The field trial set up to test the Salk vaccine was, according to O'Neill, "the most elaborate program of its kind in history, involving 20,000 physicians and public health officers, 64,000 school personnel, and 220,000 volunteers."
Pengujian-pengujian lapangan yang dilakukan Salk menurut O'Neill adalah, "program yang paling saksama dikerjakan sepanjang sejarah di bidang ini, melibatkan 20.000 dokter praktis dan petugas kesehatan masyarakat, 64.000 pegawai sekolah, dan 220.000 sukarelawan."