OBJECTIVES: To assess the potential use of a protein-based meningococcal group B 
(MenB) vaccine (Bexsero(®)) in addition to antibiotic chemoprophylaxis for 
preventing secondary cases.
METHODS: Published studies on the risk of secondary meningococcal infections 
were used to estimate the numbers needed to vaccinate (NNV) with Bexsero(®) to 
prevent a secondary case in household and educational settings.
RESULTS: Most secondary cases occur within a few days of diagnosis in the index 
case. Unlike conjugate vaccines, early protection offered after a single dose of 
Bexsero(®) is likely to be low, particularly in young children, who are at 
higher risk of secondary infection. NNV was dependent on predicted meningococcal 
strain coverage, estimated onset of protection after one Bexsero(®) dose and 
estimated vaccine efficacy. Even in the most favourable scenario where we assume 
the vaccine is administered within 4 days of the index case and prevents 90% of 
cases occurring after 14 days, the NNV for household contacts was >1000. NNV in 
educational settings was much higher.
CONCLUSIONS: The estimated NNV should be taken into account when deciding policy 
to recommend Bexsero(®) for close contacts of single cases in household or 
educational settings. Bexsero(®) may have a protective role in clusters and 
outbreaks.