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A live vaccine against pertussis.

Animal experiments have shown that oral administration of live Bordetella pertussis induces a protective immune response. The biological properties of a nonpathogenic Bordetella pertussis strain, its toxicity and immunogenicity in mice were investigated. Comparative studies of the intraperitoneal and the oral route of immunization have shown that there was high mortality following intraperitoneal administration of the highest dose, whereas none of the doses of vaccine given orally led to appreciably higher mortality than that observed in control animals. The oral method of immunization when employing a stable, non-toxic, live vaccine strain, may be of value for women of child-bearing age, pregnant women, and for pediatric and nursing personnel exposed to the risk of pertussis infection. Infants may benefit by transplacentally conferred protection as well as being actively immunized at an early age after birth.