Since we're all now amateur epidemiologists, some other assumptions
which caught my eye in the Doherty report:
p10: "partial TTIQ effectiveness" is based on 700 cases per day. At
thousands of cases per day there will be effectively no "TTQ", just the
"I" provided by lockdown measures.
p22: assumption that delta and alpha variants are equally severe. In
contrast, the Sheikh paper referenced in the Doherty report finds delta
is "associated with an increased risk of COVID-19 hospital admission:
hazard ratio 1.85".
p30: assumption that children aged 5-14 show reduced onward
transmission, seems to be invalidated by data from current Victorian
outbreak
p40: assumption that cases are infected but not infectious for 2.5 days,
data from Victorian outbreak suggests 1-1.5 days
p40: asymptomatic cases are 50% less transmissive, claimed without
supporting data
p41: it is unclear whether deaths at home are modelled, or only deaths
within the healthcare system
p20, table 5.6: This shows 5.4% of unvac <16 yrs developing a
symptomatic infection but only 2.8% of unvac 16-39 yrs developing a
symptomatic infection. This is clearly misleading and could be due to
the 180 day limit on the forecast.
Each of the assumptions above result in the model predicting a much
slower rate of transmission within the community. And therefore
predicting a flatter curve, lower peaks, less strain on the health care
system and greater effectiveness of TTIQ. These factors are all mutually
reinforcing and synergise to produce a socially acceptable outcome.
While I acknowledge that we can't remain locked down forever, I am
doubtful that the reality over the next 6 months will look anything like
rosy picture painted by the Doherty modelling.
On the up side Stephen, Table S2.5 represents a 92% reduction in
mortality rate from the starting point of approx 1%, so a final
mortality rate of 0.1% rather than your interpretation of a total
mortality rate of 8%.
Richard.
On 2021-08-27 01:59, Stephen Loosley wrote:
The Doherty Model National Plan
https://www.doherty.edu.au/uploads/content_doc/DohertyModelling_NationalPlan_and_Addendum_20210810.pdf
Quote: (Page 13)
"Dynamics and consequences given timing of transition to Phase B
"Epidemic simulations assume a population size of 24 million. Infection
outputs reflect the range of results observed across 20-30 separate
model runs for each scenario. We assume that a single outbreak
involving 30 individuals initiates community transmission at the time
of transition to Phase B, once target vaccine coverage is achieved.
Each simulation is run for 180 days after this initiating date ...
"Figure 2.1: Epidemic growth to 180 days given transition to Phase B
leading to established community transmission for the threshold
coverage targets of 50, 60, 70 and 80%, with vaccine allocation
according to the 'Oldest first' strategy.." (end quote)
Now, two of their four scenario graphs barely flatten off at 60,000 new
infections a day after their 180 day study limit.
In other words ..
The Doherty Model does not even guess at our likely opened-up Phase B
daily infection rates will be after six months .. other than to note
that the predicted infection rates will be something more than 60,000
people infected every day in Australia.
On Page 25, the Model for Delta predicts if everyone is fully
vaccinated, between 8% and 10% of Australians will die.
That sounds like a wonderful plan for opening up, Mr Morrison.
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