I would expect some of this has roots in anti-vaxx, but is it possible more of this vests in the increase in social mobility (between states, between economies) and therefore the rise in out-of-herd contact risks?
Edit: This is inclusive of foreign workers with H1B and other working visas.
Regardless, unless you are an immigration lawyer and extreme pendant, H1b holders are immigrants.
The US classification of immigration intent is not relevant to whether they are immigrants in the common sense of the word.
But it is relevant in the context of the statement the parent was replying to:
> US immigrants are required to have the MMR vaccine, among others.
but I did mean in-the-wide too; i think since we started down the vaccines as herd immunity game in the 50s and 60s we now have more routine travel and the rate of change here has accellerated. When I was a kid in the 60s few flew, my first flight was at 16 and then no more until 24. Now, I fly 10+ times a year worldwide. Thats only 40 years gap.
Heck according to this data https://data.worldbank.org/indicator/sh.imm.meas
In 1980 even Germany had 25% vaccination coverage but I'm guessing it could include East Germany too so a developer in their mid 30's simply might not been vaccinated at a young age and if they didn't travel to high risk countries, joined the military or worked with at risk groups it was never caught.
But it finds a solid ground much more effectively when herd immunity is compromised, as it is today in many places, thanks to the anti-vax delusion.