I'm not the font of all knowledge but here's my understanding.
(I’m going to use some made-up numbers that aren’t correct but are plausible given current estimates here.)
Suppose we have 100 cases.
Current evidence suggests these may divide up as follows:
- 20 will be asymptomatic.
- 65 will be symptomatic but NOT require hospitalization.
- 15 will be symptomatic and REQUIRE hospitalization.
- From the hospitalized group of 15:
- 3 will need an ICU bed
- 2 will need a ventilator
- 1 will die.
So, deaths will be 1%.
Why Testing Matters
Now suppose you only test SOME of the symptomatic cases say, 50%, what you see is in your group of 40 (65+15 are symptomatic), 15 will require hospitalization (they would be tested and the testing clearly isn’t random) and ultimately 1 will die. Use of this raw testing data says the deaths would be 2.5%. But this would be wrong. We have no way of knowing how wrong until widespread testing occurs. Non-random testing is also then highly unreliable in terms of drawing inferences about what the real proportions above are.
That’s why proper expansive (and if possible random) testing matters.
The Population Death Rate
Clearly if everyone in a population was exposed to C-19 (unvaccinated) the expected death rate would be 1%. There are some reasons to be optimistic in terms of C-19 being affected by heat, the possibility that a vaccine may become available and the measures put in place to slow/prevent its spread. All of these may mean less than 100% of people are liable to contract it. If, say, 30% of the population become exposed we can expect a population death rate of 1% x 30% = 0.3%.
The Death Rate Benefit of Social Distancing/Stay-in-Place
The ultimate death rate is also affected by the number of people who require medical care at any one time. If the demand for ventilators/ICU beds outstrips their availability people will die for want to appropriate medical care. Essentially rather than a lot of people becoming ill all at once this spreads this peak over time and allows more people to benefit from medical attention.
