Antigenicity of a polysaccharide vaccine from neisseria meningitidis administered intranasally

Polysaccharide vaccine from group C Neisseria meningitidis was administered in- tranasally to three groups of approximately 20 men each. The antigen, 50 pg (groups I and II) or 200 pg (group III), was given in one dose, and the subjects were studied for approximately five weeks. Although slight tearing and conjunctival redness was observed in most subjects after vaccination, only three men in the first group complained of mild ocular and nasal symptoms. No other allergic or toxic reactions were observed. Two weeks after vaccination titers of serum HA antibody to group C meningococci of 4:8 were observed in 45%, 29%, and 70% of men in groups I, II, and III, respectively. A rise in antibody after vaccination was also detected by the bactericidal test, but no detectable complement-fixing antibody developed. The intranasal vaccine did not produce significant rises in titer of local nasal antibody. Three weeks after vaccination with the 200-pg dose (P =.029), fewer vaccinees than controls yielded group C organisms on culture. Comparison of vaccinees with natural carriers of meningococci showed that the antibody response to natural nasopharyngeal infection was approximately three times greater than that conferred by the 200-pg dose of vaccine. Although not recommended to replace the parenteral vaccine, intranasal vaccination offers a safe method for study of the pathogenesis of meningococcal infection and is the best model available to study the role of local antibody in immunity.