Can’t answer that without some research. The larger question [rhetorical] is why these foreign disease spreaders - assuming that’s the case - are permitted to roam free.
Probably not foreigners. In those counties, more likely Hasidim
I guess controlled immigration, with medical inspections and quarantines, is so 19th-century.
The problem is there are two forms of Polio vaccine.
The first is the Dr Salk inactivated vaccine. It works but is expensive and requires refrigeration. This is what is given to Americans and first world nations.
The second is the oral weakened virus. This is a virus that is a live virus but is weakened so it doesn’t cause polio but gives immunity. Costs pennys to make and can be stored without refrigeration. This is given to the third world.
The problem with the oral virus is occasionally the weakened virus becomes activated in about 1 in a million people. They don’t get polio but can pass it to other people. This is the polio strain that is infecting NY. Someone went to a foreign country and picked up the oral strain.
I can’t remember and I just got revaccinated with ALL childhood vax’s too. Required after a bone marrow transplant. Need to check on that at my appt next month