[The post-licensing efficacy of VA-MENGOC-BC in children under 6 in Holguín, Cuba. The first year of observation].

The assessment of the after-licensing efficacy of the Cuban vaccine VA-MENGOC-BC was performed one year after the mass immunization campaign was completed in children under 6 years of age in the Province of Holguín which had the second highest incidence rate of meningococcal disease during 1988 in Cuba. In the design of the study the following aspects were taking into account: case definition; case detection, determination of the state of vaccination, and comparability of exposure. The utilization of 2 case definitions with different sensitivity and specificity is introduced within the methodology, as well as 2 estimation methods. Incidence rates from exposed and nonexposed subjects, as well as the ratio of cases and of the vaccinated population are used. The impact of this prophylactic intervention was determined by the estimation of the percentual preventive population fraction. Among outstanding results, the high efficacy of more than 98% found in both variants of case definition is to be mentioned. It is evidenced that the effect of the vaccine accounts for more than 80% of the observed case reduction. Such reduction in the number of cases was obtained without changing diagnostic criteria since the isolation of the agents was hept at levels similar to the ones from previous years.