Back to the future -- looking at New South Wales as a prediction of Victorian epidemic progress

This is a post to collect useful comparisons of Sydney and Melbourne epidemic trajectories. The post will grow over time, but let's start with a recent Tweet by Data Base Raven :

This graphic confirms that vaccine protection provides a strong prediction of the turn of daily case number curves, and that infection protection of near 50 percent of the active community makes a measurable effect in damping down virus spread. This is completely as expected from theoretical disease models for epidemic spread of infections.

Current status of outbreaks 15 October data (H/T Matt Hopcraft graphics)

Putting aside for the moment the terrible current impact on afflicted families and a stressed hospital system, there still good reason for hope about the next week from the graphs displayed above.

Estimates still have effective reproduction rate (Rt, also called transmission potential) in Victoria near 1 and trending down. Daily new Victorian cases are currently high (14 October) but they are at the peak of a clear weekly pulsing pattern (?caused by weekend social gatherings?) . 

The underlying driver -- vaccine coverage -- of epidemic mitigation and control continues to improve and targets of 70 percent eligible population coverage are close. 

This means that return of civic freedoms can start and "bargains" with the populace can be met. The Pundit hopes that serious economic damage from tough government decisions can soon start to be softened.

Disease severity seems milder in Melbourne.

Differences can be seen between the states in hospitalisation rates. Here are some more Data Base Raven graphs showing this (at 20 October 2021):

These are interesting for comparing relative hospitalisation levels from cases. Victoria is much lower that New South Wales and trending to even lower percentage hospitalisation. As similar pattern is seen with ICU percentage. It seems that poor vaccine coverage early in the New South Wales outbreak allowed much more frequent severe disease outcomes.

Covid19 data  have good graphic showing this:

Victoria has lower ICU occupancy despite higher peak case numbers than New South Wales.

Vaccination is shielding Victoria from severe disease

Additional analysis of disease severity trends.

There is confirmation of these trends for New South Wales in government weekly epidemiology surveillance reports which give weekly hospitalisation and case numbers. These are more directly related to disease severity than hospitalisation ratios used by the Raven which are affected by shortness of stay in hospital. The Pundit calculated the following ratio values based on these reports:

Week 28 ends 17 July, Week 39 ends 2 October

These show a trend of improvement, indicating on average disease is less severe.

Age distribution of diagnosed cases.

There is much comment about reasons for differences between the two outbreaks, and suggestions made that lower hospitalisation rates prevail in Victoria, as that the average age of cases is lower in that state.

Stats on 30558 "active cases" on 15 October for Victoria, and 53153 outbreak cases in New South Wales to 25 Sept (from NSW weekly Surveillance report 38) were compared. A graph of this comparison is this:

The Pundit sees no obvious explanation from this graph for age differences in infection prevalence to explain lower hospitalisation impact in Victoria than for the New South Wales outbreak. It seems likely then, that higher vaccination coverage and better immunity across all age groups could be causing the lower hospital occupancy in Victoria than seen with the New South Wales outbreak.