Capsule switching and capsule replacement in vaccine- preventable bacterial diseases

1have provided data to suggest that there is no compelling evidence that mass immunisation with meningococcal serogroup C conjugate vaccines will lead to capsule replacement. However, it is important to clarify two phenomena that can happen to Neisseria meningitidis when the bacteria are subjected to immune selection with vaccines that induce antibodies to only certain serogroups. These two phenomena, capsule switching and capsule replacement, are elegantly described for Streptococcus pneumoniae (another vaccine-preventable bacterial disease con trolled by vaccines that target only certain capsular types) in two recent editorial comments in the New England Journal of Medicine and Clinical Infectious Diseases. 2,3 Capsule

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