Given the laxity of our pandemic response so far, I'm fairly skeptical of this theory in the US at least. We can't even force people to wear masks or lock down,

Given the laxity of our pandemic response so far, I'm fairly skeptical of this theory in the US at least. We can't even force people to wear masks or lock down, why would we be able to force them to get vaccines? Hell, we're not even doing a great job getting vaccines to people who want them. And the business community sure as hell aren't going to want any barriers to people traveling. Their primary concerns will be that there is at least the illusion of safety and that they are indemnified.