2ND CONTROLLED FIELD TRIAL OF A SEROGROUP-A MENINGOCOCCAL POLYSACCHARIDE VACCINE IN ALEXANDRIA

  • 1 January 1977
    • journal article
    • research article
    • Vol. 55  (6) , 645-651
Abstract
The encouraging results of an earlier controlled field trial of the serogroup A meningococcal polysaccharide vaccine in the prevention of clinical disease prompted this study, the aim of which was to evaluate further the effectiveness of another lot of this type of vaccine, the duration of immunity and the effectiveness against meningococcal carriage. A controlled field trial was carried out in early 1973 on 176,646 schoolchildren 6-15 yr of age, of whom half received the serogroup A polysaccharide vaccine and the other half tetanus toxoid as a control. The incidence of cerebrospinal meningitis caused by serogroup A meningococci was 89% lower in the immunized group than in the controls for 1 yr only. With regard to its effect on carriage, the vaccine reduced to less than half the rate of new acquisition of serogroup A meningococci during the period immediately following immunization. The duration of the carrier state was also shortened in the immunized group.