we lived in a low income housing project. This was the early 1950s, and there were lots and lots of little kids. I got sick a bunch, and continued to do so through my kindergarten year of school. After that, other than routine colds which I almost never get anymore, and a bout of German measles, and occasional influenza, I was almost never sick.

I am very glad we have the vaccines we do. My sons got what was available to them. I recently got the Shingrix vaccine, because shingles is no fun at all. I would likewise get a flu vaccine if needed in the kind of situation you described.

It's hard to say where the cause and effect is, but I've noticed that the people who are most paranoid about germs, who (for instance) always use a tissue to open a public restroom door, seem to get sick a lot more than most.