Starting in 2003, the Seine-Maritime department experienced a hyperendemic situation involving invasive meningococcal infections (IMI) of serogroup B, specifically linked to a strain of the B:14:P1.7,16 phenotype. An area particularly affected by the hyperendemic situation, encompassing Dieppe and 74 surrounding municipalities, was identified through epidemiological analysis. In 2008, cases of IIM B:14:P1.7,16 were also observed east of the Dieppe area and in the Somme, in an area west of Abbeville bordering Seine-Maritime. The incidence of IIM B subtype P1.7,16 increased particularly in the Somme during the last quarter of 2008, indicating the emergence of a new hyperendemic focus.Vaccination campaigns against strain B:14:P1.7,16 began in 2006 in Seine-Maritime and in 2009 in the Somme to eradicate these foci. The campaign in the Dieppe area succeeded in curbing the hyperendemic outbreak, but in 2011 a focus persisted in areas east of Dieppe and in the Somme.