Australian Life for the Next 12 months - Some Scenarios

Based on the Doherty Institute Modelling Report

In all the political backwards and forwarding that has been going on lately the detail of what the Doherty epidemiological modelling means for people’s daily lives in the next 12 months has been lost. All organisations should be thinking more deeply about that. Here are some thoughts based on the?modelling report. All the images in this article are from that report unless otherwise indicated.

Before I get into the detail I would like to surface my biases and assumptions:

• I do believe that we cannot keep going with strict lockdowns. That does not mean I believe in the rhetoric of loosening restrictions with community transmission occurring in a low immunity population.
• I believe that once we get to a level of vaccinations where new vaccination rates start to slow significantly that there will be unbearable pressure on governments in Australia to relax restrictions. Hopefully that is at a high overall vaccination rate but I am cynical about that.
• People’s tolerances for strict restrictions is wearing pretty thin and I worry that compliance levels will fall faster than the Doherty modelling has factored in. I believe that part of the current NSW problem has been mixed messaging with an attitude of “ if the government does not think it is that important then why should I bother” from a lot of people. I think this will be more prevalent when we move to lower levels of restrictions.
• The Doherty modelling is an excellent piece of work but politicians have tended to gloss over the fact that the modelers have stated a number of caveats, including updating the model as more real life data comes in. Politicians struggle with the nuance of communicating this to the ordinary citizen.

So lets start with the best case scenario with baseline community restrictions in the Doherty modelling because there is a lot of data in there. Here is a table from page 18 of the report:

The statement before Table 5.1 says:

Health impacts by age group and vaccine status

Central estimates of these health impacts over the first 180 days following established community transmission are provided in the tables below, for ease of comparison across coverage thresholds, allocation strategies, vaccination status and age group. Note that given epidemic stochasticity and uncertainty, these estimates are drawn from a broader range of possible values as demonstrated by the Figures above. All scenarios assume only baseline restrictions and ‘partial’ TTIQ effectiveness.

Baseline restrictions are defined as:?“only minimal density/capacity restrictions, as in NSW March 2021”

The report assumes only partial TTIQ effectiveness (Test, Trace, Isolate, and Quarantine) because once case levels get to a certain level it becomes impossible to adequately carry out. During the latest Victorian outbreak we have had up to 20,000 people in isolation with cases only as high as 30 a day. At 10 times that number TTIQ becomes impossible to maintain fully.

So lets break those numbers down for the 80% vaccinated scenario over 180 days. Those numbers are an average of:

• 1550 symptomatic cases a day (actual cases will be higher).
• 54 hospital admissions per day.
• 11.5 ICU admissions per day.
• 7 deaths a day.

But as the old saying goes “if I have one foot in a bucket of ice and one foot in a bucket of boiling water, on average I am comfortable”. There is devil in the detail and that detail is that:

In a highly vaccinated population initial transmission rates are slow.

In a slow growth situation TTIQ is far more effective, slowing growth of case numbers even more.

But once the growth gets high enough and reaches escape velocity then growth accelerates and TTIQ become less effective, accelerating growth further. So we get an actual picture like this (from figure 2.3 on page 14):

So basically nothing happens for the first 90 days and most of the cases are concentrated in the last 30 days meaning those averages during those 30 days are more like

• 9000 symptomatic cases a day (actual cases will be higher).
• 300 hospital admissions per day.
• 60 ICU admissions per day.
• 40 deaths a day.

with significant variation from the mean as shown by the upper and lower bounds on the graph.

To put that in context Australia has only had just over?37,000 cases in total?since the pandemic began (this modelling is indicating we will see that many cases every 1-2 days, five to six months after we move to just baseline restrictions with 80% of the population vaccinated.

The good news here is that those issues are much less important if you are vaccinated. Here is a table which looks at vaccinated and unvaccinated people in that same modelling data from page 20:

If take two example columns:

• If you are 60:69 you are twelves times as likely to be hospitalised if you are unvaccinated compared to vaccinated people.
• If you are 16-39 you are almost 14 times as likely to be hospitalised if you are unvaccinated compared to vaccinated people

The reality is that unvaccinated people are also accelerating transmission and increasing the risk of infection to vaccinated people.

So this leads us to four basic scenarios:

• Vaccination rates lower than 80% and minimal restrictions (either by governments being less strict or populations being less compliant).
• Vaccination rates lower than 80% and higher restrictions (by governments being strict and higher case rates scaring the general population).
• Vaccination rates higher than 80% and minimal restrictions (either by governments being less strict or populations being less compliant).
• Vaccination rates lower than 80% and higher restrictions (by governments being strict and higher case rates scaring the general population).

At a very high level these scenarios might look like this:

Vaccination rates lower than 80% and minimal restrictions (either by governments being less strict or populations being less compliant).

If you look at table 5.2 above then at vaccination rates of 70% the modelling shows about a 55% increase in hospitalisation, ICU admissions and deaths. Symptomatic cases rise, but not by as much. This is because there is a larger unvaccinated population and their risk ending up with severe problems is higher. Case growth starts earlier and is higher. It is important to note that this modelling still assumes that we progress to 80% vaccination rates. If vaccination rates persisted at 70% the outcomes would be far worse.

Vaccination rates lower than 80% and higher restrictions (by governments being strict or higher case rates scaring the general population).

Harder restrictions would ameliorate the total number of cases and flatten out the curve. So at a 70% vaccination rate the numbers would be somewhere in between the figures in table 5.2 for 70% and 80% vaccination rates. However there would be more uncertainty around travel and the economy. This would either be because a larger percentage of the population was reluctant to be out and about or due to government restrictions and border shutdowns. Again It is important to note that this modelling still assumes that we progress to 80% vaccination rates. If vaccination rates persisted at 70% the outcomes would be far worse.

Vaccination rates higher than 80% and minimal restrictions (either by governments being less strict or populations being less compliant).

This essentially the scenario I have described in detail above. At first it will appear that all is well and we will have very few cases. Then we will reach a tipping point for transmission growth and we will get to fairly high case loads and hospital admissions at the peak. Not high enough to overwhelm our hospital systems but high enough to cause some disruptions to the health system.

Vaccination rates lower than 80% and higher restrictions (by governments being strict or higher case rates scaring the general population)

This is similar to the previous scenario except individual behaviour or government restrictions in response to political pressures will put a break on community and economic activity. The case curve will be flattened and more likely will be a series of foothills than a single peak.

A real world example of all of this is emerging in the UK as shown in the following picture from?the UK Government?on August 11th:

Despite high vaccination rates (and if we had in the number of people with natural immunity from getting infected the total of double vaccinated plus natural immunity would be over 80%) cases have started to rise again after restrictions were reduced.

So what does all this mean?

All organisations and governments should be preparing themselves for more disruption than the surface reporting on vaccination modelling is showing us. In particular we need to be thinking about what happens with:

• Lower than 80% vaccination rates.
• What happens if we get to 80% vaccination rates and transmission starts to rise rapidly 4-6 months later

There is likely to be more health system and economic disruption than people expect even if we do get to 80% vaccination rates.

The other key message is get vaccinated. It lowers the risks we are facing by a huge margin.

I can tell you what behaviour is going to look like:

• Firstly while I am double vaccinated with Astra Zeneca I will be looking to get an mRNA booster as soon as it become available to me.
• Secondly, as for most of us I am getting pretty sick of lock downs but on the other hand I am on the more cautious side of society in this whole pandemic. That is a function of my risk profile (age and previous post viral infection complications) and my previous experience in disease outbreaks in my professional life (see below for details). That means I will be getting out and about as much as possible once the current lock down in Victoria ends. More than I have been doing. That is because I still see a long road ahead of us and higher risks in the future and I don’t think hunkering down for another 12 months is a good idea. So I am going to act while risks are low.
• Thirdly, I will be closely monitoring vaccination rates, government policy and case numbers and getting ready to hunker down again when the next peak starts to appear. Which is almost certain in my view.

Paul Higgins August 12th , 2021

These scenarios are intended as provocations for further discussion and thinking. They should not be taken as specific advice. They are stories about a future that has not happened yet. The Doherty modelling contains a lot of other possibilities and I recommend you also read that in detail. In particular some of the assessment of the other vaccination strategies have worse outcomes.

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P.S. I do not have any medical qualifications but I have experience as a large animal veterinarian in large scale disease outbreaks in animals. I also have experience in preparing for exotic disease outbreaks in animals in my previous role as a director of Animal Health