I concluded herd immunity had arrived several weeks back, based upon early readings of the wildly exaggerated and horrible figures out of London, followed by severe reductions, and about which Fauci and friends were dissembling. To go from 2.2 million down to ~60,000 deaths is quite a failure on the part of conventional models, and should bring distrust about what they forecast for the near future.
A simple, though error-filled computation of one infected person infecting one additional person per day, over a month, while the other infected person(s) likewise infect one each additional person per day, you wind up with a rapidly expanding population of infected people, reaching over a billion infected people within 30 days. Of course that is unrealistic as you quickly run out of non-infected people to infect, long before reaching a billion. But consider we had a quarter-million people arriving into the USA from China (as new arrivals or returns from family visits) BEFORE Trump shut the border. How many of them were infected? Nobody knows, but if only 10% were infected, that's 25,000 infected people, spreading across the land. By the one-person-daily preliminary calculation above, we could expect a tremendous number of people infected over the period from November through January. And aside from the problems you note in the study under question, the numbers of infected-asymptomatic should be even larger still, maybe 10, 100 or 1000 times as many, percent-adjusted for the full population.
Now, I'm retired from university teaching of such as population dynamics and environmental issues, including a bit of epidemiology, but such as I describe above could be organized into yet another computer model, and with some careful presumptions, my intuition suggests both high and low numbers of infected-asymptomatic-immune people to be even greater than what that study concluded. Which means,
1) the death rates of the Wu-Flu are an even smaller percentage of those who got infected.
2) we closed the border after "the horses left the barn" (or the quarter million ran into the barn) so to speak.
3) all the isolations, distancing, masking and shut-downs happened only AFTER the major sweep and spread of infections took place.
An incredible number of people were already infected by the end of January, but the vast majority recovered or never showed symptoms.
This suggests, strongly, that herd immunity has been upon us probably since early February, that no vaccine is necessary (and who in their right mind would take it, after all the despotic revelations about Fauci and Bill Gates, their wish for "vaccine certificates" and such), and that the numbers from the CDC cannot be trusted anymore (they began including deaths from all different causes into WuFlu category, without any testing, with money offered to hospitals for doing so). From this it is very clear, the nation should emerge from lock-downs immediately, to face the very real threat and danger now posed by 23 million new unemployed, with massive small business bankruptcies, home forclosures, a new group of impovershed people, and all the morbidity and mortality that attends to economic devastation and depression.
Also the unmasking of so many tin-pot dictators at our state and local levels, wishing to punish people for ordinary social behavior, is disgusting, and yet another reason to remove this issue from the hands of the medical and virological professions, who have done a grave disservice to the nation, and the world.
I predict, a year from now, the medical and academic professions, and the Communist Chinese, will have HELL to pay for this disaster they foisted upon the nation. If this had been treated more rationally like prior corona viruses from China, in a manner similar to how Sweden did (no lockdowns or ubiquious anti-social distancing, masking, etc.), we would be at about the same situation in terms of deaths as we are today. There are no overwhelmed hospitals, with plenty of available beds, the ventillator hysteria calmed down when thousands of them remain unused, and so forth. And there is NO evidence that this reduction is due to any of the lockdowns, distancing or masking. The nation got a huge dose of infections spreading across the land by the end of January, and somewhat similar to other flu episodes. It killed a lot of older people with serious pre-existing conditions, but not in numbers significantly larger than last year's flu season, which claimed ~80,000. What remains unusual is only that young people and children remained largely unscathed, which is not so typical of infectious epidemics.