There is a Scottish professor (can't remember his name) has some position to do with health in the Scottish government. Comes across as knowing his stuff (could be just a good bull sh........) and has been on the radio several times over the last few months. He explains Covid risk like this.
If we give Covid to 100 adults in the UK selected at random, 4% of them would become very ill requiring hospitalization, and 1% of the 100 would die. He said the 1% number is gradually coming down with improvements in treatment, so it is probably around 0.8% now.
I have heard him making this statement several times and no one ever challenges him so I assume he has not just made these numbers up and must have got them from somewhere reputable.
I think he is wrong ... And this is why. ..And it hinges on whether the infection "takes "with that patient. If he waits until there is a positive diagnosis, I would suggest that 80% will get treated at home,and 20% will need hospital care of which 8% extra care and 4% of the total succumb . The 4% not dieing will have chronic or extended disability.
The only Proof that a person has CV19 is the active positive test using the accepted accepted methods ..and this shows the 35M globally to date have been infected . 1M have died, 7.5M are undergoing treatment and 4% of those finished treatment have died. That some countries , especially the UK will not present statistics of cured ,dies not help, but the numbers globally are sufficient to ignore that error . That 4% has gradually come down from the very painful 11% in April ..due to two reasons . improved treatment and increased testing including those of non serious cases.
Now the number of people who have been exposed might be into the Billions . The numbers who might have got some symptoms ,but never developed into anything major might be 100s of millions and some of these might show some antibody responses from some fragments of RNA code.. but these all all speculative. ..And worse, there is no evidence that these persons will be immune if they get a proper hit of viruses.
Putting it in engineering terms, you would not base a space program on the informed speculation of these population surveys.