Good article. We can mess around with numbers for ever, all I guess we know is that a number of people have caught the virus and recovered. Some will have been tested and so know they had the virus and others will have had it without knowing. Is it 50% who have had the virus and now have some level of immunity to what they caught ,I have no idea.
In the USA about 77 million have tested positive and of these about 47 million have recovered and so we know from this that 14.3% probably have some level of natural immunity, assuming they only caught it once and recovered. It's also highly likely that lots of people have had the virus, recovered and never been tested. There are no statistics for this but here in QLD we did a small study to sample people in an area of the Gold Coast. 117 people were tested and 20 were found to be positive even though they showed no symptoms. So if this is typical this 17% could perhaps be added to the 14.3% to give an estimate of 31% who have had the virus and survived. this is similar to the estimate developed by Yale for the proportion of people who have been infected in the USA, quoted in the article. We can however also assume that most of the people who tested positive, 77million, will recover eventually and so this gives 23.4% who will have had the virus and recovered, add to this the estimate of 17% who have recovered without knowing they had been ill then we get to 41% who have had the virus, recovered and gained some immunity. Which is getting close to the 50%.
We also know that about 64% of the population of the USA have been double vaccinated so it's likely that at least 5% of the population will have had the virus, recovered and be vaccinated i.e. 16 million people.
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