Surveillance of the epidemiology of invasive meningococcal diseases in France relies mainly on mandatory notification of cases. Up to 2001, only culture or soluble antigen confirmed cases were included in the definition of cases to be notified, and a new case definition, which includes clinically confirmed cases, will only be implemented during 2002. In 1995, the incidence reached a record low level since 1945 (0.6/100 000 inhabitants), and has since increased steadily up to 0.8/100 000 inhabitants in 2000 (1). In that same year, the average incidence of culture confirmed cases in the 15 European Union countries was 1.3 (2). Between 1995 and 2000, the proportion of C serogroup in France remained fairly constant, varying from 17% to 22% (3). The completeness of mandatory notification was estimated in 1999 at 67% through capture-recapture analysis based on data from the National Reference Centre and from a network of hospital laboratories.

In the department of Puy-de-Dôme, located in central France with a population of around 600 000 inhabitants,17 cases of meningococcal disease (MD) were notified to health authorities between March 2001 and the first week of 2002 (figure 1). Among the 15 confirmed cases, 11 were serogroup C (73%), two serogroup B (13%) and two serogroups could not be identified. Monthly distribution of cases is shown in figure 2. The incidence rate for MD serogroup C (CMD), in an analysis restricted to 2001, was 1.7 cases/100 000 inhabitants compared with 0.3/100 000 at national level; the proportion of CMD was 71% (10/14) compared with 35% at national level (p < 0,01). From 1 January 2001 to 10 January 2002, 64% (7/11) of the cases presented with purpura fulminans (PF) and 27% (3/11) died. In the same period in the rest of France, purpura fulminans was recorded for 27% of cases (p =0.03), and the case-fatality ratio was 15% (p = 0.55). Seven cases occurred in the departmental capital, Clermont-Ferrand (incidence rate:

5.1/ 100 000). Among the 11 CMD cases, six cases and two deaths occurred between Novem- ber 2001 and the first week of January 2002. The distribution of the patients by age group did not differ from the one observed at national level (p=0.45), with six out of 11 cases (55%) in children below five years of age. One case was in a patient over 20 years of age (24 years) who was, however, studying in a professional school that was located within a secondary school. The epidemiological situation in the rest of the department, and in the neighbouring departments, was comparable to the situation in the country as a whole. Two different groups of type C Neisseria meningitidis were identified by the National Reference Centre through multi-loci DNA fingerprinting performed on nine strains. One of the groups (5 strains) belonged to the ET-37 clonal complex, known to include epidemic strains, and was responsible for the deaths of the 3 CMD cases. Similarity of the 2 groups is still under investigation through further genotyping. In conclusion, when compared with other departments, the situation of the Puy-de-Dôme department appeared unique, in regard to both incidence rate for CMD, and severity of the cases. The rapid increase in the number of cases during a period of low endemicity for the rest of the country, and before the annual seasonal peaks for both influenza and meningococcal diseases, was a further subject of concern.

This analysis led the National Institute for Public Health Surveillance (InVS) to recommend a local vaccination campaign targeting children from 2 months up to 20 years living or studying in a limited area of he department, defined as the geographical area including all the CMD cases reported since March 2001. The inclusion of infants in the target population was made possible by the simultaneous licensing of one of the newly developed meningococcal C conjugate vaccine (Meningitec®). This proposal was approved by the French Technical Committee on Immunisation on 11 January 2002, and endorsed by the Minister of Health on the same day. Vaccination was also recommended for 20-24 year olds in the same area, if living in student dormitories or closed communities, or working with children. Children entering the department under certain circumstances were also targeted (collective stay or stay of at least one month). Considerations of effectiveness, likely impact on carriage of the bacteria and simplification of logistics and messages led to the use of the conjugate meningococcal vaccine, rather than the polysaccharide one, for the whole target population, estimated at close to 100 000 people. Vaccination activities began on 16 January. Vaccination was offered free of charge to the target population through school, child health or vaccination clinics and private practices. School-based vaccination ended on 9 February, when the schools closed for holidays, and the campaign ended on 9 March. An estimated 80 000 children or adolescents were immunised, including 63 000 through the public sector. Active pharmacovigilance procedures set up for the campaign have not identified any severe adverse effects. Of the 1390 immediate adverse effects notified from the public sector, more than half were headache and dizziness. As of mid-March, no further case of MD has been notified from the department since 6 January.