Invasive meningococcal infections (IMI) are notifiable diseases caused by Neisseria meningitidis. They present in various clinical forms, the most common being meningitis and meningococcemia. The impact of the disease is significant due to its sudden onset, its high case-fatality rate (approximately 10% of cases), and the risk of long-term complications (amputations, deafness, etc.). Twelve serogroups of Neisseria meningitidis have been identified, six of which cause invasive infections (A, B, C, Y, X, W). IIM primarily affects young people, and in France, the majority of cases occur sporadically. Cases occur year-round, although their number is higher during the winter months. Since 2002, the annual number of reported cases has ranged between 500 and 800 cases per year.