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Meningococcal Serogroup ACWYX Conjugate Vaccine in Malian Toddlers
Milagritos D Tapia1, Samba O Sow1, Abdi Naficy1
1From Centre pour le Développement des Vaccins du Mali, Bamako (M.D.T., S.O.S., F.D., F.C.H., A.T.); the Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore (M.D.T.); PATH, Seattle (A.N., L.M., N.H., I.S., Y.T., M.R.A.); the Serum Institute of India, Pune (A.C., S.S.P., F.M.L., R.M.D., D.K., P.S.K.); and the Vaccine Evaluation Unit, Public Health England, Manchester Royal Infirmary, Manchester, United Kingdom (K.T.-P., R.B.).
Insights
A new pentavalent meningococcal vaccine (NmCV-5) shows promising safety and immunogenicity in children. Both adjuvanted and nonadjuvanted NmCV-5 demonstrated comparable immune responses, suggesting potential for broader meningococcal disease prevention.
Area of Science:
- Immunology
- Vaccinology
- Infectious Diseases
Background:
- Neisseria meningitidis serogroups A, B, C, W, X, and Y are key causes of meningococcal disease outbreaks.
- Quadrivalent vaccines against serogroups A, C, W, and Y are currently available.
- A pentavalent vaccine, NmCV-5, targeting these serogroups plus X, is under development.
Purpose of the Study:
- To evaluate the safety and immunogenicity of a novel pentavalent meningococcal conjugate vaccine (NmCV-5) in Malian children.
- To compare the efficacy of nonadjuvanted NmCV-5, adjuvanted NmCV-5, and a licensed quadrivalent vaccine (MenACWY-D).
Main Methods:
- Phase 2, randomized, observer-blinded, controlled trial in 376 children aged 12-16 months.
- Participants received two intramuscular doses of nonadjuvanted NmCV-5, adjuvanted NmCV-5, or MenACWY-D, 12 weeks apart.
- Safety was monitored for 169 days; immunogenicity assessed via serum bactericidal antibody (SBA) assays.
Main Results:
- Both NmCV-5 formulations were safe, with low rates of local and systemic adverse events, comparable to MenACWY-D.
- High SBA titers (≥128) against all five serogroups were achieved in 91-100% of NmCV-5 recipients by day 84.
- Immune responses to nonadjuvanted and adjuvanted NmCV-5 were similar; both showed robust responses by day 112.
Conclusions:
- Two doses of NmCV-5 demonstrated a favorable safety profile in children.
- A single dose of NmCV-5 elicited immune responses comparable to two doses of MenACWY-D.
- Adjuvanted NmCV-5 offered no significant advantage over the nonadjuvanted formulation.
Background:
Neisseria meningitidis serogroups A, B, C, W, X, and Y cause outbreaks of meningococcal disease. Quadrivalent conjugate vaccines targeting the A, C, W, and Y serogroups are available. A pentavalent vaccine that also includes serogroup X (NmCV-5) is under development.
Methods:
We conducted a phase 2, observer-blinded, randomized, controlled trial involving Malian children 12 to 16 months of age. Participants were assigned in a 2:2:1 ratio to receive nonadjuvanted NmCV-5, alum-adjuvanted NmCV-5, or the quadrivalent vaccine MenACWY-D, administered intramuscularly in two doses 12 weeks apart. Participants were followed for safety for 169 days. Immunogenicity was assessed with an assay for serum bactericidal antibody (SBA) with rabbit complement on days 0, 28, 84, and 112.
Results:
A total of 376 participants underwent randomization, with 150 assigned to each NmCV-5 group and 76 to the MenACWY-D group; 362 participants received both doses of vaccine. A total of 1% of the participants in the nonadjuvanted NmCV-5 group, 1% of those in the adjuvanted NmCV-5 group, and 4% of those in the MenACWY-D group reported local solicited adverse events; 6%, 5%, and 7% of the participants, respectively, reported systemic solicited adverse events. An SBA titer of at least 128 was seen in 91 to 100% (for all five serotypes) of the participants in the NmCV-5 groups and in 36 to 99% (excluding serogroup X) of those in the MenACWY-D group at day 84 (before the second dose); the same threshold was met in 99 to 100% (for all five serotypes) of the participants in the NmCV-5 groups and in 92 to 100% (excluding serogroup X) of those in the MenACWY-D group at day 112. Immune responses to the nonadjuvanted and adjuvanted NmCV-5 formulations were similar.
Conclusions:
No safety concerns were identified with two doses of NmCV-5. A single dose of NmCV-5 elicited immune responses that were similar to those observed with two doses of MenACWY-D. Adjuvanted NmCV-5 provided no discernible benefit over nonadjuvanted NmCV-5. (Funded by the U.K. Foreign, Commonwealth, and Development Office; ClinicalTrials.gov number, NCT03295318.).
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