Not long after midnight on May 2, 2011, U.S. Navy SEALs attacked a three-story compound in Abbottabad, Pakistan, raced to the main building's top floor and killed Osama bin Laden. Few mourn the man responsible for the slaughter of many thousands of innocent people worldwide over the years. But the operation that led to his death may yet kill hundreds of thousands more. In its zeal to identify bin Laden or his family, the CIA used a sham hepatitis B vaccination project to collect DNA in the neighborhood where he was hiding. The effort apparently failed, but the violation of trust threatens to set back global public health efforts by decades.