How far are we from the peak?
Yesterday, the number of new cases in South Africa was 8124. What do you think the number of new cases will be on the day that we peak in the country?
I mean the daily peak infections, not the cumulative. Please close your eyes for a moment, when you try to imagine what that number might mean.
We have seen a sharp increase in Covid-19 cases in the last week. It is getting quite close to home when one hears daily about first-hand accounts of people who have lost their lives to the disease or those who have suffered some of the serious symptoms while in quarantine; many of these are young people and hence not considered vulnerable at all.
As the number of cases rise, we are bound to ask the question about how close we may be to the peak. Are we near the peak, half-way there, less than half-way?
When will we reach the peak? In three weeks, a month, two months?
This piece offers some sobering reflections:
It is now 118 days from our first infection. The figures released yesterday are as follows:
- 159 333 positive cases
- 76 025 total recoveries
- 2749 total deaths
- 8124 new cases
There are many non-linear dynamics that affect the spread of the disease and that requires epidemiological type models. If one wanted to explore the latter then one can try here: https://exchange.iseesystems.com/public/shamim/cosimpol/index.html#page1
However, for the purpose of this reflection let’s do some simple maths with simplifications and approximations:
- As much as we have tipped the 150 000 cases, this is less than a scratch.
- For the epidemic to “burn itself” out we have to traverse say 55 million cases (crude SA population assumption). As much as we talk of the pandemic being with us for many months, the general perspective in the popular discourse is that we shall be over the worst by around September?
- So that’s 90 days to traverse say 45 million if we assume that the remaining 10 million cases will occur over a longer period, say, the next 18 months.
- This means that the infection rate at the peak will be 45 million cases / 90 days = 500 000 cases. This is if we had an equal number of infections each day for 90 days. That’s a rectangle and not a curve actually. So, we should probably increase that to about 700 000 cases a day on the day that the infection peaks. That’s a far cry from the 8300 cases we are at now.
- Some may say that we should reduce that for herd immunity once we are at about 60%. Strictly speaking we should not assume herd immunity, rather our models should hypothesise when and at what level we shall achieve herd immunity. Again, for purposes of simplicity lets assume that 60% is when we get immunity. Let’s recalculate:
- 60% of 55 million = 30 million. Again, let’s assume 10 million cases will occur over a longer period of say 18 months. That means we have to traverse 20 million cases over 90 days to the end of September. Again, a crude (rectangles shape) means 20 million / 90 days = 222 222 cases.
- Adjust that for a curve brings us to a peak of say 300 000 cases per day.
Consider what that means when it appears that hospitals are already full, ICU's are full in some provinces, and that includes private facilities. That’s with daily infections of less than 9000 a day. Scary stuff indeed.
This is a serious pandemic and we have to take it very seriously. With much of our economic activity having been resumed, the need for physical distancing, hand-washing, sanitising with 70% + aclohol, wearing of masks and following the necessary protocols are absolutely important. None of these will change the epidemiological fundamentals of the pandemic spread but it will impact the duration of the pandemic…so as much as we want to flatten the curve, perhaps we should focus on “stretching the curve” – it buys us time. Let’s apply all the protocols, and pray!