Piet Streicher PhD Engineering
South Africa is likely to have 4 times fewer deaths compared to Italy due to our younger population. In Italy, 22% of all people are over 65 years of age, and this age group represented 91% of all Covid-19 deaths. In South Africa, only 5% of all people are over 65 years of age. This factor alone could result in South Africa having almost 4 times fewer deaths from Covid-19 (assuming all other factors stay the same).
Initially it was feared that HIV and TB would significantly increase the death rate in SA. At this stage there is no evidence that this factor would be nearly as significant as the age factor for the country as a whole.
The initial exponential growth of Covid-19 in most countries has lead to predictions of large numbers of deaths of between 0.5% and 1% of entire populations. It is now clear that this exponential growth stops much earlier than expected for all countries and that the total deaths within entire populations are more likely to be between 0.005% and 0.15%.
This significantly reduced risk requires a re-evaluation of all mitigation measures. Mitigation measures in itself pose a significant risk to lives. There are sufficient mitigation measures available to South Africa that would pose a negligible risk to lives.
Predicting the total deaths expected in Italy
The daily new Covid-19 cases and new deaths in Italy has been dropping consistently and predictably for the last 40 days (since late March). It is possible to predict the total number of deaths from start to finish with some certainty now.
Figure 1: Plotting the daily new Covid-19 cases and new deaths from late March.
An exponential curve was fitted to the daily new deaths (from 27 March onwards) and this curve was used to project future deaths up to 190 days from the start of the first death. The projected numbers were then summed and added to the current total deaths. As on 5 May the total deaths for Italy from start to 190 days was estimated at 39 328.
The only uncertainty is what effect the lifting of the lockdown will have on the above curve. Italy has started to lift several lockdown measures and so far, there is no indication of a resurgence. Countries without strict lockdown measures such as Sweden also has a drop-off as Italy has, although at a slower rate. In Sweden all schools and most businesses are open, only social distancing and hand hygiene is required and mass gatherings are prevented.
Deaths in Italy by age
When looking at the distribution of deaths by age in Italy it is noticeable that there are very few deaths for people aged 0-49 years. Children particularly are not vulnerable at all. However, for people over 60 years of age, the risk goes up significantly.
Figure 2: Deaths by age category in Italy (source: Statista)
In the USA, 8 out of 10 deaths reported have been in adults 65 years old and older (CDC).
Italy and South African demographics
Italy has a much older population compared to South Africa.
Figure 3: Demographics of Italy and South Africa (source: https://www.cia.gov/library/publications/the-world-factbook/fields/341.html )
Predicting deaths in SA based on data from Italy
If we asume we have the same number of infections in SA as Italy and we assume a South African of a certain age carries the same risk as an Italian of the same age, we can predict the total deaths expected in SA.
Table 1: Calculation hypothetical deaths in SA based on Italy experience and demographic data (own analysis).
Currently my prediction is 10 886 Covid-19 deaths for South Africa for the March-August period. Note that this is 30 times less compared to some initial predictions.
SA had 12 074 known Covid-19 cases and 238 deaths on 14 May. When Italy had 12 462 known cases, they had 827 deaths i.e. a 3.5 times higher death toll. SA had 17 200 known Covid-19 cases and 312 deaths on 19 May. When Italy had 17 660 known cases, they had 1 266 deaths i.e. a 4.1 times higher death toll. It is already clear that our death rate is significantly lower compared to Italy. At this stage there is no indication that HIV and TB will wipe out the age benefit that SA has over Italy.
The exponential growth stops much earlier than initially expected
Most countries see a dramatic change from exponential to linear growth when between 20 and 100 daily new Covid-19 cases for every 1 000 000 people are reached. After this slowdown, daily new cases slowly start to decrease each day.
The implication for South Africa is that we can expect to peak at between 2 000 and 6 000 new Covid-19 cases per day. We could reach this level by mid to late June already and not August/September stated in the media currently. This peak rate is significantly lower compared to the initial models used in SA used to predict hospital beds and ICU beds required. These predictions all need revision, as this was the primary basis for our strict lockdown measures.
Figure 4: Change from exponential to linear growth of top 25 countries (source: 91-divoc.com).
A call for smart mitigation measures
The reduced risk for SA implies that we need to rethink our restrictive lockdown measures. Lockdown measures carry a significant risk to lives as shown by the analysis of a team of actuaries lead by Nick Hudson (Daily Maverick, 5 May). Dr. Glenda Gray reported that malnutrition cases are seen in Baragwanath Hospital for the first time in more than a decade (News24, 16 May). There is little evidence from the 22 April government report “Risk adjusted strategy for economic activity” that the costs of lockdown measures in terms of human lives were modelled.
We need smart and sustainable mitigation measures. People will obey rules that clearly mitigate the disease. People get upset about arbitrary rules that do not mitigate the disease. When there are too many arbitrary rules, people stop following all rules, including those that are needed. It is therefore critical that mitigation measures are seen as necessary. All jobs that feed a family should be regarded as essential. When you prevent a free market, you create a black market. When you introduce too many regulations, people lose respect for all laws.
The measures with the highest benefit and lowest cost include:
- Rigorous testing regardless of symptoms.
- Contact tracing and quarantine of those infected.
- Prevention of mass gatherings: Events where people shout or sing together carry a significant risk.
- Encourage physical distancing and hand hygiene.
- Wearing of masks by all in high risk areas such as public transport, shops and certain work environments, but not during solitary activities (to prevent prolonged wear risks).
- Protection of all vulnerable people such as the elderly.
Measures with a marginal benefit but the highest cost include:
- Preventing people from working.
- Preventing people from doing the solitary leisure activity or exercise of their choice.
In conclusion, our Government should carefully reconsider the costs of mitigation measures considering the reduced number of deaths expected in this analysis. The economic impact of lockdown measures also poses a risk to lives. People need money to buy food and if they don’t eat, they also die. We are already starting to see malnutrition cases in our hospitals. These are difficult decisions to make and I wish our Government all the wisdom in this regard.
Nick Hudson et al, 2020. The mortality and economic effects of Covid-19: Datasets for decision making. Published in Terry Bell, May 5, 2020. Actuaries warn Ramaphosa of a ‘humanitarian disaster to dwarf Covid-19′ if restrictive lockdown is not lifted. Daily Maverick.