For those not inclined to decipher entirely the above two IMO informative dissertations, this is my main takeaway:

"They opted to track down and vaccinate the individuals most likely to come in contact with the known cases. Dubbed “ring vaccination” or “surveillance-containment,” this strategy helped clear the final strongholds of smallpox over the next eight years.

It did it by addressing a wrinkle in the herd threshold theorem. That basic equation assumes everyone in a population is equally in contact with one another and spews an infectious virus in the same way."

Meaning the "wrinkle" is about an invalid assumption, and a component in why the opinions in our country to this pandemic are so divided, as nobody knows exactly where the "ring" is.