Safety and immunogenicity of concomitant quadrivalent meningococcus ACYW-TT and meningococcus group B vaccines.

Infants are vulnerable to meningococcal disease. In this open-label phase III study (NCT03632720; registered 13/8/2018), infants were randomised to quadrivalent ACWY conjugated vaccine, MenACYW-TT, at 3 and 12-13 months and four-component meningococcus group B vaccine (4CMenB) at 2, 4, and 12-13 months (Group 1), MenACYW-TT at 3 and 12-13 months and 4CMenB at 2 and 4 months (Group 2), or 4CMenB at 2, 4, and 12-13 months (Group 3). Routine vaccines were also administered per UK schedule. Primary outcome of non-inferiority of seroprotection rates against the four capsular groups (A, C, W, and Y) in Group 1 versus Group 2 at day 30 after the second vaccine dose was demonstrated with seroprotection rates ≥99% against all capsular groups in both groups. In Group 3, cross-reactivity was observed, with hSBA titres against capsular groups A and C increasing >10-fold after the third 4CMenB dose. Reactogenicity was consistent with the known profiles of both vaccines; one case of anaphylaxis related to MenACYW-TT was reported and resolved without sequelae. No new safety concerns were identified.