Routine Immunization with Orally Administered Attenuated Poliovirus

In the United States, studies with living poliovirus vaccines have been conducted within institutions and families under ideal conditions. The present study explored the feasibility of early immunization of normal children living in a low-income area of an American city. Most of the 850 children 1 1/2 months to 6 years old entering the study were susceptible to poliomyelitis. One, two, or three types of vaccine given orally at monthly intervals yielded significant antibody responses in 93 to 100 % of children who had not yet lost maternal antibodies, and in 84 to 100% of children without antibodies. Although this was not an evaluation of vaccine safety, community surveillance was maintained; no case of poliomyelitis in Philadelphia occurred in a person vaccinated by this method or in his household. The vaccines were efficacious, according to serologic evidence, in conferring immunity to poliomyelitis.