> why has no other country done it?
Since early in the pandemic many front-line doctors have been successfully reducing hospitalization and death through early treatment with a multi-drug approach. Those are the doctors and researchers that authored the publications I cited in my previous comment, especially [1]. Those doctors had to treat patients early in the pandemic with a very little scientific literature and clinical trials to guide them, hence the world wide collaboration in putting together reasonable guidance based on existing medicine with established efficacy and safety profiles.
They continue to use these techniques - which are being further investigated for efficacy and safety in ongoing clinical trials - but with scarce media coverage compared to the vaccines.
So in many ways countries around the world have been doing it to some degree, but it hasn't been the primary strategy, as you point out. Why hasn't it been the primary strategy? Well that's a good question and tough to answer with any certainty. To speculate, I'd say that vaccines had a tremendous amount of funding and media attention poured into them, more so than any multi-drug therapy regime.
All that said, I would actually like to see someone try it. There are plenty of countries that have little expectation of receiving much vaccine supply this year anyway; they have little to lose. But it's no slam dunk; they face a daunting public education problem first, and then if they somehow solve that puzzle, they'll have to deal with the logistical difficulties.
Against all that, I think vaccines have more than just a marketing advantage. As long as they're reasonably safe and effective, they're a much more practical solution. Of course, what counts as "reasonably safe and effective" is debatable.
But the situation as regards public health policy and messaging is more complicated. Denial is among the most human of emotional patterns; many people do not want to face the possibility that they've contracted a dread disease, and will procrastinate seeking treatment until they are quite ill. Altering that behavior on a large scale strikes me as a very heavy lift; but that is what we would have to do to pursue a public health strategy that leans heavily on early treatment. If you think it's doable anyway, why has no other country done it?
That said, the risk of vaccine escape seems to be real. Perhaps that's why the CDC is telling us to expect boosters.