[Evaluation of the effectiveness of targeted vaccination with the meningococcal polysaccharide A and C vaccine in one location in the Czech Republic].

In the Czech Republic where meningococcal disease occurred only sporadically for a very long period and Neisseria meningitidis B prevailed, the use of a meningococcal polysaccharide vaccine was never indicated. This situation changed in 1993 when a new clone of Neisseria meningitidis C:2a:P1.2(P1.5) appeared in the Czech Republic, found to be responsible for a new epidemiological and clinical situation. The disease caused by this new clone is more serious, showing a high fatality rate (20%) and frequently an atypical clinical course. In May 1993, the highest age-specific incidence in the most affected locality was established in the age group of 15-19 years (52.1/100,000), while in the whole Czech Republic the respective figure was 2.4. A vaccination campaign focusing on the most affected age group started in this locality at the beginning of June 1993, using a polysaccharide meningococcal vaccine A+C (Mérieux). During two weeks 6191 students of the age group of 15-19 years were vaccinated, i.e. 96% of all students of this age group, 64.5% of the population 15-19 years old and 5.6% of the whole population of this locality. This age targeted vaccination prevented the spread of the meningococcal invasive disease caused by Neisseria meningitidis C in this locality. The decrease in morbidity in this locality is statistically highly significant (p < 0.001). In another affected locality, where vaccination was not age targeted and showed a very low coverage, the incidence of the invasive disease caused by Neisseria meningitidis C did not decrease. During the following period (1993-1994) the new meningococcal clone spread to all regions of the Czech Republic. Active surveillance of meningococcal invasive disease has been conducted with the aim to recognize as early as possible an emerging epidemiological indication for targeted vaccination.