Pakistan finished its latest three-day anti-polio campaign Wednesday, deploying thousands of health workers across a nation where officials say militancy, a massive migrant population and fears about vaccines have kept the crippling virus alive.

But this round of outreach was also shadowed by a new, U.S.-made complication: revelations that the CIA sponsored a vaccination program to try to collect DNA from Osama bin Laden’s family members before U.S. commandos killed the al-Qaeda leader at a compound in northern Pakistan in May.