Discussion
MenACYW-TT, myalgia
This phase IIIb, open-label, partially randomized, parallel-group, multicenter trial demonstrated that a booster dose of MenACYW-TT in adolescents and adults who had been vaccinated 3–6 years earlier with a single dose of MenACYW-TT or MCV4-CRM was immunogenic and well tolerated, with in the sufficiency of seroresponse demonstrated at Day 30 post booster. We observed a robust response to a booster dose of MenACYW-TT, with over 93% seroresponse for all serogroups in adolescents and adults. The seroresponse rate was greater than 75% for all serogroups in both Groups 1 and 2 by Day 6, suggesting a quick onset of the immune response, regardless of the priming vaccine (MenACYW-TT or MCV4-CRM). This observation supports previous studies of a booster dose of MenACYW-TT which have shown similar results,When examining the persistence of the immune response, 3–6 years after the priming vaccination with either MenACYW-TT or MCV4-CRM, prior to the booster vaccination, seroprotection ranged from 52% to 91% across the serogroups and vaccine groups. GMTs at Day 0, pre-booster, were higher than those prior to the priming vaccine in participants from previous studies,Based on the GMTRs at Day 30 post booster dose for Groups 1 (MenACYW-TT primed) and 2 (MCV4-CRM-primed), possible evidence of a statistically significant difference for serogroups C and Y (considering 95% CIs do not cross 1) was observed; however, it must be noted that a formal statistical hypothesis to evaluate such a difference was not a part of the planned analysis and is a post-hoc observation. The co-administration of the MenACYW-TT booster with a MenB vaccine did not affect the immunogenicity of serogroups A, C, Y and W, compared to the administration of the MenACYW-TT booster alone.Solicited AEs were mostly of mild intensity but showed a numerical increase, particularly in malaise and myalgia, likely influenced by the known reactogenic profile of MenB vaccines.While this study assessed the co-administration of MenACYW-TT and MenB vaccines, the immunogenicity of MenB vaccines when co-administered with MenACYW-TT was not assessed in this study due to non-availability of relevant assays. It will be important to address this in future studies. In addition, we did not have pre- or post-priming vaccine data for the 49 participants who had not participated in the previous MET50 or MET43 clinical studies and as such these participants were not included in the analysis of antibody persistence. This study may also have benefitted from the inclusion of an additional group of participants as a control to assess the response of a single dose of MenACYW-TT in vaccine-naïve participants; however, studies showing robust immunogenicity of a single dose of MenACYW-TT in this age group have been published previously.This study offers key data about the immunogenicity and safety of MenACYW-TT when administered as a booster alone or co-administered with a MenB vaccine, in participants primed with MenACYW-TT or MCV4-CRM. A booster dose of MenACYW-TT produced a comparable and robust response to all serogroups in adolescents and adults who had received a priming dose of either MenACYW-TT or MCV4-CRM 3–6 years earlier. In addition, no interference of the immune response to MenACYW-TT was observed when MenACYW-TT was co-administered with MenB-T or 4CMenB vaccines.