Environment Magazine

Projecting Global Deaths from Covid19

Posted on the 18 March 2020 by Bradshaw @conservbytes

Projecting global deaths from covid19

I know that it’s not the best way to project expected deaths from a pandemic disease, but being something of a demographer, I just couldn’t help myself.

I therefore took the liberty of punching in some basic probabilities into our world population model to see how many people could potentially die from covid19. But this is not an epidemiological model, so I’m probably vastly over-estimating the total death rates.

Nonetheless, the results were revealing.

I first took the expected mortality by age class based on the Chinese data so far. I then assumed a worst-case scenario of a 60% infection rate (i.e., 3 out of 5 of us will eventually catch the virus). I assumed these values across the entire globe (not taking into account greater or lesser susceptibility or probability of death among countries or regions).

I also considered two more scenarios: (i) double the mortality rate (in each age class), and (ii) the disease outbreak lasting two years instead of just one.

The graph below shows the four different outcomes based on these scenarios relative to the baseline (no covid):

Projecting global deaths from covid19

What do these projections mean in terms of expected global population by 2030? Well, as you can see, even the worst-case scenario isn’t really going to change our trajectory, but using these infection and mortality rates, there are surprisingly a lot of projected deaths:

  • covid19 lasting 1 year at the mortality rates given above: 78.21 million deaths, or 0.97% of the global population in the absence of the disease
  • covid19 lasting 2 years (mortality rates as above): 156.08 million deaths, or 1.93% of the global population
  • covid19 lasting 1 year at double the mortality rates given above: 156.41 million deaths, or 1.94% of the global population in the absence of the disease
  • covid19 lasting 2 years at double the mortality rates given above: 301.74 million deaths, or 3.74% of the global population in the absence of the disease

That’s a lot of people! Wash your hands.

** ADDENDUM **

A good friend in the health field suggested that with a R0 closer to 2.5, there’s a likely infection probability of 0.9 in the first year, followed by 0.1 in the following. Using these parameters instead (with the base mortality rate by age class), the prediction is 129.85 million deaths (1.61% of global population).

CJA Bradshaw


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