Immunogenicity and safety of MenACWY-TT, a quadrivalent meningococcal tetanus toxoid conjugate vaccine recently licensed in the United States for individuals ≥2 years of age

Vaccination offers the best way to prevent invasive meningococcal disease (IMD). As demonstrated in countries with national immunization programs (NIPs) against IMD, meningococcal conjugate vaccines have contributed to significant declines in incidence. Since some meningococcal vaccines are associated with modest immunogenicity in infants, possible immunological interference upon concomitant administration with some pediatric vaccines, and administration errors resulting from improper reconstitution, opportunities for improvement exist. A quadrivalent conjugate vaccine, MenQuadfi® (Meningococcal [Serogroups A, C, Y, and W] Conjugate Vaccine; Sanofi, Swiftwater, Pennsylvania), was approved in 2020 for the prevention of IMD caused by meningococcal serogroups A, C, W, and Y in individuals ≥2 years of age in the United States. Five pivotal studies and one ancillary study supported approval in the United States; clinical trials in infants are ongoing. Data on the immunogenicity and safety of this vaccine are presented, and its potential value in clinical practice is discussed.

A novel vaccine to prevent meningococcal disease beyond the first year of life: an early review of MenACYW-TT

INTRODUCTION

Although quadrivalent meningococcal conjugate vaccines have been effective in preventing invasive meningococcal disease (IMD) caused by serogroups A, C, W, and Y across age groups from infants to adults, data on their efficacy and safety in adults ≥56 years of age are lacking. Moreover, multiple available quadrivalent conjugate vaccines require reconstitution prior to administration, introducing the potential for error. A novel quadrivalent meningococcal conjugate vaccine, MenACYW-TT (MenQuadfi®) was approved in 2020 for use in individuals ≥12 months of age as a single dose in the European Union and some other countries and in individuals ≥2 years of age in the United States.

AREAS COVERED

The findings of Phase II/III studies that included >6600 individuals and evaluated the immunogenicity and safety of MenACYW-TT beyond the first year of life are comprehensively summarized and discussed.

EXPERT OPINION

Extensive data on immunogenicity and safety, co-administration with routine vaccines, elicitation of robust booster responses, and significantly higher Men C responses versus monovalent MenC or MenACWY standard-of-care vaccines in toddlers suggest that MenACYW-TT may be suitable for inclusion in National Immunization Programs (NIPs) globally. The authors provide their perspectives on the clinical use of MenACYW-TT across age groups from toddlers through adults.

Antibody kinetics following vaccination with MenAfriVac: an analysis of serological data from randomised trials

BACKGROUND

A meningococcal group A conjugate vaccine, PsA-TT (also known as MenAfriVac), was developed with the support of the Meningitis Vaccine Project. Around 280 million individuals aged 1-29 years have been immunised across the African meningitis belt. We analysed the kinetics of vaccine-induced antibody response and assessed the possible implications for duration of protection.

METHODS

We obtained data from two longitudinal studies done in The Gambia, Mali, and Senegal of antibody responses in 193 children aged 12-23 months and 604 participants aged 2-29 years following MenAfriVac vaccination. Antibodies were measured using two methods: group A serum bactericidal antibody (SBA) assay and group A-specific IgG ELISA. Data on antibody responses were analysed using a mixed-effects statistical model accounting for the mean response and variation in patterns of antibody kinetics. Determinants of antibody duration were investigated using regression analysis.

FINDINGS

In children age 12-23 months, the reduction in MenAfriVac-induced antibody levels assessed by SBA titres had two phases: with 97·0% (95% credible interval [CrI] 95·1-98·3) of the response being short lived and decaying within the first 6 months and the remainder being long lived and decaying with a half-life of 2690 days (95% CrI 1016-15 078). Antibody levels assessed by SBA titres in participants aged 2-29 years were more persistent, with 95·0% (85·7-98·1) of the response being short lived, and the long lived phase decaying with a half-life of 6007 days (95% CrI 2826-14 279). Greater pre-vaccination antibody levels were associated with greater immunogenicity following vaccination, as well as greater antibody persistence. Despite rapid antibody declines in the first phase, antibodies in the second phase persisted at SBA titres greater than 128. Although there is no strong evidence base for a correlate of protection against infection with Neisseria meningitidis serogroup A, we use an assumed SBA titre of 128 as a threshold of protection to predict that 20 years after vaccination with a single dose of MenAfriVac, vaccine efficacy will be 52% (29-73) in children vaccinated at age 12-23 months and 70% (60-79) in participants vaccinated at age 2-29 years.

INTERPRETATION

Population-level immunity induced by routine vaccination with the Expanded Programme on Immunization is predicted to persist at levels sufficient to confer more than 50% protection over a 20-year time period. Further increases in population-level immunity could be obtained via mass campaigns or by delaying the age of vaccination through the Expanded Programme on Immunization. However, the benefits of such a strategy would need to be weighed against the risks of leaving young children unvaccinated for longer.

FUNDING

Meningitis Vaccine Project and Institut Pasteur.