In all those cases there was a pre-existing, widespread social bias and open bigotry against the groups being targeted - which of course doesn't make it right,

In all those cases there was a pre-existing, widespread social bias and open bigotry against the groups being targeted - which of course doesn't make it right, but does explain why such things were tolerated and even thought to be good ideas in those societies. But in most of those cases, I would argue that the intentions of the leadership enacting such policies did not do so out of pure-though-extremely-misguided intentions. They acted in various ways to disenfranchise and disempower (gross understatement in the case of the holocaust!) the groups being targeted, playing to the gallery and entrenching their own power. As I read the sentiment in the US (as an outsider), I find it hard to believe the CDC are playing to the gallery here. I think there is a genuine intention on the part of the CDC (despite the CDC being a key bogeyman in many flavours of fever-dream). The problem is that the culture of secrecy and "for your own good" in the US is so entrenched (because it's soooo much easier than trying to educate folks), that combined with past mistakes, trust has been irrevocably eroded to the extent that everything is doubted by everyone. My own view is that this is symptomatic of a huge malaise in the US and to a lesser (but growing) extent in the rest of the world. Can the idea of "society" function in the face of such mistrust in instututions? I doubt it. We are increasingly voluntarily partitioning ourselves into tribes/bantustans and shrinking the circle of trust. To my mind that model doesn't scale well with population. Bad times ahead.