Apparently, meningococcal group B polysaccharide is chemically very similar/identical to some sialic acid polymers in mammalian heart valves, CNS tissues and kidney. This resemblance to host antigen may help explain why B polysaccharide is poorly immunogenic compared with serogroups A, C, Y, and W-135 polysaccharides.

[Ed. note: Group B disease continues to be problematic in the U.S.; @ 30% of meningococcal disease in college students is serogroup B. Group B vaccines based on the outer membrane vesicle of the organism, which contains minimal to no group B polysaccharide, are in research trials. Unfortunately, antibody titers wane quickly and are not as efficacious as once was thought. Protein conjugation of Group B polysaccharide (similar to that already used with Hib and S. pneumoniae) may be an issue because of concern about cross-reacting antibodies to polysialic acid and epitopes on vital human organs.]