Serum IgG reactivity to 3 recombinant antigens in Neisseria meningitidis serogroup B meningococcal vaccine (MenB-4C) (Bexsero; GlaxoSmithKline, Bellaria Rosia, Sovicille, Italy), determined by ELISA. A postmortem serum sample (3) from a 16-year-old girl with paroxysmal nocturnal hemoglobinuria who died of meningococcal disease after treatment with eculizumab. Reactivity was measured in parallel with stored serum from 10 unvaccinated college students (1) and 10 vaccinated college students (2) 7 months after vaccination with MenB-4C (8). For the comparison specimens, each data point represents reactivity of an individual person. A) Factor H binding protein. B) Neisseria heparin binding antigen. C) NadA, MenB-4C antigens absent. OD, optical density. Data points for (3) indicate results of replicate assays. OD, optical density.