title: Immune response to meningococcal serogroup C conjugate vaccine in asplenic individuals.
abstract: Asplenic individuals are known to be at increased risk of infection with encapsulated bacteria. Recent United Kingdom recommendations stated that this at-risk group should receive one dose of the meningococcal serogroup C conjugate (MCC) vaccine. However, the immune response of asplenic individuals to MCC vaccine is unknown. The immune response of asplenics (n = 130) to immunization with the MCC vaccine was investigated. Asplenic individuals had a significantly lower geometric mean titer (GMT) (157.8; 95% confidence interval [CI], 94.5 to 263.3) of bactericidal antibody in serum (SBA) than an age-matched control group (n = 48) (1448.2; 95% CI, 751.1 to 2792.0). However, 80% of asplenic individuals achieved the proposed protective SBA titer of > or =8. No differences were observed between the two groups in the serogroup C-specific immunoglobulin G geometric mean concentration. A significant reduction in SBA GMT or the number of responders achieving an SBA titer of > or =8 was observed if the reason for splenectomy was a medical cause or if MCC vaccination occurred <10 years after splenectomy. Individuals (n = 29) who did not achieve an SBA titer of > or =16 were offered a second dose of MCC vaccine. Analysis of the SBA response revealed that 61% (14 of 23) of the individuals who received a second dose achieved a protective titer. In total, 93% of asplenic individuals achieved a titer of > or =8 following MCC vaccination (one or two doses combined). We recommend that, following vaccination of asplenics, either the level of functional antibody should be determined, with a second dose of MCC vaccine offered to nonresponders, or two doses of MCC vaccine should be routinely offered.
authors.affiliation: Manchester Laboratory, Health Protection Agency North West, Manchester Medical Microbiology Partnership, Manchester M13 9WZ, United Kingdom. paul.balmer@hpa.org.uk
authors.forename: Paul
authors.initials: P
authors.lastname: Balmer
authors.forename: Michelle
authors.initials: M
authors.lastname: Falconer
authors.forename: Paula
authors.initials: P
authors.lastname: McDonald
authors.forename: Nick
authors.initials: N
authors.lastname: Andrews
authors.forename: Emily
authors.initials: E
authors.lastname: Fuller
authors.forename: Christine
authors.initials: C
authors.lastname: Riley
authors.forename: Edward
authors.initials: E
authors.lastname: Kaczmarski
authors.forename: Raymond
authors.initials: R
authors.lastname: Borrow
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000907:Antibodies, Bacterial / Q000097:blood*; D001770:Blood Bactericidal Activity; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008589:Meningococcal Infections / Q000276:immunology* / Q000517:prevention & control; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D008875:Middle Aged; D009345:Neisseria meningitidis / Q000276:immunology*; D013156:Splenectomy
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D022401:Meningococcal Vaccines; C410218:serogroup C meningococcal conjugate vaccine