The reason for the using the entire USA Population for the above is because this Corona Virus started in China and then spread all over the world. It's just like the annual flu (influenza) and the common cold. It's also been over 1.65 years (since Jan 2020) and hence we should not think some people have not been exposed, (which has never happened with the flu or common cold.)
We were told this Covid-19 virus had a really high R0 (R naught) value.
We were also told that you can only "Flatten-the-Curve", NOT "End-the-Curve".
Yet, if anyone were to disagree on not using the entire USA population, they should state what percentage of the USA has NOT been exposed or infected.
Yet, that would take a another random population study like done by California, New York, Ochsner Hospital and the Feds back in May 2020, and that same study would say we are already at herd immunity.
