Version 2 of the Actuarial Society COVID-19 model was released on Tuesday

The Actuarial Society of South Africa (ASSA) released version 2 of their model on Tuesday and I attended a most interesting presentation on the model and broader issues related to the COVID-19 pandemic. The model itself and the accompanying paper are very impressive and well worth a read.  

However, the model does little to assist anyone trying to come up with a better understanding of how the pandemic might play out in South Africa over the next two months, six months or twelve months.

The paper sets out 30 scenarios for the pandemic in South Africa but with a disclaimer that the scenarios do not represent a range of possible outcomes but rather the impact of varying the key parameters used by the model. 

The graph below compares the 7-day average of daily reported COVID-19 deaths for each of the 30 ASSA model scenarios with the NMG model run using the default parameter assumptions. The NMG model is shown as the red dashed line. The actual reported deaths are also plotted.

What is evident from the comparison is that none of the 30 ASSA scenarios give similar results to the NMG model and that the NMG model results are at the low end of the scenarios given.

The paper accompanying the ASSA model includes a section where they highlight four specific scenarios that 'broadly reflect the range of views held by actuaries who have contributed to the research'. These four scenarios are compared to the NMG model in the graph below:

If I ignore the two extreme scenarios and compare the middle two scenarios with the NMG model, I could conclude that we are perhaps being a little optimistic with the NMG default parameter assumptions. It is always good to be aware of this possibility and we will need to monitor the data closely over the next few weeks to see if daily reported deaths have indeed peaked (as forecast by the NMG default parameters).

What is interesting is that all four scenarios show the pandemic as largely over by Christmas. While there is a risk of a second wave, the extent of the infections forecast in the scenarios for the first wave would make a significant second wave less likely.


14 August 2020



Comments

  1. UnknownAugust 14, 2020 at 2:11 PM

    Thanks, wonder whether specific provision should be built in all models for excess deaths, also given differential reporting, rgds

    ReplyDelete
    Replies
    1. GaryIanAugust 26, 2020 at 6:53 PM

      I have come to the same conclusion after seeing the reported deaths in Gauteng falling way short on the Western Cape. The latest release of the NMg model makes this adjustment

      Delete

Post a Comment

Popular posts from this blog

Update on COVID 19 tracking in SA

Image
An analysis of the weekly deaths from natural causes as reported by the SA Medical Research Council (SAMRC) shows evidence of elevated excess deaths over the winter months of 2022. The graph below shows the weekly deaths reported by SAMRC in excess of the average weekly deaths reported between 1 January 2020 and 15 March 2020.  The COVID-19 hospital deaths as reported by the National Institute for Communicable Diseases (NICD) would appear to follow a similar pattern to that shown by the SAMRC excess deaths but with a more muted 5th wave. Anecdotally, the number of COVID-19 cases appear to be on the rise in South Africa although COVID-19 cases are no longer reported on a regular basis (outside of a hospital setting).  The above graphs show that the COVID-19 disease severity is certainly not near the levels experienced in the first three waves. 4 November 2022
Read more

Time to consider the 4th wave?

Image
We have updated the NMG model to consider various scenarios for the 4th wave of COVID-19 infections for South Africa. You can access the model at  https://nmg-covid-19.sctechnology.co.za/ It will take a sustained viral propagation above a threshold speed to generate a noticeable 4th wave. The first 4th wave scenario is displayed below assuming a viral propagation speed of Rt = 3.0 for a period of 100 days starting on 15 October 2021.  The second scenario shows the impact of a viral propagation speed of Rt = 4.0 for the 4th wave. It is important to note that to reach Rt = 4.0 in the current South African population would require a viral strain with a basic reproduction number of over 12 (some four times the speed of the original SARS-CoV-2 virus). This calculation is based on the NMG model, where some 67.5% of the South African population is assumed to have built up immunity to reinfection due to infection over the first three waves.  A material 4th wave could be caused by...
Read more

Is the third wave less deadly?

Image
KwaZulu Natal has overtaken both Gauteng and the Western Cape in the number of reported COVID-19 deaths. However, the deaths in KwaZulu Natal are still well off the peak experienced in the second wave.  The modeling done by NMG shows that the reported COVID-19 deaths are still lagging way behind what is projected for the third wave based on the reported infections. This would indicate that the likelihood of dying if infected in the third wave has not been as high as for the first two waves. This may be due to greater levels of prior exposure to the virus of those infected due to either vaccination or prior infection. It could also be the result of more effective medical treatment. 19 August 2021
Read more