The Outer Colony vaccination program was a free school vaccination program in the Outer Colonies conducted by the Colonial Administration Authority. The program regularly cataloged DNA traces from the disposed injectors. While colonists often avoided registering births and deaths and even paying taxes, most took advantage of the free vaccinations. As a result, the program held the largest DNA database of the human population. The database was used by Dr. Catherine Halsey to screen the ideal candidates for the SPARTAN-II Program.