021 COVID-19 outbreak

 The Pundit is tracking indicator of health damage severity of COVID-19 outbreaks in Australia.

One of these is deaths per 100 infections, or infection fatality ratio.

Starting August 4 2021 there has been rapid spread of a Delta variant outbreak in Melbourne.

Here is a graph of cumulative cases and cumulative deaths over 43 days

For this graph, accumulated case numbers have been divided by 226 before plotting on the vertical axis.

The horizontal axis is days since August 4.

Cases divided by 226 tracks very closely with numbers of total deaths after a lag adjustment of 11 days. (The median time for death after becoming ill is 11 days.)

This suggest an infection fatality ratio of 1/226 or 0.44 percent

Its interesting to compare this evolution with that of the Sydney outbreak:

For this plot, the cumulative cases have been divided by 100 before plotting. They track closely with cumulative deaths from COVID-19 in Greater Sydney.

This close alignment of cases and deaths suggest that the infection fatality rate in Sydney in this 45 day period was 1.0 percent.

This is higher than currently seen in Melbourne.

The subsequent evolution of cases and death curves for the Sydney is interesting:

Between 45 and 91 days the two curves for Sydney — cases and deaths– diverged from one another.

This reveals that  infection fatality ratio is dropping in NSW, possibly because the virus is encountering people who are more likely to be vaccinated because of rapid vaccine rollout.

There are other possible explanations. For example the SARS-CoV2 infection early in the Sydney outbreak may be in local communities with greater than average susceptibility to severe disease (local pockets of low vaccination rates perhaps).

It will be interesting to keep on following this tale of two cities.

At least Melbourne from the perspective of COVID-19 damage, seems to be starting out the outbreak with better health resilience than Sydney .