Using Social Networks for Behavioral Change

If you're trying to immunize people, or to implement a behavioral change, like safer sex, or reducing smoking, how do you apply the science of Social Networks if you don't know what the network looks like? 
The authors of "Connected" put it this way:  It is often not possible to discern network ties in advance in a population when trying to figure out how best to immunize it. (pg. 133)

So they asked a number of random people to name their acquaintances - and then immunized those acquaintances.  Turns out that the people who have many network links are more likely to be nominated as acquaintances, as opposed to those with few links.  So the people who were nominated by the randomly selected people are more likely to be near the hub than the randomly selected people!  Brilliant!  Can't wait for an opportunity to apply this (smile).