Visual explanation for how herd immunity works

Herd immunity works when you have enough people who are immune to a disease, maybe because they already got it or there’s a vaccine, so that the disease can’t spread anymore to those who don’t have a resistance. For The Washington Post, Harry Stevens is back with simulitis to demonstrate how this works in greater detail.

It starts at the individual level, generalizes to a larger group, and then zooms out to the more concrete state level. It ends with an interactive that lets you test the thresholds yourself.

Each step builds on the previous, which provides clarity to an otherwise abstract idea.