Induction of long-term immunity to paralytic poliomyelitis by use of non-infectious vaccine.

Naturally acquired immunity to paralytic poliomyelitis, which is of long duration, is associated with serum antibody, immunological memory, or both. Persistence of circulating antibody is reassuring but not essential for long-term protection. Immunological memory induced by killed poliovirus vaccine is similar to that induced by infection, which is not a prerequisite for the induction of long-term immunity. Animal studies of experimental vaccines indicate that some antigenic components of poliovirus induce immunological memory without producing detectable antibody; killed poliovirus vaccine has the same effect in man. Killed vaccine containing 40, 8, and 32 D-antigen units of poliovirus types 1, 2, and 3, respectively, protects all recipients in both one-dose and two-dose schedules. This means that either schedule can be chosen to fit in with local immunisation programmes and thus reduce costs and increase population coverage.