October 8, 2020
In this piece, I intend to establish a reasonably accurate estimate for the risk of dying of Covid-19 for the average healthy person under the age of sixty-five.
If we go back to the start of the pandemic, most of the world locked down based on a prediction that the Infection Fatality Rate (IFR) of Covid-19 would be in the region of one per cent.
In the UK, the pandemic modellers at Imperial College London, the group with the greatest influence on Government policy, estimated the IFR at 0.9 percent. In short, they predicted that approximately one in a hundred people infected with the Sars-Cov2 virus would die.
Has this estimate proven accurate? If so, within a world population of between seven and eight billion, we would expect to suffer up to 76 million deaths. So far, there have been just over one million.
Having said this, no-one predicted that everyone could become infected. The Imperial College model suggested that about 80 percent of people would need to be infected before we reached ‘herd immunity.’ I prefer to call it community-wide immunity. We are not cattle.
Which means that we were not going to reach that figure of 76 million. Under this 80 percent model, we might expect to reach 61 million deaths (7.5bn x 0.8 x 0.1). Even with this reduced number, we are a long way short. How long might it take to get to 61 million?
At present, worldwide deaths are running at around 5,000 per day. At this rate, it would take 33 years to reach sixty million deaths. I am not certain what the time limitation is before a pandemic could be considered to have ended. I would imagine that 33 years might be stretching things a little far.
Perhaps a more important point to consider is this. Do we know how many people have been infected up to this point? If so, we can make a better guess at the likely IFR, and your risk of dying.
Dr Mike Ryan, the executive director of the World Health Organization’s health emergencies programme, recently stated the WHO has estimated that 750 million people have been infected worldwide.
If this is the case, calculating the current, rather than the estimated, IFR is pretty straightforward. You simply divide the one million deaths [1,034,068, to be fully accurate], by 750m.
1,034,068/750,000,000 = 0.138 percent.
So, an IFR of 0.138 percent. Which is significantly lower than the initially predicted one per cent. Or, to turn this figure around, according to the WHO figures, if you become infected with Covid-19, there is a one-in-750 chance you will die.
Of course, figures will vary from country to country. In Kenya, for example, the most recent attempt to estimate the IFR showed an exceptionally low rate. A study was done where antibodies for Sars-Cov2 were taken between April and June 2020. It was found that seroprevalence, the number of people showing antibodies, was 5.2 percent. (This will be an underestimate of true infection numbers, as many people do not create antibodies).
This represents an ‘infected’ population of just under three million (2,796,107), and there had been 71 deaths. Which provides an Infection Fatality Ratio of 0.00254 percent. This extremely low rate is, currently, unexplained.
On the other hand, the country with the highest overall death rate based on mortality per million is Peru. The total population of Peru is 32 million, and there have been just over 32,000 deaths. Which is a population fatality rate of almost exactly 0.1 percent. How many people have been infected in Peru in total? Uncertain. However, their IFR is going to end up in excess of 0.1 percent. Not everybody has yet been infected.
This article was posted: Thursday, October 8, 2020 at 3:44 am