Intensive immunization programs : hearings before the Committee on Interstate and Foreign Commerce, House of Representatives, Eighty-seventh Congress, second session on H.R. 10541 a bill to assist states and communities to carry out intensive vaccination programs designed to protect their populations, especially all preschool children, against poliomyelitis, diphtheria, whooping cough, and tetanus, and against other diseases which may in the future become susceptible of practical elimination as a public health problem through such programs. May 15 and 16, 1962