We had a fire ant infestation in Atlanta when I was young and they would drop these little orange and black pellets out of the sky.
Great fun to go out into the woods with your baseball cap on and let them pop you on the noggin and listen to them whacking into dry leaves.
What info did you post that you are referring to? I read the article but sort of quickly, I need to re-read it, as one of my children had polio vax in the right time period. The next child I didn’t vax because it didn’t set right with me, although I didn’t know the details that I know now.