Abstract

In November 2023, a cluster of two invasive meningococcal disease (IMD) cases caused by serogroup B Neisseria meningitidis (MenB) occurred in elderly residents (≥ 70 years) of a dementia care home in England. An epidemiological investigation was conducted and public health actions, including infection control measures and antibiotic chemoprophylaxis, were implemented to prevent further cases. Nasopharyngeal swabbing before chemoprophylaxis identified three meningococcal carriers, including two carrying the outbreak strain, highlighting the importance of immediate antibiotic prophylaxis in such settings. Microbiological investigations showed that the outbreak strain belonged to the sequence type (ST)-9316 complex, potentially covered by the 4CMenB vaccine. Although 4CMenB is licensed for children and adults, there are no safety or reactogenicity data on use in older adults (≥ 65 years). Given the severity of IMD, residents (64–95 years) and staff (18–72 years) were offered 4CMenB for longer-term protection, with daily diary cards to monitor side effects. In total, 30 residents and 35 of 47 staff received the first dose, with completed diary cards for 26 residents and 32 staff. Twenty-six residents and 28 staff received the second dose, and all completed diary cards. Elderly residents reported fewer and less severe side effects after each dose than younger staff.