Meningococcal polysaccharide vaccination of military recruits in Israel: preliminary assessment of vaccine effect.

Meningococcal disease in the Israel Defense Force is caused mainly by serogroups C and Y. Immunization of recruits with quadrivalent polysaccharide vaccine was introduced in November 1994. The person-time incidence rate dropped from 1.33 cases per 100,000 person-years for the preceding decade to 0 for the 32 months following immunization (p = 0.025).