Large outbreak of group B invasive meningococcal disease in young adults in South East England, March 2026

An unusually large outbreak of invasive meningococcal disease affecting young adults occurred in South East England between 13 and 18 March 2026, with 21 confirmed cases including two fatalities. Thirteen cases were university students and 19 had attended the same nightclub over a 3-day period. The outbreak strain was a distinct genome within the previously seen type B: P1.12–1,16–183: F1–5: ST-485 (cc41/44). Over 13,000 chemoprophylaxis doses and 11,000 meningococcal B vaccinations were provided to possible contacts.