[NittanyLion]

Your examples are not all inclusive.

True enough. But I was just attempting to illustrate that conceptually there is such a thing as herd immunity.

[jwalsh07]

I think the word immunity throws people. At certain vaccination levels the probabilities become logarithmic but those levels differ for different viruses and are considerably different for bacteria. But I understand your point.

I'm neither a big pro vax guy or a big anti vax guy. I basically favor most childhood vaccinations though the only ones I had as a child was polio and smallpox but draw a line when government wants to mandate vaccinations for my grandkids to prevent sexually transmitted diseases.