Demonstration of immunologic memory using serogroup C meningococcal glycoconjugate vaccine

Use of a booster dose of capsular group C meningococcal glycoconjugate vaccine to demonstrate immunologic memory in children primed with one or two vaccine doses in infancy

BACKGROUND

Use of a polysaccharide vaccine challenge to demonstrate immunologic memory after priming with capsular group C meningococcal conjugate vaccines (MenCC) risks induction of immunologic hyporesponsiveness. For this reason, MenCC vaccines are now used as probes of immunologic memory, however, no studies have demonstrated their ability to distinguish primed from unprimed children.

METHODS

This study was part of a randomised controlled trial investigating the immunogenicity of a booster dose of the combined Haemophilus influenzae type b and MenC-tetanus toxoid vaccine (Hib-MenC-TT) in infants receiving reduced dose MenCC vaccine priming schedules (one MenC-CRM/MenC-TT or two MenC-CRM vaccine doses) compared with an unprimed group. Antibody kinetics were studied in a subset of 269 children by measuring changes in the MenC serum bactericidal antibody, using rabbit complement, (MenC rSBA) titres and MenC specific IgG memory B-cells before and at 6 and 28days following the 12month booster vaccination.

RESULTS

At 6days after the 12monthMenCC vaccine, the rise in MenC rSBA titres and MenC specific IgG memory B-cells of the primed groups were significantly higher than the infant MenCC naïve group. Participants primed with one MenC-TT dose had the highest increase in MenC rSBA titres compared with all other groups. The MenC rSBA titres at the 28th compared with the 6th day after boosting was significantly higher in those primed with a single MenC-TT/MenC-CRM vaccine in infancy compared with those who were not primed or who were primed with two doses of the MenC-CRM vaccine.

CONCLUSION

Immunologic memory can be demonstrated by a MenCC booster vaccination but is affected by the type and number of MenCC doses used for infant priming. The MenC rSBA responses can be used to demonstrate successful immunologic priming.

Serogroup C Neisseria meningitidis invasive infection: analysis of the possible vaccination strategies for a mass campaign

The serogroup C meningococcal conjugate vaccine is available since 1999. In the absence of randomized controlled trials that support a specific schedule, each country has adopted different vaccination programmes. Hereby, we analyse positive and negative aspects of the different vaccination strategies.

CONCLUSION

While waiting for the introduction of other antimeningococcal vaccines, covering also for the Group B meningococci, further studies on effectiveness of an optimal schedule to be adopted in European countries are needed.

Safety and immunogenicity of an investigational quadrivalent meningococcal conjugate vaccine after one or two doses given to infants and toddlers

With the emergence of multiple meningococcal serogroups in different geographic areas, broad vaccine protection from infancy is desirable. One hundred and seventy-five infants received either two doses of a meningococcal quadrivalent (A, C, W-135, Y) conjugate vaccine (MenACWY-CRM) at 6 and 12 months, one dose of MenACWY-CRM at 12 months, or MenC at 12 months and MenACWY-CRM at 18 months. Bactericidal antibody titers using human complement were measured before and 1 month after each dose. Injection-site reactions were reported by 22-45% of participants following MenACWY-CRM given at 6 or 12 months. Similar proportions of subjects had injection-site reactions following two doses of MenACWY-CRM (32-41%) or one dose of MenC (26-44%). The incidence of systemic adverse events was comparable between groups. After two doses of MenACWY-CRM, the percentages of participants reporting hSBA titers >or=8 were 100% for C, W-135, and Y, and 84% for A. Serogroup C titers were more than 10-fold higher after two doses of MenACWY-CRM than after one dose of MenC or MenACWY-CRM at 12 months. Serogroup C titers were comparable following a single dose of MenACWY-CRM or MenC at 12 months. MenACWY-CRM is well tolerated and immunogenic given at 12 months, or two doses at 6 and 12 months of age.