In 2010, in the Manche department, 16 cases of invasive meningococcal disease (IMD) were reported to the Regional Health Agency across all serogroups, out of a population of 496,000. Of the 16 cases observed, 11 were serogroup B. In 2010, Manche ranked third among French departments in terms of the incidence of both IIM across all serogroups and IIM of serogroup B alone. The question of a potential epidemic or hyperendemic situation arose, and a more in-depth analysis of the situation was conducted by Cire Normandie. Thus, in 2010, 2.2 times more cases of IIM were observed compared to the expected number of cases calculated over the last three calendar years, whether for all serogroups combined or for serogroup B alone. This increase is statistically significant. IIM B cases involved several types of meningococcal strains. None of the temporal-spatial clusters investigated resulted in the epidemic threshold being exceeded. However, the high proportion of cases definitively or likely involving the B:14:P1.7,16 strain (responsible for hyperendemic outbreaks in Seine-Maritime and the Somme) indicates the introduction of this clone into the Manche department. Enhanced surveillance of invasive strains is therefore continuing in 2011. In response to this situation, the High Council for Public Health has recommended vaccination with the MenBvac® vaccine for close contacts of cases potentially linked to the B14:P1.7,16 phenotype. (R.A.)