Protecting the most vulnerable age group: a review of MenACWY-TT immunogenicity and safety in infants.

INTRODUCTION

Neisseria meningitidis causes invasive meningococcal disease (IMD), with the highest incidence observed in infants and young children. Meningococcal serogroups A, B, C, W, X, and Y account for almost all IMD cases worldwide. Available meningococcal vaccines targeting serogroups A, C, W, and Y (MenACWY) include those conjugated to diphtheria toxoid (MenACWY-D), diphtheria protein cross-reactive material 197 (MenACWY-CRM197), and tetanus toxoid (MenACWY-TT). MenACWY-TT is indicated for use starting at 6 weeks of age.

AREAS COVERED: This review discusses data from the four primary studies assessing MenACWY-TT safety and immunogenicity in infants, which evaluated a variety of dosing schedules, short-term and long-term outcomes, and impact of coadministration on the immunogenicity of routine childhood vaccines. Remaining gaps in the field are addressed.

EXPERT OPINION: Robust data support the use of MenACWY-TT in infants starting as early as 6 weeks of age. MenACWY-TT was safe and well tolerated in infants, was immunogenic after priming and booster, and demonstrated persistent immunogenicity. Lower persistence for serogroup A relative to other serogroups based on serum bactericidal assays (SBAs) using human complement appears to be a class effect of MenACWY conjugate vaccines. Correlates of protection other than SBA are being explored, including immunologic responses associated with different carrier proteins.