The number of cases is well below the percentage we’re told we need for herd immunity, yet we’re seeing signs of herd immunity. This supports the theory that there is a certain amount of immunity pre-existing in the population, probably because of exposure to other coronaviruses.
What signs are you seeing of herd immunity? Once the herd immunity threshold is crossed - by definition - the Rt value drops below 1. Rt is absolutely NOT anywhere NEAR below 1. Cases, hospitalizations, and deaths are all rising with the turn in weather, just as expected.
A vaccine ends this problem, along with all the other problems caused by the botched responses from the (mostly Democrat) governors. Thankfully, two safe and effective vaccines are here and waiting on their emergency use authorizations from FDA. And now that there isn’t an election looming, the FDA may actually get off its collective hind quarters and actually issue them.
The number of cases is well below the percentage we’re told we need for herd immunity, yet we’re seeing signs of herd immunity. This supports the theory that there is a certain amount of immunity pre-existing in the population, probably because of exposure to other coronaviruses.
Innate immunity will ward off most low level exposures for most people.
As for the rest...
At least around my region (mid-south, USA) outside of health care pro's and other people likely to be exposed to COVID-19 on a recurring basis, most tests are symptom driven. Local health departments have been offering free COVID-19 testing, for example, now with droves of requests, but, you have to have symptoms to qualify. My wife and daughter had symptoms, and I was of course then also likely to be infected by whatever they already displayed symptoms of, so we all went and got tested. (This was B4 the Health Depts. started offering regular free testing.) Our symptoms were noted, temperatures taken, meds taken already noted, etc. We all tested negative -- results 3 days later -- it was some other virus. (I really got whacked - still have residual chest congestion. But, it is pretty certain we did not have COVID-19).
However, MANY (most?) people infected are asymptomatic and so never become a "case" because they are not tested. Therefor I can go along with some degree of herd immunity from the above (unreported infections, and exposure to similar coronaviruses) in addition to innate. However, judging by the way many of these outbreaks are progressing despite fairly strong mitigation (IL for example), I think that "herd immunity" is rather limited, and viral loads are increasing and overwhelming innate defenses.
The testing being done, in spite of the great increase therin, is not really capable of serving as a measure of Covid spread. It would,if it were done randomly and continuously across the population, or if it were done in such volume as to test everyone regularly. But neither is true.
We can be sure that there are vastly more infections than are showing up in tests, nearly all of them without symptoms. Thats where Covid is “hiding”, in that great mass of symptomless people, until once in a while, fairly rarely, someone gets tested for whatever reason.