Comparison of antibody kinetics following meningococcal serogroup C conjugate vaccine between healthy adults previously vaccinated with meningococcalA/C polysaccharide vaccine and vaccine-naive controls

Few data are available on the kinetics of meningococcal serogroup C-specifi c antibody production following meningococcal serogroup C conjugate (MCC) v accination, particularly in those who have received prior meningococcal A/C polysaccharide (MACP) vaccination(s). Laboratory staff who had previously received either one dose (n = 35), two doses (n = 18) of MACP vaccine or wh o were naive to previous meningococcal vaccination (n = 42) were vaccinated with R ICC. Bloods were taken pre-vaccination. on the subsequent 4 days an d on days 10 and 28. Serogroup C serum bactericidal antibody (SBA), and ant i-serogroup C-specific IgG, IgM and IgA were measured. There were no signif icant differences between the groups who had received either 2 or 1 prior d ose(s) of MACP, therefore, these results were combined. Up to day 4 there w as no evidence of a significant increase or decrease in the median levels o f SEA, IgG, IgM or IEA in either the naive: or MACP groups, although about 20% of individuals did have 4-fold SEA rises by day 4. By day 10 there were large significant increases in the levels of SEA, IgG, IgM and IgA with re spective fold increases from pre-vaccination levels of 4.6, 1.9, 1.2 and 2. 1 in the MACP group and 270. 13.4, 4.8 and 33.8 in the naive group. Further significant increases were seen between day 10 and 28 for SEA, IgG and IgM (naive group only). By day 18, 4-fold SEA rises had occurred in 63.50% of the MACP group and 97.6% of the nai:ve group. The SEA GMT on day 28 signifi cantly differed between the naive and MACP groups with GMT 2.8-fold higher in the naive group (P=0.021). In conclusion, no decline in serogroup C-spec ific antibody levels was demonstrated immediately post-MCC vaccination whil st these levels had risen significantly by day 10. Putative protective SEA titres (greater than or equal to 8, 32 or 128) were observed by day 10 foll owing MCC vaccination regardless of MACP history. (C) 2001 Elsevier Science Ltd. All rights reserved.