Serologic Response of Nonimmune Subjects to Commercial Salk Vaccine

Abstract

In spite of the widespread use of killed poliomyelitis vaccine during the past 6 years, there are still relatively few data concerning the duration of immunity after a complete course of immunization. Thus, it is as yet not possible to give with assurance recommendations about the need for repeated doses of vaccine in order to maintain adequate protection. Salk 1 has reported an excellent response to 3 doses of vaccine given according to his recommended regimen and reported that antibody to all 3 poliovirus types has persisted at a remarkably stable level for 6 years after the third dose. These most encouraging results are not representative of the experiences of others. However, it should be pointed out that the data of Salk on persistence were obtained from a small group of 13 children who were immunized with a vaccine of high potency that was especially prepared. The persistence of antibody after 4 years in 500 children who participated in the Salk vaccine field trials in 1954 was investigated by Brown and Napier.2 Although many of the subjects had either received additional doses of vaccine or undergone natural poliovirus infection during the intervening period, a significant number still lacked antibody to Types I and III.Since 1955 numerous investigations have been conducted both in the United States and abroad to evaluate the efficacy of vari¬ ous dosage regimens 3'7 and the effect of age upon response811 to commercial vaccines.Certain of these studies include data con¬ cerning the persistence of antibody after primary immunization and one booster.3·4·8 However, the periods of observation are relatively short, not exceeding 2 years, and in none are data reported relative to per¬ sistence after a fourth injection. From the published data certain generalizations seem justified.First, both the response to primary im¬ munization and the persistence of antibody have been much better to Type II than to Types I and III.11·» Second, the persistence of antibody is related to the level achieved after primary immunization which is in turn related to the potency of the ar.tigen employed.1