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. 2025 May;14(5):991-1010.
doi: 10.1007/s40121-025-01121-6. Epub 2025 Apr 1.

Five-Year Immune Persistence of a Quadrivalent Meningococcal Conjugate Vaccine (MenACYW-TT) and Immunogenicity and Safety of a Booster Dose in Children

Federico Martinón-Torres  1   2   3 , Robert Simko  4 , Rolf Ebert  5 , Mika Rämet  6 , Céline Zocchetti  7 , Olga Syrkina  8 , Siham Bchir  9 , Isabelle Bertrand-Gerentes  10
Affiliations

Five-Year Immune Persistence of a Quadrivalent Meningococcal Conjugate Vaccine (MenACYW-TT) and Immunogenicity and Safety of a Booster Dose in Children

Federico Martinón-Torres et al. Infect Dis Ther. 2025 May.

Abstract

Introduction: Many countries recommend vaccination against Neisseria meningitidis serogroups A, C, W, and Y in infants and young children to prevent invasive meningococcal disease. We evaluated the immunogenicity and safety of a quadrivalent meningococcal tetanus toxoid-conjugate vaccine (MenACYW-TT) booster in children primed with the same meningococcal vaccine 5 years earlier. Immune persistence following priming vaccination was also evaluated, and the study is ongoing to generate 10 years' post-priming data.

Methods: Healthy children, vaccinated with MenACYW-TT 5 years earlier as toddlers, were enrolled. Participants were randomized to receive MenACYW-TT booster (group 1) or no booster (group 2), stratified by country and meningococcal serogroup C (MenC) vaccination status (primed at age ≤ 1 year vs. naive). Antibodies against each serogroup were measured by serum bactericidal assay using human complement (hSBA). Seroresponse sufficiency at 30 days post-booster was demonstrated if the lower limit of the one-sided 97.5% confidence interval (CI) of the seroresponse rate (proportion of participants with post-vaccination titers ≥ 1:16 when baseline titers were < 1:8 or with a ≥ fourfold increase when baseline titers were ≥ 1:8) was > 75% for each serogroup. Seroprotection rates (proportion with hSBA titers ≥ 1:8) and geometric mean titers (GMTs) for each serogroup were also assessed.

Results: A total of 209 participants were enrolled across 26 sites in Finland, Germany, Hungary, and Spain (group 1, n = 93; group 2, n = 116). Five years post-priming, GMTs, and seroprotection rates were higher than those observed before priming vaccination in both groups, indicating long-term persistence. Booster seroresponse rates in group 1 for all serogroups ranged from 93.2% to 98.9%, with seroresponse sufficiency demonstrated (lower limit of one-sided 97.5% CIs for the seroresponse rates ranging from 85.7% to 93.8%). Seroprotection rates and GMTs post-booster increased across all serogroups, with nearly all participants seroprotected, suggesting adequate booster response. Seroresponse was comparable between MenC-primed and MenC-naive participants. No new safety concerns were identified.

Conclusions: MenACYW-TT provides long-term immune persistence and a robust immune response when administered as a booster in children primed 5 years earlier.

Trial registrations: Clinicaltrials.gov, NCT04936685; EudraCT: 2021-000104-38; WHO: U1111-1255-4941. Graphical abstract available for this article.

Keywords: Booster dose; Children; Immune persistence; Invasive meningococcal disease; MenACYW-TT; Toddlers; Vaccine.

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Conflict of interest statement

Declarations. Conflict of Interest: Céline Zocchetti, Olga Syrkina, Siham Bchir and Isabelle Bertrand-Gerentes are employees of Sanofi and may hold shares and/or stock options in the company. Mika Rämet: Finnish Vaccine Research Ltd. (formerly Tampere University Vaccine Research Center) carries out clinical vaccine trials sponsored by all major vaccine manufacturers including Sanofi. Rolf Ebert has no conflicts of interest to disclose. Robert Simko: Scientific lecture fees from Sanofi. Federico Martinón-Torres: Acted as principal investigator in randomized controlled trials of Ablynx, Abbot, Seqirus, Sanofi Pasteur MSD, Sanofi Pasteur, Cubist, Wyeth, Merck, Pfizer, Roche, Regeneron, Jansen, Medimmune, Moderna, Novavax, Novartis, and GSK, with honoraria paid to his institution. FM-T also reports consulting or advisory relationships with GSK Vaccines SRL, Pfizer Inc, Sanofi Pasteur Inc, Janssen Pharmaceuticals Inc, Moderna, MSD, and Seqirus Pty Ltd. Ethical Approval: This study was conducted in accordance with the protocol and consensus ethical principles derived from international guidelines, including the Declaration of Helsinki, the International Council for Harmonisation guidelines for Good Clinical Practice, and all applicable laws, rules, and regulations. The study protocol, informed consent form, and investigator’s brochure were reviewed and approved by the Independent Ethics Committee (IEC) and/or Investigational Review Board (IRB) for each study site before the study was initiated. The IECs/IRBs for all study centers are listed in the supplementary materials (Supplementary Table 1). Parents or other legally acceptable representatives of participants were required to sign a statement of informed consent.

Figures

Fig. 1
Fig. 1
Study design. D day, N/A not applicable, SAE serious adverse event, TC telephone call, Y year. *The TC at D9 and D31 are applicable only to group 1. †TC is applicable to both groups. MET51 study, NCT02955797
Fig. 2
Fig. 2
Participant disposition flow chart. D day, MenACYW-TT quadrivalent meningococcal tetanus toxoid-conjugate vaccine, N number of participants
Fig. 3
Fig. 3
Persistence of hSBA antibody response for meningococcal serogroups A, C, W, and Y – GMTs (FAS). D day, FAS full analysis set, GMT geometric mean titer, hSBA serum bactericidal assay using human complement. MEQ00073 study, NCT04936685; MET51 study, NCT02955797
Fig. 4
Fig. 4
Persistence of hSBA antibody response for meningococcal serogroups A, C, W, and Y – percentage of participants with hSBA titers ≥ 1.8 (FAS). D day, FAS full analysis set, GMT geometric mean titer, hSBA serum bactericidal assay using human complement. MEQ00073 study, NCT04936685; MET51 study, NCT02955797
See this image and copyright information in PMC

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