In the course of trying to prove that it was actually Osama Bin Laden living in that compound outside Abbottabad, the CIA apparently set up a fake Hepatitis B vaccination campaign, which was actually aimed at collecting DNA samples from Bin Laden's children. Working with a Pakistani doctor, they started giving out the first dose of the three-dose vaccine in poor neighborhoods, as a cover, and then, instead of going back to administer the necessary follow-up doses (without which, children are still susceptible to the disease) they moved on to the area where Bin Laden lived and tried to get the doctor inside his compound.

This is bad. Very bad, from a public health perspective. The New York Times story linked above doesn't really get into the implications the CIA's (failed) venture will have for real vaccination campaigns, but Maryn McKenna does a great job of explaining the issues at her Wired blog: