When I first came to the US as a graduate student, I had to redo all my childhood vaccinations even though I still had visible scars on the injection sites from them. But I had no paperwork confirming that I had been vaccinated back in the USSR 27 years earlier. The really funny part was that it wasn’t the first time I was being re-vaccinated. I’d had to get vaccinated for chickenpox, measles, etc back in Canada when I first arrived and became a student there. And. . . again, being an airheaded student, I didn’t save any paperwork.
I also underwent a very thorough – and quite invasive – medical exam before I was allowed to emigrate.
So I don’t know why people are reacting like this is something new and invented yesterday for the purposes of stoking up fears before the election. Or something that only exists in the US.